B. subtilis biofilm formation, flocculability, surface characteristics and thermodynamic properties. An optimal concentration of TCS, a metabolic uncoupler, was observed to substantially inhibit biofilm formation and the secretion of extracellular polymeric substances (EPS). The effect of TCS on the zeta potential and flocculability of bacterial suspension implied the addition of 100 μg L−1 TCS increased the net negative charge of cell surface which induced the reduction of B. subtilis flocculability. Meanwhile, the effects of TCS on bacterial surfacial thermodynamic properties were analyzed by the Derjaguin–Landau–Verwey–Overbeek (DLVO) and extend DLVO (XDLVO) theories. As DLVO and XDLVO predicted, the primary energy barrier between bacterial cells incubated with 100 μg L−1 TCS were increased compared to that of control, indicating that B. subtilis incubated with 100 μg L−1 TCS must consume more energy to aggregate or form biofilm.In order to understand the inhibitory mechanism of metabolic uncoupler in biofilm, this study investigated the effect of TCS on  This study aimed to investigate the inhibitory mechanism of metabolic uncoupler on biofilm formation through surface characteristics and thermodynamics analysis. Although some previous studies found the presence of uncoupler inhibited the production of ATP and QS signals which might be the cause of biofilm reduction,29–31,34 the potential effect of TCS on surface characteristics and thermodynamics properties would be important to understand the inhibitory mechanism of uncoupler on biofilm formation.Numerous biological methods for biofouling control and inhibiting biofilm formation have recently gained increasing attentions and introductions.35 In biofilm formation process, the initial colonist bacteria adhere to the surface through weak, reversible adhesion via van der Waals forces and hydrophobic effects.36 Hydrophobicity and hydrophilicity can directly affect the behaviour of bacteria to aggregate.37 Therefore, the aggregation and biofilm formation of bacteria are closely related to bacterial surface characteristics including the surface charge and hydrophobicity/hydrophilicity.38,39 Therefore, investigating the changes of bacterial hydrophobicity/hydrophilicity and surface charge induced by uncoupler would be beneficial for the understanding the inhibitory function of metabolic uncoupler.Most bacterial surfaces are negatively charged and contain hydrophobic surface components.37,38 Liu et al.37 applied the DLVO theory to investigate the flocculation characteristics and suspension stability of H2-producing photosynthetic bacteria, Rhodopseudomonas acidophila. Compared with the traditional DLVO theory, the XDLVO model additionally considers an acid–base (AB) (electro donor/electron acceptor) interaction between two surfaces immersed in a polar solvent.38 Surface thermodynamics and interfacial tension for many polymeric surfaces and microorganisms submerged in water have implied the AB interaction contribution.40–42 In the study of Xiao et al.,43 the XDLVO theory was explored to describe the combined effect of membrane characteristic and foulants  on hydrophobicity and surface charge in microfiltration process. Meinders et al.44 investigated the deposition efficiencies and reversibility of bacterial adhesion on various substratum surfaces and then found bacterial adhesion to the surface was more accurately described by the XDLVO approach. In the study of Kumar and Ting,45 they observed the presence of streptomycin increased biofilm formation by Staphylococcus aureus and Pseudomonas aeruginosa due to the changes in cell surface characteristics. Therefore, the microbial surface thermodynamic theories based on DLVO and XDLVO are the fundamental and accurate approaches to analyse and predict biofilm formation and aggregation.46The classical DLVO theory, which includes two types of interactions, namely van der Waals (LW) and electrostatic double layer interactions (EL), is often proposed to describe the stability of colloidal suspensions and colloidal membrane fouling in the field of colloid chemistry.Bacillus subtilis, which has been widely studied as a representative bacterium for biofilm formation.47–49 We investigated the inhibitory effectiveness of TCS on biofilm formation in a wide concentration range and found the effective concentration was as low as 100 μg L−1. The bacterial surface characteristics and thermodynamic properties were evaluated by DLVO and XDLVO theories to elucidate the variation of bacterial surface interaction energy induced by TCS. This study aimed to investigate the potential inhibitory mechanism of metabolic uncoupler on biofilm and biofloc through surface characteristics and thermodynamic analysis. The results in this investigation might be helpful to further understand the relationship between bacterial surface characteristics and biofilm formation, which can promote the development of biofouling control approach based on metabolic uncoupler.Herein, this study systematically analysed and evaluated the effect of a typical uncoupler, TCS, on biofilm formation, aggregation, flocculability, surface characteristics and thermodynamic properties of a Gram-positive bacteria, 2.2.1B. subtilis (ATCC6051) was used in this study. B. subtilis is a common typical bacterium for biofilm studies.48,49 TCS (99%) was purchased from Acros Organics (Belgium). B. subtilis first cultivated in Tryptic Soy Agar (TSA) media in Petri dishes, stored at 4 °C and re-inoculated every week. Before each experiment, a 15 ml centrifuge tube containing 6 ml TSB (tryptic soy broth) liquid medium was inoculated with cell from the stock plate, and incubated at 37 °C for 24 h to late exponential phase until OD595 = 0.8 (∼108 CFU ml−1). Prior to use, the cultivated bacteria in TSB media were centrifuged and washed twice with PBS buffer. The accurate bacteria concentration was measured by OD595 and plate counting using TSA plates. All other chemicals used were analytical grade, and solutions were prepared with ultrapure water .The Gram-positive bacteria strain 2.2B. subtilis in order to control difference induced by sample handing. In this study, the microbial biofilm were cultivated in TSB media in polystyrene 96-well plates . Microtiter wells were seeded with 200 μl bacterial suspension with an initial concentration of 2 × 106 CFU ml−1. One 96 well plate, columns 1 to 3 were applied as blank (TSB media only), columns 3 to 4 were used as the control (without TCS addition) and columns 5 to 10 were applied as experimental group (with different TCS concentrations). The composition in each well is shown in ESI.Biofilm cultivation conditions were aimed to produce microcolony or biofilm of 2.36 CFU ml−1. These tubes with or without TCS were then incubated at 37 °C with shaking at 150 rpm. After 24 h incubation, particle size distributions of the bacterial suspension in each tube were obtained using Mastersizer 2000 . d (0.5) is the median diameter. All cell samples were prepared in triplicate and particle size measurements for each sample were run in triplicate.In this study, 50 ml centrifuge tubes were seeded with 20 ml TSB medium with an initial bacterial concentration of 2 × 10B. subtilis cells with or without TCS were incubated for 24 h at 37 °C with shaking at 150 rpm. Then the B. subtilis treated by centrifugation at 12 000 rpm for 10 min and washed twice by 0.1 M NaCl solution. After discarding supernatant, cell pellets were re-suspended in NaCl solution with different concentrations and the absorbance of cell suspension was measured at 650 nm (A0). The rest of cell suspensions were centrifuged at 1000 rpm for 2 min, and then measured the optical density at 650 nm (At). All cell samples were prepared in parallel and OD650 measurements for each sample were run in triplicate. The calculation formula of F can be written as:37In the test of flocculation, 2.4B. subtilis cells in NaCl solution with gradient concentrations were harvested by the same method of flocculation test. The zeta potential of each sample was measured by a Zetasizer Nano ZS Instrument  at room temperature. After 24 h incubation of B. subtilis cells with or without TCS at 37 °C with shaking at 150 rpm. All cell samples in this portion were prepared in parallel and zeta potential measurements for each sample were in triplicate.B. subtilis cells were first incubated with or without TCS for 24 h, and then homogeneous cellular layers were gained on 0.45 μm acetate cellulose membranes by suction filtration. These samples were washed twice by DI water and then placed into Petri dishes for 12 h in dehydrator. The measurements of contact angles were used by sessile drop approach with a drop of ultrapure water, formamide, and 1-bromonaphthalene. All cellular layer samples were prepared in parallel and contact angle values for each sample were based on arithmetic means of at least ten independent measurements.In the process of contact angle measurement, 2.5WDLVOTOT is the total interaction energy between two colloids in liquid predicted by DLVO theory, WLW is the LW interaction term and WEL is the EL interaction term.In this study, the DLVO theory indicates the total interaction energy between two colloids as the sum energy of van der Waals (LW) and electrostatic (EL) interaction.50 suggested that the energy balances performed for aqueous systems must account for the acid and base interaction energy in addition to the LW and EL interaction energy. Considering the AB interaction energy, the XDLVO approach can be written asWE−DLVOTOT is the total interaction energy between two bacterial cells immersed in water predicted by XDLVO approach and WAB is the AB interaction term.Later, van OssThe detailed calculations for the terms in the DLVO and XDLVO theories are shown in ESI.†2.66 CFU ml−1. These tubes with or without TCS were then incubated at 37 °C with shaking at 150 rpm. After 24 h incubation, 20 ml of bacterial liquid media was centrifuged at 8000g for 15 min at 4 °C. Cell pellet left in the centrifuge tube was re-suspended to its original volume by NaCl solution (0.05% w/w). The cell suspension was placed in a water bath at 60 °C for 30 min, and then centrifuged at 8000g for 15 min at 4 °C. The organic matter in the supernatant was regard as EPS. The analysis of EPS by chemical methods mainly measured the contents of proteins and polysaccharides which were considered as the dominant components of EPS. The measurement of proteins was measured by the modified BCA assay and the concentration of polysaccharides was evaluated by phenol-sulfate acid method. All EPS samples were prepared in parallel and measurements of EPS samples were conducted in triplicate and the mean value was presented.In this study, 50 ml centrifuge tube was seeded with 20 ml TSB medium with an initial bacterial concentration of 2 × 102.7t tests with a significance level of 95%  showed by *.Means and standard errors for all experiments were calculated at each test point using Microsoft Excel. Data shown in the graphics was analysed by independent sample 3.3.1B. subtilis. The schematic of biofilm development shown in Fig. S1.