A Survey on the Affordances of “Hearables” <s> Electrophysiology <s> The terminology used in thermal physiology is examined, and principles of heat transfer are discussed, taking into account heat quantity, heat flux, temperature, pressure, quantities used in physiology, a number of common definitions, the equivalence between different forms of energy, the release of potential energy in living tissues, heat transfer without change of state, and heat transfer with change of state. Temperature and humidity measurement are considered along with man and his environment, the temperature distribution in the systems and tracts of the human body, physiological changes affecting the temperature distribution, problems of temperature regulation, questions of heat loss and conservation, acclimatization to heat and cold, and disorders of thermoregulation. Attention is given to possible thermal imaging applications, causes of temperature irregularities in the head and neck, common causes of increased temperatures of upper limbs, and thermography in disease. 193 references. <s> BIB001 </s> A Survey on the Affordances of “Hearables” <s> Electrophysiology <s> Abstract It is widely accepted in the brain computer interface (BCI) research community that neurological phenomena are the only source of control in any BCI system. Artifacts are undesirable signals that can interfere with neurological phenomena. They may change the characteristics of neurological phenomena or even be mistakenly used as the source of control in BCI systems. Electrooculography (EOG) and electromyography (EMG) artifacts are considered among the most important sources of physiological artifacts in BCI systems. Currently, however, there is no comprehensive review of EMG and EOG artifacts in BCI literature. This paper reviews EOG and EMG artifacts associated with BCI systems and the current methods for dealing with them. More than 250 refereed journal and conference papers are reviewed and categorized based on the type of neurological phenomenon used and the methods employed for handling EOG and EMG artifacts. This study reveals weaknesses in BCI studies related to reporting the methods of handling EMG and EOG artifacts. Most BCI papers do not report whether or not they have considered the presence of EMG and EOG artifacts in the brain signals. Only a small percentage of BCI papers report automated methods for rejection or removal of artifacts in their systems. As the lack of dealing with artifacts may result in the deterioration of the performance of a particular BCI system during practical applications, it is necessary to develop automatic methods to handle artifacts or to design BCI systems whose performance is robust to the presence of artifacts. <s> BIB002 </s> A Survey on the Affordances of “Hearables” <s> Electrophysiology <s> Hybrid Brain-Computer Interfaces (BCI) are representing a recent approach to develop practical BCIs. In such a system disabled users are able to use all their remaining functionalities as control possibilities in parallel with the BCI. Sometimes these people have residual activity of their muscles. Therefore, in the presented hybrid BCI framework we want to explore the parallel usage of electroencephalographic (EEG) and electromyographic (EMG) activity, whereby the control abilities of both channels are fused. Results showed that the participants could achieve a good control of their hybrid BCI independently of their level of muscular fatigue. Thereby the multimodal fusion approach of muscular and brain activity yielded better and more stable performance compared to the single conditions. Even in the case of an increasing muscular fatigue a good control (moderate and graceful degradation of the performance compared to the non-fatigued case) and a smooth handover could be achieved. Therefore, such systems allow the users a very reliable hybrid BCI control although they are getting more and more exhausted or fatigued during the day. <s> BIB003 </s> A Survey on the Affordances of “Hearables” <s> Electrophysiology <s> An algorithmic framework is proposed to process acceleration and surface electromyographic (SEMG) signals for gesture recognition. It includes a novel segmentation scheme, a score-based sensor fusion scheme, and two new features. A Bayes linear classifier and an improved dynamic time-warping algorithm are utilized in the framework. In addition, a prototype system, including a wearable gesture sensing device (embedded with a three-axis accelerometer and four SEMG sensors) and an application program with the proposed algorithmic framework for a mobile phone, is developed to realize gesture-based real-time interaction. With the device worn on the forearm, the user is able to manipulate a mobile phone using 19 predefined gestures or even personalized ones. Results suggest that the developed prototype responded to each gesture instruction within 300 ms on the mobile phone, with the average accuracy of 95.0% in user-dependent testing and 89.6% in user-independent testing. Such performance during the interaction testing, along with positive user experience questionnaire feedback, demonstrates the utility of the framework. <s> BIB004 </s> A Survey on the Affordances of “Hearables” <s> Electrophysiology <s> This study presents first evidence that reliable EEG data can be recorded with a new cEEGrid electrode array, which consists of ten electrodes printed on flexible sheet and arranged in a c-shape to fit around the ear. Ten participants wore two cEEGrid systems for at least seven hours. Using a smartphone for stimulus delivery and signal acquisition, resting EEG and auditory oddball data were collected in the morning and in the afternoon six to seven hours apart. Analysis of resting EEG data confirmed well-known spectral differences between eyes open and eyes closed conditions. The ERP results confirmed the predicted condition effects with significantly larger P300 amplitudes for target compared to standard tones, and a high test-retest reliability of the P300 amplitude (r > = .74). Moreover, a linear classifier trained on data from the morning session revealed similar performance in classification accuracy for the morning and the afternoon sessions (both > 70%). These findings demonstrate the feasibility of concealed and comfortable brain activity acquisition over many hours. <s> BIB005 </s> A Survey on the Affordances of “Hearables” <s> Electrophysiology <s> We introduce a novel in-ear sensor which satisfies key design requirements for wearable electroencephalography (EEG)—it is discreet, unobtrusive, and capable of capturing high-quality brain activity from the ear canal. Unlike our initial designs, which utilize custom earpieces and require a costly and time-consuming manufacturing process, we