†−1 to 10 μg L−1. In contrast, few biofilm was observed in the test group with TCS concentration at 100 μg L−1. Crystal violet approach was applied to quantify the formed biofilm in different TCS concentration and the results are shown in 595 values of control samples and test samples with TCS concentration from 10 ng L−1 to 10 μg L−1 were around 1.0. However, after 24 h incubation and stained by crystal violet, the OD595 decreased to only about 0.5 in the wells with TCS (100 μg L−1). The inhibition effectiveness of TCS on biofilm formation by 24 h incubation is shown in −1 did not induce significant reduction of B. subtilis biofilm. When TCS concentration increased from 10 μg L−1 to 100 μg L−1, the biofilm formation was significantly reduced by over 50%. In fact, there are a great number of attached cells at the bottom of a well could not be directly observed by eyes, but these cells could be stained by crystal violet. In addition, it was observed that TCS at 100 μg L−1 did not significantly impair the growth of B. subtilis  obviously inhibited the formation of aerobic granular.34 However, it was also reported that TCS over 1 mg L−1 directly induced sludge reduction in activated sludge system.23,33 It is notable that in this study, we found that lower TCS concentration (100 μg L−1) inhibited the biofilm formation of B. subtilis without the inhibition of bacterial growth. In other words, the inhibitory function of TCS on biofilm formation at low concentration was not induced by the growth inhibition. This found implied the application of TCS at 100 μg L−1 for biofilm inhibition can be considered as a kind of biological biofouling control approach.The effect of TCS on bacterial biofilm formation was studied in a wide concentration range using a Gram-positive bacterium, 3.2B. subtilis biofloc after 24 h incubation with or without TCS addition were shown in −1 TCS sample, indicating that the formation of biofloc and cells aggregation was substantially inhibited by 100 μg L−1 TCS. This result suggested that the bacteria aggregation was repressed or the biofloc tended to disperse when bacteria incubated with TCS at 100 μg L−1. In addition, the value of d (0.5) in test sample with 100 μg L−1 TCS was apparently lower than that of control, which also suggested the formation of B. subtilis biofloc was affected by TCS at 100 μg L−1. Meanwhile, the particle size distribution of other test groups were similar with that of control.The particle size distributions of 3.339,51B. subtilis cells incubated with or without TCS after 24 h. The concentrations of polysaccharides and proteins in EPS were not affected by TCS at the concentration from 10 ng L−1 to 10 μg L−1, implying the secretion of EPS was not affected by TCS at these concentrations. However, the apparent reduction in the contents of proteins and polysaccharides in EPS extracted from B. subtilis cells after 24 h exposure to 100 μg L−1 TCS was observed in −1 TCS which contributed to the reduction of biofilm and biofloc particle size. Some previous studies23,33 reported that dosing 1 mg L−1 TCS in activated sludge inhibited the normal growth of sludge and increased the secretion of EPS and soluble microbial products (SMP) which might be because the defence mechanism were stimulated by the presence of TCS. However, this study found that the presence of TCS at 100 μg L−1 did not inhibit the growth of B. subtilis and only control the process of biofilm formation, implying the defence mechanism was not motivated. Jiang and Liu34 suggested that under energy deprivation condition, microorganisms would first satisfy their basic metabolic requirements compared to synthesis of “luxury” macromolecules, such as EPS. Therefore, TCS at different concentrations may induce different effects on microbial EPS production.Give the importance of EPS in the process of biofloc and biofilm formation,3.452 After 24 h incubation of B. subtilis with or without TCS, the values of zeta potential in bacterial re-suspended solution with gradient concentration of NaCl were shown in −1 to 10 μg L−1 were similar with control. However, the zeta potential in test group (100 μg L−1 TCS) increased from −48.66 to −9.03 mV with the same NaCl concentration variation. It was observed that the zeta potential at each point of NaCl concentration in the test group (100 μg L−1 TCS) was more negative than that of the control group. This finding indicated that the presence of 100 μg L−1 TCS in bacterial growth phase induced the changes of bacterial surface charge. The more negative surface charge might be induced by the changes of EPS secretion.39 In addition, the difference of zeta potential between control sample and 100 μg L−1 TCS sample decreased with an increase in ionic strength. Generally, the bacteria with more negative charge is expected for lower membrane fouling tendency in membrane filtration system.32 The zeta potential of B. subtilis after 24 h incubation with 100 μg L−1 TCS was more negative than that of control, suggesting that the presence of 100 μg L−1 TCS during the process of cell culture enhanced the cell surface negative charge. This result could be an important cause for the reduction of the biofloc particle size and biofilm in previous sections.Zeta potential is an important parameter which characterizes the physicochemical properties of bacterial cell surface and has a tight relationship with bacterial aggregation and disaggregation processes.B. subtilis re-suspended in different NaCl concentration solution. A higher F value indicates a less stable cell suspension and also means a stronger flocculability of bacterial cells. The F values in the control group and test groups increased with the increasing electrolyte concentration from 0.001 to 0.1 M which implied the increase of ionic strength within limits could improve the flocculability of B. subtilis. As the result in zeta potential measurements, the zeta potential decreased with the increase of ionic strength and therefore, caused the reduced contribution of electrostatic repulsive interaction between two cells. However, the increasing tendencies of flocculability in the control group and test groups were both reversed when the NaCl concentration over 0.1 M. This contradictory phenomenon should be due to the occurrence of “hydrophobization” and “salting out” in high salt solution.53 Notably, the flocculability of B. subtilis incubated with 100 μg L−1 TCS was evidently worse than that of control and other test groups. The reduction of flocculability was consisted with the difference of zeta potential, indicating the weaken flocculability of B. subtilis incubated with TCS (100 μg L−1) was attributed to its more negative surface charge in low ionic strength solution. However, the difference of flocculability between the control and TCS sample (100 μg L−1) was reduced due to the NaCl concentration over 0.1 M. This variation should be induced by the lower contribution of the double layer interaction and dehydration at higher ionic strength.3.537,46 As shown in B. subtilis which were incubated with or without TCS. Generally, contact angle divided into two categories: θw < 90° is wetting and θw > 90° is non-wetting. It is important to indicate that the hydrophobic interactions between two surfaces become effective at θw > 65° and the hydrophilic interactions at θw < 65°.54 In this study, the contact angles of control group and test groups were all below 65°, suggesting that all B. subtilis surfaces were hydrophilic and hydrophilic interactions were dominant between B. subtilis cells and water. However, the contact angle of B. subtilis in the control group and cells incubated with TCS (100 μg L−1) were obviously different, implying the presence of TCS (100 μg L−1) could increase the hydrophilicity of B. subtilis cells. Xie et al.55 reported that the increase of water contact angle was favourable for the formation of biofloc. Therefore, the decreased water contact angle observed in 100 μg L−1 TCS sample would be unbeneficial for the formation of biofloc and biofilm. Moreover, the contact angles of test groups with TCS from 10 ng L−1 to 10 μg L−1 were not significantly changed.The surface characteristics of bacteria such as contact angle and surface charge have significant effect on bacterial hydrophobicity and flocculability.B. subtilis cells cultured with or without 100 μg L−1 TCS were calculated and showed in −1) had high electron donor components (γB−) and relatively low electro acceptor components (γB+), indicating the B. subtilis cells were typically characterized by a high electron donor monopolarity. The polar component (γABB) had a little decrease from control sample to test sample (100 μg L−1 TCS) indicating the AB interaction between two B. subtilis cells was affected by TCS presence. The interfacial free energy (ΔGad) values in 38 Positive values of the interfacial free energy represent the hydrophilic surfaces, while negative values indicate the hydrophobic surfaces. The ΔGad of test sample (TCS at 100 μg L−1) was more positive than that of control sample, also suggesting that the bacterial surface of B. subtilis incubated with TCS (100 μg L−1) was more hydrophilicity. Generally, the cell surface with more hydrophobicity is more easily to form biofilm and biofouling on membrane surface56 and therefore, the effect of TCS on B. subtilis cells surficial hydrophobicity/hydrophilicity might play an important role in the process of biofilm inhibition.Based on contact angle measurements, surface tension parameters and interfacial free energy of 3.655 In the DLVO theory, the van der Waals attraction decreases as an inverse power of the distance between the particles, and the electrostatic repulsive energy is an approximately exponential function of the distance between the cell particles.41 The effects of 100 μg L−1 TCS on WLW and WEL in the prediction of DLVO are described in B. subtilis cells incubated with or without 100 μg L−1 TCS as a function of the separation distance between bacterial cells. As shown B. subtilis cells incubated with or without TCS are similar at large separation distances (>8 nm). In two samples, at separation distance smaller than 8 nm, the EL repulsion dominated and the total interaction was repulsive. In the total interaction energy profiles, the existence of the primary energy maximum plays important role in determining the aggregation of bacterial cells.56 Bacterial cells can overcome the primary energy barrier and then fall into a deep primary energy minimum at very close contact and aggregate irreversibly.57 However, if bacteria cells cannot overcome the energy barrier, they would not aggregate with other cells. Therefore, a higher primary energy barrier implies a more stable bacterial suspension and more resisting aggregation and biofilm formation. The primary energy maximum of B. subtilis cells incubated as control (1564.29 kT) was evidently less than that of B. subtilis cells incubated with TCS at 100 μg L−1 (2194.07 kT). This variation indicated that when B. subtilis cells incubated with TCS (100 μg L−1), bacteria must consume more energy to overcome energy barrier to aggregate than the control cells. In this respect, the bacteria cells with higher primary energy barrier would be expected for poor flocculability and biofilm formation. The prediction of the control sample and test sample (100 μg L−1 TCS) by DLVO approach was consistent with the analysed results in biofilm, biofloc particle size and flocculability tests.The flocculation stability and aggregation of bacterial cells could be predicted from the interaction energy between bacterial cells.45 The effect of 100 μg L−1 TCS on WAB in the prediction of XDLVO and the XDLVO interaction energy profiles of B. subtilis cells incubated with or without TCS as a function of the separation distance were shown in −1), the XDLVO approach predicted repulsion which was agreement with the DLVO theory prediction. However, the primary energy barriers in the control group and test group showed obvious increment due to the addition of AB interaction. The primary energy barrier of B. subtilis cells incubated with TCS at 100 μg L−1 (2557.04 kT) was significantly higher than that of the control (1731.99 kT) and the difference of barrier got larger compared with DLVO prediction. In XDLVO prediction, the increment of primary energy barrier induced by 100 μg L−1 TCS suggested that the bacterial cells incubated with TCS (100 μg L−1) would overcome higher primary energy barriers to aggregate or develop biofilm compared with the prediction of DLVO. In addition, compared with DLVO theory, the total interaction energy barrier increased apparently in the control and test group through XDLVO calculation, indicating that the AB interaction played an important role in B. subtilis cells interaction. This prediction by XDLVO theory indicated a better flocculability and biofilm formation would be observed in the control group compared to the test group (100 μg L−1 TCS)  .4.B. subtilis, suggesting it was perspective in the investigation for biofilm control. Compared to the control, smaller biofloc, poorer flocculability, more negative surface charge and higher hydrophilicity were observed in the test sample after treated with 100 μg L−1 TCS. This study indicated that B. subtilis cells incubated with TCS at optimal concentration need to consume more energy to overcome the primary energy barrier, so as to aggregate or develop biofilm as predicted by DLVO and XDLVO. The analysis of cell interaction energy and surficial characteristics induced by TCS addition provided deeper understanding of the biofilm control process and biofilm inhibitory mechanism based on metabolic uncoupler.Low-dose of TCS was found to effectively inhibit the biofilm formation and secretion of EPS by There are no conflicts to declare.RA-008-C8RA02315H-s001


For patients with single sided deafness (SSD) or severe asymmetric sensorineural hearing loss (ASHL), cochlear implantation remains the only solution to restore bilateral hearing capacity. Prognostically, the duration of hearing loss in terms of audiological outcome is not yet clear. Therefore, the aim of this study was to retrospectively investigate the influence of subjective deafness duration on postoperative speech perception after cochlear implantation for SSD as well as its impact on quality of life.The present study included a total of 36 adults aged 50.2 ± 15.5 years who underwent CI for SSD/ASHL at our clinic between 2010 and 2015. Patients were audiometrically assessed at 3 and 12–36 months postoperatively. Test results were correlated with self-reported duration of deafness. Quality of life was assessed by questionnaire.p = 0.001) and to 50% after 12–36 months (p = 0.002). There was a significant correlation between audiometric outcome and subjective deafness duration at 12–36 months postoperatively  with a cutoff for open-set monosyllable recognition at a duration of deafness of greater than 408 months. Quality of life was significantly improved by CI.Mean duration of deafness was 193.9 ± 185.7 months. The side-separated hearing threshold showed an averaged target range between 30 and 40 dB HL. Freiburg monosyllable test increased from 0% pre-operatively to 20% after 3 months (CI implantation in unilaterally deafened patients provides objective and subjective benefits. Duration of deafness is unlikely to be an independent negative predictive factor and thus should not generally be considered as contraindication. Patients with single sided deafness (SSD) and a normal-hearing contralateral ear are severely limited in various aspects of their daily lives . These lIn acquired single sided deafness (SSD), a cochlear implant (CI) is the best possible treatment option to largely restore binaural hearing in affected patients. CI provision is also widely established in congenital born unilaterally deaf children –9. In adAn influence of the normal-hearing opposite ear as an influence of central speech processing in SSD patients is shown by significantly worse hearing in the better ear compared to the age-correlated normal-hearing (NH) comparison group .Predictive factors for hearing rehabilitation success via cochlear implantation are widely reported. Duration of deafness is a recognized factor in predicting hearing success –17. ThisIn the present study, hearing rehabilitation in SSD by means of CI fitting is further investigated within the framework of a retrospective data analysis. For this purpose, 36 patients were identified who were fitted with a CI for SSD at the Department of Otorhinolaryngology of the University Medical Center of the Johannes Gutenberg University Mainz between 2010 and 2015.Patient specific data with regard to date of birth, gender, self-reported duration of deafness, side of deafness, cause of deafness, history of hearing aid/CROS fitting, history of tinnitus complaints, date of surgery, implant and electrode type, as well as audiometric data and subjective patient satisfaction were recorded.Follow-up audiometric data were collected and analyzed at 3 months and at 12–36 months after surgery. Quality of life was assessed by questionnaire.All patients who were evaluated underwent comprehensive audiological examinations as part of the preliminary examinations for cochlear implantation. The examinations were performed in soundproof booths with calibrated audiometers.Pure-tone audiometry for air- and bone-conduction was tested separately for both ears at the following frequencies: 125, 250, 500, 1000, 2000, 3000, 4000, 6000, and 8000. Masking of the better hearing ear was performed to rule out cross hearing using narrowband noise. If no hearing threshold could be recorded due to deafness, the hearing threshold at this frequency was set to the value of 130 dB to perform a statistical evaluation of the hearing threshold.For the evaluation of speech intelligibility in quiet, the Freiburg speech intelligibility test (using monosyllables and numbers) according to Hahlbrock –20 was uin Single Sided Deafness Questionnaire (BBSS) [Quality of life was assessed with the Bern Benefit e (BBSS) . The tesp-values < 0.05 were considered significant and < 0.01 as highly significant. The Wilcoxon signed rank test was used for intergroup comparison, and the one-sample signed rank test was used for the intragroup test. Correlation was calculated according to Pearson (two-tailed). Results are presented as median or rounded mean values with the respective standard deviation (± SD), unless otherwise indicated.The statistical analysis of the results and the comparison of the individual groups with each other were carried out using non-parametric rank tests with the aid of SPSS software . Here, In the present study, data of 36 patients  were retrospectively collected and analyzed who were fitted with a CI due to acquired SSD or asymmetric sensorineural hearing loss. All patients were fitted with CROS- or high power hearing aids depending upon residual hearing capacities. The mean age at implantation was 50.2 ± 15.5 years. 22 (61.1%) patients received left-sided and 14 (38.9%) right-sided CIs.22 61.1%) of the patients were implanted with a MED-EL CI system from MED-EL and 14 (38.9%) with a cochlear CI system. The tabular listing of the electrode array used in combination with the implant in each case and the corresponding frequency distribution is shown in Table .1% of thThe mean self-reported duration of deafness of the patients before cochlear implantation was 193.9 ± 185.7 months . The following causes for deafness were reported: Hearing loss (58.3%), congenital progressive hearing loss (11.1%), acoustic neuroma (8.3%), tympanoplasty (8.3%), and temporal bone fracture (5.6%).More than two thirds of the patients (66.7%) complained of tinnitus symptoms in addition to unilateral hearing loss. One third (33.3%) of the patients described a tinnitus ipsilateral to the deafness, 27.8% a bilateral tinnitus and 5.6% a contralateral manifestation.loss . The median hearing loss across all 9 measured test frequencies is 39.0 dB HL in the non-implanted ear and 100.5 dB HL in the implanted ear.Figure Figure p < 0.001) and from 90 to 100% in the long-term course (p > 0.05). The result in the Freiburg monosyllable test increases from 0% pre-operatively to 20% after 3 months (p = 0.001) and from 20 to 50% in the long-term course (p = 0.002). 50% of the patients show a percentage of monosyllable comprehension in the long-term course between 30 and 60%.The result in the Freiburg number test shows a significant increase from a median of 0% to 90% after 3 months  is shown for the time point 3 months and a highly significant correlation  for the time point 12–36 months  to 20% in the first three months and to 50% for the period 12–36 months. The data of this evaluation show a slightly more favorable speech understanding than the data published by Sullivan et al. using the consonant-nucleus-consonant (CNC) speech test with results of 32% and 30% for the time points 3 and 6 months after implantation to about 35% for the period 12–36 months. . On averIt should be emphasized that the significant improvement in speech understanding between the periods 3 months postoperatively and 12–36 months postoperatively shown in the present collective is accompanied by no change in the hearing threshold in the inflation curve. This is most likely to be explained by training effects of the parallel audioverbal therapy or by an improvement of central auditory processing, respectively, and is in accordance with the literature , 25.The main question of this work was the relationship between self-reported duration of deafness and postoperative monosyllabic comprehension.r = − 0.294; p > 0.05). In accordance with the a results of other study groups, no correlation between deafness duration and speech understanding can be identified in the present collective at this time [First, the result after 3 months postoperatively was considered as an approximation. Here, the analysis of the linear regression according to Pearson showed a tendency towards a negative correlation between self-reported duration of deafness and postoperative outcome in the Freiburg monosyllable comprehension, however, without reaching significance level . This result is supported by the individual analysis of the single cases. At 3 months postoperatively, only one out of seven patients (14.3%) with a self-reported duration of deafness greater than 400 months yielded a monosyllabic understanding of ≥ 30%. At 12–36 months, this ratio increased to two out of seven patients (28.6%) while one patient was able to achieve a monosyllabic understanding of 10%. Consequently, four out of seven patients (57.1%) with a self-reported duration of deafness greater than 400 months showed no monosyllabic understanding. However, for deafness durations of less than 400 months, 28 of 29 patients (96.6%) were able to