here introduce the generic earpieces to make ear-EEG suitable for immediate and widespread use. Our approach represents a departure from silicone earmoulds to provide a sensor based on a viscoelastic substrate and conductive cloth electrodes, both of which are shown to possess a number of desirable mechanical and electrical properties. Owing to its viscoelastic nature, such an earpiece exhibits good conformance to the shape of the ear canal, thus providing stable electrode–skin interface, while cloth electrodes require only saline solution to establish low impedance contact. The analysis highlights the distinguishing advantages compared with the current state-of-the-art in ear-EEG. We demonstrate that such a device can be readily used for the measurement of various EEG responses. <s> BIB006 </s> A Survey on the Affordances of “Hearables” <s> Electrophysiology <s> Bioelectrical signals representing electrical activities of human brain, eyes, and facial muscles have found widespread use both as important inputs for critical medical issues and as an invisible communication pathway between human and external devices. However, existing techniques for measuring those biosignals require attaching electrodes on the face and do not come in handy sizes for daily usage. Additionally, no study has been capable of providing all three biosignals with high fidelity simultaneously. In this paper, we present a low-cost bioelectrical sensing system, called LIBS, that can robustly collect the biosignal of good quality from inside human ears and extract all those three fundamental biosignals without loss of information. The practicality of LIBS is shown through one real world scenario of a sleep quality monitoring system. Based on preliminary results, we further propose potential healthcare applications utilizing the sensor's outputs for our future research. <s> BIB007 </s> A Survey on the Affordances of “Hearables” <s> Electrophysiology <s> Future health systems require the means to assess and track the neural and physiological function of a user over long periods of time, and in the community. Human body responses are manifested through multiple, interacting modalities – the mechanical, electrical and chemical; yet, current physiological monitors (e.g. actigraphy, heart rate) largely lack in cross-modal ability, are inconvenient and/or stigmatizing. We address these challenges through an inconspicuous earpiece, which benefits from the relatively stable position of the ear canal with respect to vital organs. Equipped with miniature multimodal sensors, it robustly measures the brain, cardiac and respiratory functions. Comprehensive experiments validate each modality within the proposed earpiece, while its potential in wearable health monitoring is illustrated through case studies spanning these three functions. We further demonstrate how combining data from multiple sensors within such an integrated wearable device improves both the accuracy of measurements and the ability to deal with artifacts in real-world scenarios. <s> BIB008
There are several types of bio signals that are obtained from differential electrophysiology, including signals pertaining to brain state (EEG) muscle activity (EMG), and eye activity (EOG), amongst others. The apparatuses for collecting these signals involve a minimum of three continuous measurements, a ground reference, as well as a positive and a negative signal. Remarkably, research has demonstrated that not only can differential electrophysiology measurements be obtained from the ear canal BIB006 , but that simple single channel measurements can potentially be decomposed to reveal multiple underlying signal types BIB007 . While there are vast amounts of literature on electroencephalography (EEG) recordings, here we focus on only a few affordances that might be gained from relatively small ear-mounted systems. Existing systems have been designed to collect EEG data from around BIB005 or within the ear BIB006 . EEG data has already been used within Brain-Computer Interfaces (BCI) for years in a number of applications like wheelchair control, Augmentative and Alternative Communication (AAC) systems, drive-by-wire automobiles, etc. It remains to be seen if the relatively simple EEG measurements obtained from hearables will be capable of serving in similar applications. While many of these systems have been focused on applications for the disabled, able-bodied persons will also be able to benefit from similar applications  . Further, single channel EEG measurements can also be used to monitor a user's general sleep patterns BIB008 . Electromyography (EMG) captures electrical signals stemming from muscle activity, and ear-mounted systems can not only record ear muscle gestures (such as an ear wiggle), but also jaw, mouth, nose, and eyebrow gestures  . EMG has recently been implemented as a computer control device in non-ear mounted solutions, such as EMG bracelets BIB004 . One of the real affordances of EMG signals is the ability to associate the contraction of certain muscles with various computer control  , such as flexing the wrist upwards in order to turn on one's mobile device. Within hearables, EMG signals could likewise be used to trigger various computer functions, or silently respond to computer generated prompts. EMG data and EEG data, while both noisy, have been successfully combined in multi-modal systems in order to improve the accuracy of BCIs BIB004 BIB003 . In addition to EEG and EMG recordings, differential electrophysiology can be also used to track eye-blinks via electrooculography (EOG). The affordances of EOG measurements are similar to the other differential bio signals: namely, the ability to trigger an event with bodily gestures (such as eye blinks, or a series of eye blinks in quick succession). EOG measurements are also used to remove eye-blink artifacts from other electrophysiological data BIB002 . Electrodermal activity, a measure of the skin's conduciveness, is a similar, yet unique electrophysiological signal that has not, to our knowledge, been exploited in hearables. While true that the insides of the ear do not sweat  , the outside or back of the ear offer a potential location to measure EDA. As opposed to more common locations such as the fingers or wrist, the ears are an area of the body that stays roughly at the same temperature BIB001 . Unlike differential electrophysiological measurements that require three electrodes, EDA measurements only require two electrodes. The affordance of adding EDA sensors to a hearable would be the ability to collect long-term information pertaining to the arousal level of the user; a feature that has been associated with fear, anger, startled response, orienting response, and sexual feelings [43] .