achieve a monosyllabic understanding of ≥ 30%. In case of a self-reported duration of deafness of less than 156 months, a majority of patients (85.7%) who had no open monosyllabic understanding at 3 months showed monosyllabic understanding of ≥ 30% at 12–36 months. Accordingly, the prognosis for successful hearing rehabilitation with CI in our collective can be assumed to be favorable for deafness durations of less than 400 months. Successful hearing rehabilitation with CI for longer deafness durations must be regarded as clearly limited but nevertheless feasible. In line with this, Nassiri et al. could not find any difference in the hearing success of SSD patients with CI between a deafness duration of more or less than 10 years [Looking at the results of the linear regression analysis 12–36 months after CI fitting, there is a clear and highly significant correlation between self-reported duration of deafness and speech understanding after CI fitting  or BiCROS hearing aids, or implantable bone conduction hearing systems were available for these patients until then, the newly established indication resulted in a large collective of long-term deafened patients for whom the option of CI was available for the first time. Accordingly, the number of patients with long-term deafness presenting for CI evaluation could potentially be expected to decline in the coming decades against the background of widespread availability of CI fitting.Patients with above-average deafness duration represent a phenomenon CI clinics in general were confronted with after the establishment of the indication for CI in SSD patients in 2008 . Since oThe study of quality of life represents an important endpoint for a health and medical research . PatientThe patients with SSD rated their hearing impression with CI better than compared to their condition preoperatively without CI. Thus, the median values of all questioned items are shifted to the right on the scale, which reflects a more positive hearing impression with hearing aid. Overall, the answers are relatively homogeneous with interquartile range values also in the positive range (range between 25 and 75%).best aided condition" with CI and normal hearing on the opposite side, certainly absorb music more with the normal hearing ear.Several studies show that hearing via CI can result in limited music enjoyment due to the technical limitations of a CI , 36. TheQuestion 7 "Conversation in reverberant rooms" is rated as the most difficult situation with a CI at the median in the BBSS. Conversation in reverberant rooms is also rated as a difficult listening situation in other studies , 38.The result of question 10 with the item "Overall impression of hearing" is gratifying. The improvement shown here for unilaterally deafened patients after implantation with a CI is also evident in other studies such as Jacob et al. and Prejban et al. , 40. ForLimitations of the present study are primarily due to the study design. This was a retrospective patient population from a single CI center. Due to the retrospective study design, audiometric control was not available for all patients at uniform time points. This resulted in the comparison three months postoperatively, which was available for all patients, and 12–36 months postoperatively. In addition, Oldenburg sentence test results were available for only a small proportion of patients, so that only the Freiburg sentence tests available for all patients were evaluated. Consequently, no statements can be made about the significantly more demanding hearing in noise.Bone Anchored Hearing Aid (BAHA).Patients with SSD and ASHL of different etiologies were also included. Accordingly, it is not possible to differentiate between the influence of SSD or ASHL on hearing success with CI. In addition, a considerable proportion of patients had unusually long subjective deafness durations due to the newly established indication for CI in SSD. Furthermore, etiologies of hearing impairment were present, which in addition to cochlear hearing loss may also cause neural or central hearing impairment. In conclusion, the BBBS questionnaire used to assess quality of life after unilateral CI fitting is basically developed for assessment after fitting using Overall, this work showed that CI implantation in unilaterally deafened patients provides objective and subjective benefits. The current research findings support these results and show that the use of a CI in SSD will continue to increase in the future.Based on these findings, the subjective duration of deafness before implantation in the deafened ear alone should not be the sole contraindication against CI in SSD. It is still not clear which preoperative factors are a precise predictor for the postoperative speech understanding in individual cases.In perspective, the targeted use of patient-specific anatomical  and physiological data  and their inclusion in speech processing strategies will also lead to a better more realistic mapping of the acoustic situation during electrical stimulation via the CI , 42.


Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a rare acquired immune-mediated neuropathy. Although microbial infection is potentially a contributing factor, a causative link between CIDP and microbial infection remains unclear. There is also no definitive biomarker for CIDP diagnostics and therapies. The present study aimed to characterize the serum metabolic profile and gut microbiome structure in CIDP.Targeted metabolomics profiling of serum, using liquid chromatography-mass spectrometry, and metagenomics sequencing of stool samples from a cohort of CIDP and non-CIDP subjects were performed to evaluate serum metabolic profiles and gut microbiome structure in CIDP subjects relative to healthy controls.Klebsiella pneumonia and Megamonas funiformis, and genes involved in bacterial infection were notably more abundant in CIDP subjects, while gut microbes related to biotransformation of secondary bile acids were abnormal in CIDP versus non-CIDP subjects. Correlation analysis revealed that changes in secondary bile acids were associated with altered gut microbes, including Bacteroides ovatus, Bacteroides caccae, and Ruminococcus gnavus.Metabolome data revealed that the bile acids profile was perturbed in CIDP with bile acids and arachidonic acid enriched significantly in CIDP versus non-CIDP controls. Metagenome data revealed that opportunistic pathogens, such as Bile acids and arachidonic acid metabolism were disturbed in CIDP subjects and might be affected by the dysbiosis of gut microbial flora. These findings suggest that the combination of bile acids and arachidonic acid could be used as a CIDP biomarker and that modulation of gut microbiota might impact the clinical course of CIDP.The online version contains supplementary material available at 10.1186/s13578-023-00956-1. Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a rare, acquired, and immune-mediated demyelinating neuropathy causing limb weakness and sensory deficits . The cauCampylobacter jejuni infection is known to be the pathophysiological basis of neural involvement leading to GBS [Another type of immune-mediated demyelinating neuropathy, Guillain Barre syndrome (GBS), also named acute inflammatory demyelinating polyradiculoneuropathy, was reported to be related to microbial infection , 12. Theg to GBS , 15. In g to GBS –19, whilg to GBS , 21. HowTo address the above knowledge gap, an unbiased approach was taken to identify serum metabolites and gut microbial flora that were significantly changed in CIDP subjects relative to non-CIDP controls. To that end, untargeted metabolomics profiling of serum, using liquid chromatography-mass spectrometry (LC–MS), was performed to discover potential biomarkers for CIDP, and metagenomics analysis of gut microbial species and genes in stool samples was performed to discover the association between CIDP and gut microbial flora. Additionally, Pearson’s correlation analysis was performed to explore the association between the bile acids (BAs) profile and the microbiotic abundance in the gut. Our findings provide an improved understanding of perturbations of the metabolome-microbiome interface in CIDP, including identification of potential biomarkers to monitor ongoing CIDP activity and modulation of gut microbiota to prevent CIDP.A total of 64 subjects, including 31 CIDP patients and 33 age- and sex-matched healthy controls  tandem Q Exactive high-resolution mass spectrometer  for separation and detection of metabolites. Chromatographic separation was performed on a Waters ACQUITY UPLC BEH C18 column , with a column temperature of 45 °C. The mobile phase consisted of 0.1% formic acid and acetonitrile in the positive mode and 10 mM ammonium formate and acetonitrile in the negative mode. The mass spectrometric settings for positive or negative ionization modes were as follows: spray voltage, 3.8/ − 3.2 kV; sheath gas flow rate, 40 arbitrary units (arb); aux gas flow rate, 10 arb; aux gas heater temperature, 350 °C; capillary temperature, 320 °C. The full scan range was 70–1050 m/z with a resolution of 70,000, and the automatic gain control (AGC) target for MS acquisitions was set to 3e6 with a maximum ion injection time of 100 ms.A PCA model  was estaA PLS-DA  model beMetagenomic extraction and metagenomics sequencing were performed at the BGI Co., Ltd. . Stool metagenomic DNA extractions were performed using the MolPure® Stool DNA Kit . Metagenomic libraries were sequenced on the DNBSEQ platform. High-quality short reads of each DNA sample were assembled by MEGAHIT .MetaGeneMark  was usedNMDS was conducted as previously described , and ANOt-test was performed to compare the CIDP and non-CIDP groups. Correlations between the gut microbial abundance and BAs profile were estimated using Pearson’s correlation analysis.All statistical analyses were performed using GraphPad Prism 9.0 software. A two-tailed To characterize the metabolomic profile in CIDP, each serum sample was analyzed by LC–MS/MS in non-targeted mode, and MS/MS was performed using sensitive, high-resolution MS to collect data from both positive and negative ionization modes to improve metabolite coverage. A total of 4739 different metabolites were detected in positive ion mode, among which 1736 metabolites were identified, and 1504 different metabolites were detected in negative ion mode, with 744 metabolites identified. To determine whether there were significant differences in metabolites between the CIDP and non-CIDP groups, a PCA model was established to observe the distribution and separation trend of the two groups of samples  and TXB2 (p = 0.4702) in CIDP patients with or without cardiovascular disease, whereas the relative abundance of AA (p < 0.0001 and p < 0.0001) and TXB2 (p = 0.0007 and p = 0.0003) differed significantly between the non-CIDP group and CIDP group regardless of the presence of cardiovascular disease  and the mediator in AA metabolism  are reported to be involved in different neurological disorders and cardiovascular diseases –38. In tMetabolic pathway enrichment analysis was performed based on the KEGG database, and differentially abundant metabolites and their pathways identified in negative and positive ion modes were evaluated  size and taxonomic abundance of the samples. The rarefaction curve of CIDP and non-CIDP group tended to be steady , Megamonas (Selenomonadaceae), and Phascolarctobacterium (Acidaminococcaceae), while Bacteroides (Bacteroidaceae) and Phocaeicola (Bacteroidaceae) had reduced abundance , Escherichia coli (Enterobacteriaceae), Megamonas funiformis (Selenomonadaceae), and Phascolarctobacterium faecium (Acidaminococcaceae), while Phocaeicola dorei (Bacteroidaceae), Phocaeicola vulgatus (Bacteroidaceae), Bacteroides uniformis (Bacteroidaceae), and Bacteroides sp. A1C1 (Bacteroidaceae) decreased  had 1–3 types of above enriched microorganisms with levels higher than 1% at family, genus, and species levels, including Klebsiella pneumonia, Escherichia coli, and Megamonas funiformis in CIDP, eighteen genes involved in bacterial infection, nine genes involved in bacterial invasion, three genes involved in quorum sensing were enriched in CIDP , Escherichia coli (Enterobacteriaceae), Megamonas funiformis (Selenomonadaceae), and Phascolarctobacterium faecium (Acidaminococcaceae) were the most enriched species in group CIDP, and Wilcoxon rank-sum test analysis indicated that Klebsiella pneumoniae was the most significantly differing species between the CIDP and non-CIDP groups in terms of abundance. Many virulence factor-encoding genes and infection-related genes were enriched in CIDP subjects  and then transformed into secondary BAs through microbial hydroxysteroid dehydrogenases, which are widely found in the gut microbiota, including rococcus –65. Howetierella –68, Diasorangium , and Pyt[Pythium , and bacmaritime . In thisBacteroides  was much lower in the stool samples of the CIDP subjects than non-CIDP subjects, while pathogenic bacteria such as Klebsiella pneumonia (Enterobacteriaceae) were enriched in the stool samples of the CIDP subjects. KEGG annotation of metagenomic data also revealed that genes involved in bacterial infection and disease were enriched in CIDP subjects. These findings indicate that the normal microbiota-host interactions are disturbed with CIDP.Microbes in healthy human guts belong to a small number of families, mainly dominated by Bacteroidetes and Firmicutes , 73. HerClostridium species as probiotics to impact human heath through affecting microbe-host interactions [Lactobacillus gasseri and Lactobacillus acidophilus, which were used as probiotics, and revealed that BA type and BSH substrate preferences affected the growth of these two species [The past few years have brought exciting new insights in the field of probiotic therapies. Guo et al. reviewed the potentials and challenges of using ractions . Foley e species . These rThis study revealed broad metabolic shifts in CIDP subjects versus control subjects, with perturbations in the serum BA profile and significantly increased AA in CIDP. Additionally, the gut microbiome composition was significantly changed in CIDP subjects, and levels of gut microbes related to secondary BA biotransformation were abnormal in CIDP. Our findings suggest that CIDP may be related to alterations in the gut microbiome, including potential infection with pathogens, and that the dysbiosis of gut microbial flora impacts BA and AA metabolism in CIDP subjects. Our findings also suggest that a combination of BAs and AA could be used as a surrogate biomarker of CIDP and that modulation of gut microbiota could impact the CIDP clinical course.Additional file 1: Table S1. The cohort of CIDP patients and healthy controls enrolled in this study. Table S2. Enriched metabolites and their pathways identified in the negative ion mode. Table S3. Enriched metabolites and their pathways identified in the positive ion mode. Table S4. Enriched genes involved in virulence factors in CIDP subjects. Table S5. KEGG 3 pathways with significant changes in gene abundance. Table S6. Enriched genes involved in secretion system in CIDP subjects. Figure S1. Rarefaction curve Boxplot. Abscissa represents for sample size while ordinate represents for number of species in sample. Diversity is limited when sample size is small, which is not reliable to represent for the entire microbiota structure. When rarefaction curve tends to be steady, it indicates that the sampling quantity is sufficient. Figure S2. NMDS and Anosim analysis. Anosim analysis at the family-level (A), genus-level (C) and the species-level (E). Between represents the distance between CIDP and non-CIDP groups, and the remaining boxes represent the distance within the corresponding group. NMDS analysis at the family-level (B), genus-level (D) and the species-level (F). Scales on X-axis and Y-axis on NMDS graph are the projection axes of samples in 2D. Figure S3. Microbial classifications and abundance in individual samples shown at family-level (A), genus-level (B) and the species-level (C). Figure S4. Box plot of enriched pathways in CIDP of KEGG secondary classification. The gene number can be viewed on the X-axis, the secondary classification can be viewed on Y-axis. Figure S5. Comparisons of the relative Eukaryota-Bacteria ratio in the stool of non-CIDP and CIDP group. Data are shown as mean ± SEM.


ZA-8 exhibited the highest fill factor and efficiency of 0.37% and 0.69%, respectively, because of its boosted short-circuit current and open-circuit voltage.This study reports a simple new technique for the preparation of novel hexagonal-shaped mixed metal oxides (MMO) nanorods using Zn/Al-layered double hydroxide (LDH) as a precursor for dye-sensitized solar cell (DSSC) application. The effect of the Zn to Al molar ratio demonstrated a sound correlation between the obtained nanorods’ diameter and the fabricated DSSCs efficiency. Additionally, the optical behavior of the fabricated MMO film as well as the absorption enhancement due to the utilized dye are also demonstrated; a cut-off phenomenon at around 376 nm corresponds to the attained hexagonal nanorods. The open-circuit voltage augmented noticeably from 0.6 to 0.64 V alongside an increase in the diameter of nanorods from 64 to 80 nm. The results indicated that an increment in the diameter of the nanorods is desirable due to the enhanced surface area through which a higher amount of dye N719 was loaded ( Howevications ,16,17,182@MMO” with plate-like morphology; a conversion efficiency of 1.5% was attained due to the active role of TiO2 in the MMO matrix [A number of reports in the literature report the utilization of MMOs-based Zn/Al-LDHs nanostructures for DSSC applications. Zhang et al. demonstrated the occurrence of hexagonal plate-like MMO particles through which the highest efficiency obtained was 0.0129% . The samO matrix . AdditioO matrix . HexagonO matrix . Wang etO matrix . DespiteIn this attempt, this study reports a simple technique for the preparation of novel hexagonal-shaped MMO nanorods using Zn/Al-LDH as a precursor. The obtained MMO nanorod layers were used for the fabrication of photo-electrode for DSSC application. Subsequently, a robust correlation between the diameter of the nanorods, Zn to Al molar ratio, and dye loading amount was established.2+ to Al3+ (m), whereby x M of Zn(NO3)2·6H2O and y M of Al(NO3)3·9H2O under an ambient environment and a constant stirring rate of 750 rpm. Essentially, the pH of the growth solution was preserved at 7 throughout the experiment  for the conservancy of a homogeneous growth matrix. Subsequently, the obtained white precipitate was processed in an autoclave at 65 °C for 8 h to confirm a successful structure growth. Herein, the subsequent solution was later spin-coated on fluorine-doped tin oxide  substrate to form a 1 cm2 layer. The deposition process was repeated for three cycles in which each cycle was subject to an annealing process at 90 °C for 30 min. Phase transformation of the fabricated layers from LDH to MMO was obtained via a thermal treatment process at 350 °C for 1 h with a heating rate of 5 °C/min. Finally, the fabricated layers were denoted as ZA-m, where m designates the molar ratio.Hexagonal-shaped Zn(Al)O-MMO nanorods derived from Zn/Al-LDH were synthesized via a combination of co-precipitation and hydrothermal methods. In particular, Zn/Al-LDH precursor was synthesized as a function of the molar ratio of ZnZA-m layers were immersed in a dye solution containing 5 mM of Ruthenizer 535-bisTBA  for 3 h; the resultant layers were used as the photo-electrode. Afterwards, both the photo-electrode and the counter-electrode were assembled together using an adhesive polymer film , which acts as a sealing and separator element. Hereinafter, electrolyte Iodolyte Z50 redox couple: iodide/triiodide (Solaronix) was fully captivated onto the fabricated electrodes via capillarity.In this study, the Pt electrode (50 nm) was deposited on the FTO substrate using a sputtering technique on the counter electrode. Concurrently, the fabricated −2 under simulated AM 1.5 G sunlight.The thermal stability of the Zn/Al-LDH precursor was investigated via thermogravimetric and differential thermal analysis  with a heating rate of 5 °C/min. The structural and morphological features of the fabricated layers were, respectively, studied using X-ray diffraction  under CuKα radiation and 40 kV, as well as field emission scanning electron microscopy  operated using 1.20 kV accelerating voltage in conjunction with energy dispersive X-ray analysis (EDX). The optical analysis of the fabricated layers was evaluated using UV–vis spectrometry . Finally, the photovoltaic behavior was performed using Keithley 237 SMU  with an output intensity of 100 mW/cmZA-LDH dehydration, and ZnO recrystallization as well as carbonate decomposition.2 structure; this was found to be in accordance with (JCPDS-No:38-0486). Subsequently, the 2D layers structure of LDH collapse, as well as the ZnO crystal formation, can be seen in 3+ within the MMO matrix [3+ in the MMO matrix was confirmed using the EDX technique , while samples ZA-7 and ZA-8 revealed relatively longer hexagonal-nanorods diameters of 75 and 80 nm, respectively. Hence, it is equitable to suggest that there is a direct correlation between the nanorods crystal variation of the deposited MMO and the molar ratio used in this study. The FESEM images also indicate the occurrence of a nanopencil-like morphology, inset in 3+ within the MMO matrix was confirmed through EDX analysis The top-prospective of the deposited hexagonal ZA-8), shifting of absorption edge towards a higher wavelength, the so-called red-shift. Continuously, the absorption spectrum of ZA-8 together with ZA-8 containing N79 sensitizer is demonstrated in ZA-m nanorods evidencing that a larger nanorod diameter leads to advanced N719 loading (The absorbance spectra of the deposited MMO layers are elucidated in ablished d. Partic loading d. Such aThe energy band diagram of the deposited MMO layers and the utilized N719 are presented in ZA-8 exhibited the highest ZA-6 and ZA-7). DSSCs fabricated based on ZA-6 and ZA-7 showed an efficiency of 0.41% and 0.59%, respectively, showing a 20% efficiency enhancement. The demonstrated outcomes agree well with the discussed analysis (FESEM and estimation of dye loading) that a high molar ratio delivers high DSSC performance ; however, an efficiency of 1.02% was reported by Xu et al. using the same materials. It should be mentioned that the aforementioned research group proposed a different structure, sheet-like hexagonal MMO particles. Furthermore, Foruzin et al. revealed the occurrence of efficiency as high as 1.5%, which is mainly due to the active role of TiO2 within the MMO matrix.Continuously, the current density  and efficiency (0.69%), which can be attributed to the enhanced short-circuit current and open-circuit voltage.An easy and new approach for the synthesis of hexagonal MMO nanorods utilizing LDH as a precursor was successfully proposed for DSSC application. The deposited MMO films were characterized using TGA/DTG, XRD, FESEM, and UV-Vis techniques. In particular, the UV-Vis analysis revealed a cut-off phenomenon at 376 nm, which corresponds to the attained hexagonal MMO nanorods. Herein, the effect of the molar ratio between the employed metals (Zn and Al) delivered a pronounced correlation between the microstructural and electrical characteristics of the prepared MMO nanorods and the fabricated DSSCs, respectively. Specifically, increasing the attained MMO nanorods diameter from 64 to 80 nm resulted in higher open-circuit voltage, from 0.6 to 0.64 V, respectively. This was particularly crucial as a larger diameter demonstrated a higher utilized dye N719 loading onto the deposited MMO layers (


Aim: To assess and correlate the hearing system and the Fundamental Frequency (F0) of women who have variable degrees of sensorineural hearing loss. Material and Method: a cross-sectional descriptive study. 30 women with a mean age of 75.95  were included. Inclusion criteria were: symmetric sensorineural hearing loss, a high-frequency sloping configuration, and a type A tympanogram. Subjects underwent Pure Tone Audiometry, a Word Recognition Test, Tympanometry, and Voice Assessment. Results: Patients with higher degrees of hearing loss showed an increased fundamental frequency. Conclusion: In aged individuals with hearing loss, audiovocal monitoring is altered, resulting in voice parameter changes.Increased life expectancy raises demands for special attention for the elderly population; speech, language and hearing science deals with their communication disorders. Hearing loss is a common disorder affecting this age group. It is known that the auditory feedback system is essential to human vocalizing, as it organizes voice production.  F0 is physiologically determined by the number of cycles that vocal folds produce in a second, or the number of repeated glottal cycles.0 for adult women (aged between 18 and 45 years) that speak Brazilian Portuguese is 204 Hz. The F0 decreases with age; in women over 45 years it decreases to about 191 Hz.0 are related not only to anatomical and physiological alterations of the larynx, but also to the difficulty of monitoring voice as a result of age-related hearing loss.Brazilian demography has changed significantly in past decades according to data from the Brazilian Institute of Geography and Statistics.0 values in elderly patients with varying degrees of auditory sensitivity.The aim of this paper was to assess and to correlate hearing and voice F-pure tone audiometry: measuring of air conduction audiometry thresholds at 250 to 8000 Hz and bone conduction auditory thresholds at 500 to 4000 Hz in both ears. The descending method was used for measuring thresholds with both transducers, using audible and inaudible sound, as proposed by Carhart & Jerger.-voice audiometry: investigation of the speech recognition threshold (SRT) and the speech recognition percentage rate (SRPR). The SRT was obtained by a descending procedure using disyllables presented directly. Subjects were asked to repeat the speech stimulus. The lowest intensity level at which subjects recognized 50% of the stimuli - two of four words presented - was defined as the speech recognition threshold. The SRPR, a supraliminar test to establish the listener’s ability to recognize speech stimuli under ideal listening conditions, was investigated using an initial intensity 40 dB over tone threshold means at 500, 1000 and 2000 Hz. If patients reported discomfort, the intensity was reduced in 10 dB steps until the patient reported the best intensity for obtaining the percentage rate of speech recognition. Stimuli were presented orally. The list of 25 phonetically balanced monosyllables we used was proposed by Pen and Mangabeira.-acoustic immitance testing: tympanometry and investigation of contralateral acoustic reflections, done to discard middle ear involvement. Tympanometry permits inferences on the mobility of the tympanic and ossicular systems; acoustic reflection thresholds correspond to the lowest intensity that can alter static compliance.This study was analyzed and approved by the Research Ethics Committee of the Sao Paulo Federal University for research on human beings under the protocol number CEP 1189/04 of the National Health Council. The study sample included 30 female subjects aged between 60 and 93 years  referred from the Geriatrics and Gerontology Institute of the Sao Paulo Federal University (UNIFESP). The evaluation of hearing and voice was done between June 2004 and May 2005. Subjects underwent basic assessments of hearing and voice in an acoustic booth as follows:1.Silman, Silverman2.Lloyd, KaplanAudiometries were classified according to two criteria, as follows:Subjects were instructed to issue the vowel /a/ naturally, at usual intensity and frequency, in a prolonged and sustained manner, and to count the numbers 1 to 10 (sample of connected speech). Voices were recorded in an acoustic booth where maximum noise was 60dB; subjects were seated during recordings. A preamplifier, a VHS stereo HI-FI system and an Audio 20 Plantronic microphone were used for voice recording, as recommended by De Cunto and Menezes (2004).10 Voice samples were digitized at a sample frequency of 32000 Hz using the Sound Forge software, version 4.5. Acoustic analysis was done using the CSL software from Kay Elemetrics Corporation, version 1993/1994, module MVDP, from which the fundamental frequency was extracted.After auditory and voice assessment, data was analyzed statistically using the Kruskal-Wallis, Mann-Whitney, chi-square and equality of two proportions non-parametric tests. The significance level was 0.10 (10%).Starting with pure tone audiometry, right and left ear results were compared to check for symmetry between ears, as published papers have suggested that the left ear performs better in presbyacusis subjects.Hearing and voice systems change with age. The acuity and sensitivity of hearing, and the accuracy, speed, resistance and coordination of voice all decrease with aging. These changes go hand in hand with other bodily changes, and vary from person to person and according to each organism and lifestyle. Studies on the influence of hearing on voice production in the elderly are not frequent in the literature; there have been few studies correlating both systems. There have been reports from authors such as those by Shindo and Hanson0 voice parameter also changes.The fundamental frequency, one of the most studied voice production parameters, may be directly related to the auditory monitoring capability. There are studies showing that when auditory monitoring is altered, the FThe classification of audiometric configurations was also used in parallel with the degree of severity. The gradual configuration (41.3%) predominated, followed by the abrupt configuration , the flat configuration (12.5%) and the sloping configuration (12.5%). These results suggest that the most recurring configuration in the elderly was the gradually sloping type, in which there is an auditory threshold difference between audiogram octaves of more than 5 to 12 dB. Other authors that investigated the same age group have reported that most of the subjects had a downward sloping audiometric configuration where losses occur over 2kHz.18 A study of 331 elderly subjects of both genders also showed that a sloping audiometric configuration was more frequent.0 of sustained issuing of vowel “a”, the sample of connected speech and the degree of hearing loss at low frequencies may be seen. The mean F0for subjects with mild hearing loss (144.44Hz), moderate hearing loss (160.30Hz), moderate-severe hearing loss (188.23Hz) and severe hearing loss (201.27Hz) leads to the conclusion that the F0 value after sustained issuing of the vowel “a” was significantly increased at low frequency hearing loss. No significant difference was found in the comparison of F0 values of the connected speech sample and low frequency degrees. 0 values and high frequencies, where a significant difference was found for both vowel “a” and connected speech. Mean F0 values for sustained issuing of the vowel “a” and the connected speech sample were as follows: 137.22 and 154.32 Hz (mild hearing loss), 154.23 and 189.63 Hz (moderate hearing loss), 174.37 and 183.31 Hz (moderate-severe hearing loss), and 170.02 and 234.16 Hz (severe hearing loss). We noted that F0 is significantly increased in severe high frequency hearing loss both for the sustained vowel and the connected speech sample. There are few published papers relating the F0 voice pattern to hearing loss. Weatherley et al. analyzed fundamental frequency measurements in 19 normal-hearing subjects and compared them with measurements in 21 subjects with hearing loss. The mean F0 value for these subjects  was 189.68 Hz for women with hearing loss; no difference was seen between subjects with hearing loss and normal-hearing subjects.20 An increased F0 in severe hearing loss may be explained by studies on auditory monitoring that report increased F0 values with reduced auditory monitoring.14 Subject in our study all had hearing loss, so it may be assumed that increased mean F0 values were due to decreased auditoryvoice monitoring.0 values were also correlated with audiometric configurations. 0 of sustained issuing of vowel “a”, the connected speech sample and audiometric configurations. We noted a statistically significant difference between the connected speech sample F0 and audiometric configurations. The mean F0value was low for the abrupt configuration (176.32 Hz) compared to the flat configuration (191.63 Hz), the gradual configuration (197.61 Hz) and the sloping configuration (189.85 HZ). The conclusion is that the F0 mean was higher in the gradually sloping audiometric configuration, in which there is a 5 to 12 dB difference in auditory thresholds between frequency octaves.FOur data suggest the auditory feedback regulates voice production by monitoring different voice parameters. In the elderly it is clear how hearing loss and voice changes are related. Hearing affects voice production by changing its parameters, especially in subjects with marked hearing loss. These indicators point to the need for early auditory rehabilitation and routine assessments of voice disorders in the elderly. Early auditory rehabilitation in elderly patients may help reduce voice changes, directly affecting communication and social interaction.0) of a sustained vowel was increased in marked low and high frequency hearing loss. The fundamental frequency (F0) of the connected speech sample was increased in the sloping audiometric configuration where marked loss was seen over 2 KHz.The fundamental frequency (F


To verify the accuracy of smartphone apps to identify hearing loss.A systematic review followed the PRISMA-DATA checklist. The search strategies were applied across four databases  and grey literature .The acronym PIRD was used in review. This included populations of any gender and all age groups. The Index test is the smartphone-based hearing screening test; the Reference test is the pure-tone audiometry, which is considered the gold reference for hearing diagnostics; the diagnosis was performed via validity data (sensitivity and specificity) to identify hearing loss and diagnostic studies.Two reviewers selected the studies in a two-step process. The risk of bias was assessed according to the criteria of the QUADAS-2.Of 1395 articles, 104 articles were eligible for full-text reading and 17 were included. Only four met all criteria for methodological quality. All of the included studies were published in English between 2015 and 2020. The applications Digits-in noise Test (5 articles), uHear (4 articles), HearScreen (2 articles), hearTest (2 articles) and Hearing Test (2 articles) were the most studied. All this application showed sensitivity and specificity values between 75 and 100%. The other applications were EarScale, uHearing Test, Free field hearing (FFH) and Free Hearing Test.uHear, Digit-in-Noise Test, HearTest and HearScreen have shown significant values of sensitivity and specificity and can be considered as the most accurate methods for screening of hearing impairment. There is also an estimation that 1.1 billion young people (aged 12-35 years) are at risk of hearing loss due to exposure to noise in recreational environments. Along with aging, this issue subsidizes part of the projections to increase the prevalence of hearing loss.It is estimated that 460 million people live with hearing impairment worldwide. Of these, 40.19 million are in Latin America and the Caribbean, with a projection of 87 million people in 2050Hearing impairment has functional, psychosocial, and economic impacts at different life stages, especially if not identified and treated. In children, these impacts are more evident in language development and their learning processes. In adults, it can severely limit work capacity, and in the elderly, it can generate psychosocial impacts that can worsen aging and social isolation.One of the main aspects of hearing loss health care is the prevention and identification of hearing loss using validated and accurate hearing screening instruments., access to hearing health services in remote-6 and/or applied automated hearing screening test with smarthphone or tablet at home without any specialised professionals.In the past few years, many methods for hearing screening have been developed in different countries, allowing individuals to perform the test with portable audiometric screening platforms with specialised professionals-10.Using smartphones as a resource for hearing screening has been broadly studied since there are approximately 5.1 billion smartphones worldwide, in both urban and rural areas, in addition to the increasing availability of online services. That makes hearing healthcare even more accessible to end-users and promotes the so-called mHealth, which is the use of information and communication technologies to provide and improve healthcare services,12.There are currently thousands of health-related apps, which are relatively new to the mobile health scene and assess hearing loss by using smartphone hardware and earphones. Some of these apps accurately measure auditory thresholds, such as uHear, EarTrumpet, and hearScreen. Their authors argue that these methods are key in environments with limited resources, where high-end audiometry equipment is not available-16.To be considered an accurate instrument, hearing screening tests must be quick, simple, low-cost and have high sensibility and specificity. Other features such as self-administered, automated and use signals and noise equivalent to daily-life situations can optimize the use of these tests in hearing screeningTherefore, it is crucial to evaluate existing smartphone app-based hearing screening methods and discover whether they are indeed accurate, that is, if they measure the proportion of actual positives that are correctly identified as having a hearing loss as well as the proportion of actual negatives that are correctly identified as not having any hearing loss.This systematic review aims to verify the accuracy of smartphone apps to identify hearing loss.Preferred Reporting Items for Systematic reviews and Meta-Analyses of Diagnostic Test Accuracy Studies (PRISMA-DTA) was prepared and registered on the Prospective Register of Systematic Reviews (PROSPERO) under registration No. CRD42019126378.A systematic review protocol based on the The question of this systematic review was “What is the accuracy of smartphone-based hearing screening tests for identifying hearing loss”?. It embraced studies from all languages, no filter is applied as to the language of the articles and no restriction regarding age, sex and nor time of publication. The search strategies are available in , was used to read titles and abstracts. Search date on all databases and grey literature was July 10th, 2018, the search was updated on December 2nd, 2019 and July 20nd, 2020.Electronic search strategies were developed for each of the following databases: Latin American and Caribbean Health Sciences (LILACS), PUBMED (including MedLine), SCOPUS, and Web of Science. The authors performed an additional search in the grey literature, including Google Scholar, OpenGrey and ProQuest Dissertations and Thesis as well as a manual search in reference lists of the included studies following the recommendations of Greenhalgh and PeacockP stands for population, I for index test, R for reference test, and D for diagnosis of interest. This review included populations of any gender and all age groups. The Index test is the smartphone-based hearing screening test; the Reference test is the pure-tone audiometry, which is considered the gold reference for hearing diagnostics; the diagnosis was performed via validity data (sensitivity and specificity) to identify hearing loss and diagnostic studies.The acronym PIRD is recommended for structuring the inclusion criteria that focuses on diagnosis study reviews. The authors included studies that relied on smartphone-based hearing screening tests to identify hearing loss to any degree and then compared their results to pure-tone audiometry, which is considered the reference standard for audiological evaluation.The authors excluded studies that met the following criteria: 1. Studies that did not use phone apps; 2. Studies that were not audiology-related; 3. Studies that did not compare screening methods of phone apps with the reference standard (audiometry); 4. Studies that did not show any validity measurements (sensitivity and specificity) or did not show sufficient data to calculate them; 5. Comments, letters, conference, summary, personal opinions, clinical trials, case-control and cohort studies; 6. Unavailable studies.Two independent reviewers evaluated and selected the articles to be included. In phase one, both reviewers read the titles and abstracts independently and applied the eligibility criteria. In phase two, the same two reviewers read the full text. Any disagreements between the two reviewers that persisted after applying the eligibility criteria were resolved through consensus with a third reviewer. The final selection was based on the reading of the full texts when each of the following items was identified: author, year and country, sample and age group, app/test type, test procedures, sensitivity, and specificity.. They assessed the risk of bias and applicability concerns in four main domains  and classified them as 'low', 'medium', or 'high'. Based on that information, the authors then used the Cochrane Collaboration's program Review Manager 5.3 to generate the figures.Two independent authors performed an article quality assessment based on the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2)The information collected from the studies was quantitative – sensitivity and specificity values, negative and positive predictive values, prevalence and accuracy – and qualitative – sample size, age group, test procedure analysis, pass-fail criterion, and type of stimulus used in the test. That is due to the fact that the answer to this review's problem requires a detailed analysis of the studies for the accuracy evidence of smartphone app-based hearing screenings.All studies were published in English in several countries in the last ten years.uHear-25, uHearing Test, EarScale, HearScreen,28, HearingTest,30, Digits-in-Noise Test,31-34, hearTest,36, Free Field Hearing (FFH), Free Hearing Test. The most investigated apps were Digits-in noise Test (5 articles) and uHear (4 articles).All of the studies included were published between 2015 and 2020. Nine apps were found: -30,35-37, except for Digits-in-Noise Test,31-34, which used speech stimulation through digits and Free field hearing (FFH) which used words.All apps found in this study used pure tone as the auditory stimulus, seven unclear articles in the 'index test' domain-29,35-37, three unclear article in the 'reference standard' domain,30,36, and two unclear articles in the 'flow and time' domain,27. Regarding the applicability of studies, three articles obtained a high risk of bias in the 'patient selection' domain,26,35 and one unclear article. Five studies showed a low risk of bias for all domains according to QUADAS-2: Barczik and Serpanos, Sousa et al.,34, Potgieter et al. and Szudek et al..The methodology of the selected studies was evaluated by using the Quality Assessment Tool for Diagnostic Precision Studies (QUADAS) with 14 items. Methodological limitations were identified in most of the included studies. One unclear articles in the 'patient selection' domainThe results for the quality assessment are summarised in The authors of this study extracted the absolute values of the hearing screening test and pure-tone audiometry test from the studies to perform the calculations so that positive and negative predictive values, prevalence, and accuracy could be established. Some studies did not present the absolute values that would allow calculations, so their authors were contacted. However, such information could not be obtained on time from seven studies.. The sensitivity of the selected studies varied substantially between good results , and excellent , while specificity varied between reasonable results  and excellent results . An exception was found in the study by Barczik & Serpanos, which performed a precision analysis according to three types of earphones and where a significant variability in the sensitivity and specificity values can be observed -25, HearScreen (2 articles),28, hearTest (2 articles),36 and Hearing Test (2 articles),30 were the most studied. The others applications were EarScale, uHearing Test, Free field hearing (FFH) and Free Hearing Test.The applications Digits-in-noise Test (5 articles).In general, it is consistent across all studies included in this systematic review that using quick and accessible methods for hearing screening is necessary for the current hearing healthcare situation. Hearing screening is a common approach used by professionals to raise public awareness and promote intervention,41.App-based hearing screening is accessible to the public, so it has become an instrument for health promotion. Studies suggest that it improves patients' adherence to treatment because it offers information on their condition, which allows them to question their treatment. Besides, they can store their results and check previous screenings, as well as access healthcare services for diagnosis applied such screening methods to individuals older than 18 years and concluded it was a reasonable test to dismiss moderate hearing loss.Based on that information and the results of this review, it is clear that the uHear app has been used as a research tool on this subject and has shown effectiveness for identifying more significant hearing losses since individuals with more considerable hearing losses tend to fail this screening. Szudek et al. used the uHear app with an elderly population and noticed that this screening method showed excellent sensibility (100%) and fair specificity (60%). Also, it proved to be a practical and useful screening tool for hearing loss in the elderly population since it is free to download and easy to use. Furthermore, this method is well accepted by the elderly and is also useful in dismissing significant hearing loss. However, the study emphasises the need for further research to determine an ideal cut-off point before it can be routinely used as a screening tool for geriatric oncology purposes.Abu-Ghanem et al.  along with the uHearingTest application, where the accuracy was verified according to the type of headset  and with the different pure tone frequencies. The authors concluded that earbuds showed better sensitivity and specificity values for uHear, and the supra-aural headphone proved to be more accurate for uHearingTest. The researchers emphasize how important it is to use applications in hearing screening exclusively with the appropriate transducers.UHear was also studied by Barczik and Serpanos used uHear in a small population with an extensive age range, including adult and elderly patients, and applied the test in different environments. They concluded that the sensitivity of the uHear app for iPhone is excellent (100% sensitive) to track disabling hearing loss and has better accuracy for high-frequency hearing loss in silent or acoustically-treated rooms than in waiting rooms, but showed variable specificity values (64–88%) according to the environment tested.On the other hand, Peer and Fagan. Louw et al. used the HearScreen app in primary care clinics in 1,236 individuals older than 16 years and concluded that the method is effective and can become a tool for early identification of hearing loss. Mahomed-Asmail et al. used the same app on more than 1,000 school-aged children and also concluded that it delivers a low-cost, accurate, and efficient screening solution at school.HearScreen is another app that has proven to be accurate. It has been used with a younger, school-aged population and is considered a cheap alternative to conventional audiometry without significant differences between the results of hearing screening tests and conventional audiometry.EarScale was yet another application used for hearing screening of 85 students. The app proved to be an accurate method to identify more significant hearing losses in that population, with sensitivity values between 95.2-100% and specificity of 100 used the Hearing Test screening tool in their study. It showed excellent sensitivity (98%) and good specificity (79%), confirming the potential application in hearing monitoring, screening tests, or epidemiological tests on a large scale. Durgut et al. used the Hearing Test compared to conventional audiometry to assess hearing thresholds in children with Otitis Media with Effusion (OME) and to determine the accuracy and reliability of this method. They concluded that there was no statistically significant correlation between the screening result by the application with the average of pure tone thresholds of conventional audiometry, since it presented a very low specificity value (26.4%) indicating that it is not an appropriate screening test for to detect hearing loss in children with OME.Masalski et al. studied this application, obtained high specificity and sensitivity values , concluding that it is an effective method for identifying hearing losses. However, a limitation related to differences in responses was discussed when the test is performed by the individual (self-test) and when there is a facilitator during its performance. Thinking about it, Corona et al. also investigated hearTest in these conditions and with a sample composed of children and adults and observed that sensitivity and specificity were> 90% to identify disabling hearing loss for both response modes (self-test) or facilitator with adults and children. They also found a similar sensitivity value in identifying any level of hearing loss for both response modes in children, with specificity> 80%, and for the self-test mode in adults. Low specificity was observed when identifying any level of hearing loss in adults using the facilitator test.The HearTest is based on the validated hearing screen technology. Sandström et al.In this systematic review, 11 of 17 included articles used pure tone stimuli. Only five articles used digits in noise, while one article used both pure tone and words as their stimuli on the smartphone. compared two hearing screening methods: The Free Field Hearing (FFH) program, which used speech stimulus (disyllabic list); and the Free Hearing Test app, which used pure tone. This study was the only that used speech stimulus (words). The Free Hearing Test app was more efficient than the FFH, and it can be particularly useful in places where pure-tone audiometry facilities are not available. The authors highlighted that speech stimuli are better to measure individuals' actual communicative function abilities-46. However, the use of words may have been influenced by factors such as the subjects' language skills, language fluency, or social and environmental aspects, for example.The study by Swami et al. state that it is essential to use familiar words in a closed set rather than open sentences to reduce the effects of pre-existing language skills difficulties on the test result. A prevalent category is digits as they belong to the most spoken words in any age group.Smits et al. used an app involving hearing screening through speech material (digits) with background noise called Digits-in-Noise Test. The app is essential to provide additional information on the impairment of speech recognition in noise and also has excellent sensitivity (88%) and specificity (88%) to identify auditory alterations. Using digits as a stimulus has been widely accepted by researchers since language fluency or social and environmental factors do not influence the output.The study by Potgieter et al. also verified the accuracy of Digits-in-Noise Test and the influence of factors such as age, the degree of hearing loss, and linguistic competence between South African English native and non-native speakers. They observed age and linguistic competence had a significant impact in identifying individuals with hearing loss and that it is an accurate method, with 94% sensitivity and 77% specificity. It is worth nothing that, although digits reduce the effects of language skills, there is still an influence of language on the test result, which requires further studies.Potgieter et al. studied the use of the Digit-in-Noise Test using digits that are phase inverted (antiphasic) between the ears, while leaving the masking noise interaurally in-phase. Such a configuration of stimuli was shown to improve of the Digit-In-Noise Test SRTs in normal hearing listeners. They started from the hypothesis that homophasic diotic or monoaural stimuli may not be sensitive to detect unilateral, asymmetric or conductive hearing losses. They concluded with this study that the use of this test with antiphasic stimuli proved to be more sensitive (85%) to detect unilateral and asymmetric and conductive hearing losses in relation to the presentation of homophasic diotic stimuli (83%), however it proved to be less specific in this case. correlation (60%).Souza et al. investigated whether the use of DIN Test is effective to detect this type of hearing loss and concluded that the use of the application combined with the research of pure tone thresholds by air has good precision and high sensitivity and specificity .Still on conductive hearing losses, Sousa et al. reported that an appropriate cutoff point for the DIN test to identify abnormal hearing would generally be in the range between 0 and signal-to-noise ratio of 5 decibels (dB SNR). Dawes et al. used the following cutoff points: <-5.5dB SNR for normal hearing performance, -5.5dB SNR to -3.5dB SNR for insufficient hearing performance, and> SNR of -3.5dB for auditory performance bad.There are no standard cutoff points for the DIN test. These cutoff points tend to vary according to the study. Koole et al. sought to establish cutoff points for the DIN test according to age and sex through a population-based study and obtained the following categories: SNR <-5.55dB , between -5.55 and - 3.80dB SNR (insufficient) and> -3.80dB SNR (poor). They did not find differences between age, sex and / or age and sex and that the DIN test showed high values of sensitivity and specificity to detect moderate hearing losses , agreeing with most studies that reveal their importance in identifying more significant hearing losses.Armstrong et al.In general, all studies included in this review provided important information to clarify which applications can be considered accurate for the identification of hearing loss. However, bias analysis showed that there is a need for more accurate information, such as describing the procedures for applying the tests and the reference standard, as well as a more substantial concern that such methods are replicated in other research.Based on all the results of this systematic review, all studies point to the need to test the application so that early detection of hearing loss is increasingly accessible to all changes, whether in urban or rural areas and all age groups.This systematic review investigated the accuracy of smartphone apps to identify hearing loss. One of the limitations of this study was the exclusion of many articles because their methodologies did not contain enough data to support precise values of accuracy, prevalence and predictive values. Another limitation was the lack of ability to perform a meta-analysis due to the heterogeneity of analysis requests between the index tests (applications) and the reference test (pure tone audiometry). In this regard, it was observed that some studies used the mean threshold reference test at 20, or 25 or 40 dB regardless of the age range of the investigated subjects. This difference in the criteria of the reference test can affect the outcomes related to accuracy, therefore it is a limitation of the study that made the meta-analysis unfeasible. New studies involving the accuracy of these applications on a large scale and in all age groups need to be carried out.uHear, Digit-in-Noise Test, HearTest and HearScreen have shown significant values of sensitivity and specificity and can be considered as the most accurate methods for screening of hearing impairment.