A Survey of auditory display in image-guided interventions <s> Discussion <s> This paper presents an experimental study of the effects of individual sound parameters on perceived (psychoacoustic) urgency. Experimental Series 1 showed that fundamental frequency, harmonic series, amplitude envelope shape, and delayed harmonics all have clear and consistent effects on perceived urgency. Experimental Series 2 showed that temporal and melodic parameters such as speed, rhythm, pitch range, and melodic structure also have clear and consistent effects on perceived urgency. The final experiment tested a set of 13 auditory warnings generated by an application of the earlier experimental findings. The urgency rank ordering of this warning set was predicted, and the correlation between the predicted and the obtained order was highly significant. The results of these experiments have a widespread application in the improvement of existing auditory warning systems and the design of new systems, where the psychoacoustic and psychological appropriateness of warnings could be enhanced. <s> BIB001 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> Current medical visualization technology intended for positional guidance in surgical applications may only ever have limited utility in the operating room due to the preexisting visual requirements of surgical practice. Additionally, visual systems impose limits as a result of their high latency, poor image resolution, problems with stereopsis and physical strain upon the user. Audio technology is relatively unexamined in the broad range of available methodologies for medical devices. The potential to translate surgical instrument position into audio feedback presents a novel solution to the human factors and engineering problems faced by visual display technology because audio technology employs a rich and as yet unburdened sensory modality. We describe an experimental system we have developed for investigating this new interface design approach using commercially available hardware. <s> BIB002 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> PURPOSE ::: To examine the perceived urgency of 13 auditory warning alarms commonly occurring in the hospital operating room. ::: ::: ::: METHODS ::: Undergraduate students, who were naïve with respect to the clinical situation associated with the alarms, judged perceived urgency of each alarm on a ten-point scale. ::: ::: ::: RESULTS ::: The perceived urgency of the alarms was not consistent with the actual urgency of the clinical situation that triggers it. In addition, those alarms indicating patient condition were generally perceived as less urgent than those alarms indicating the operation of equipment. Of particular interest were three sets of alarms designed by equipment manufacturers to indicate specific priorities for action. Listeners did not perceive any differences in the urgency of the 'information only', 'medium' and 'high' priority alarms of two of the monitors with all judged as low to moderate in urgency. In contrast, the high priority alarm of the third monitor was judged as significantly more urgent than its low and medium urgency counterparts. ::: ::: ::: CONCLUSION ::: The alarms currently in use do not convey the intended sense of urgency to naïve listeners, and this holds even for two sets of alarms designed specifically by manufacturers to convey different levels of urgency. <s> BIB003 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> BACKGROUND ::: Noise in operating rooms has been found to be much higher than the recommended level of 45 dB. The aim of this study was to objectively evaluate the effect of noise and music on the performance of a complex surgical task. ::: ::: ::: METHODS ::: Twelve surgeons with varying experience in laparoscopic suturing undertook 3 sutures in a laparoscopic trainer under 3 conditions: quiet, noise at 80 to 85 dB, and music. Other than the test conditions, all other conditions were standardized. A validated motion analysis system was used to assess performance. The tasks were recorded by video and played back to 2 blinded observers who rated the surgeons' performance on a global rating scale by observing the tasks for accuracy, knot quality, and number of nonpurposeful movements. ::: ::: ::: RESULTS ::: Time taken for the tasks (P=.78), total number of movements (P=.78), total path length (P=.47), global score (P=.54), accuracy, and knot quality remained unchanged across the 3 conditions. The main study measures had a high test-retest reliability and internal consistency. No learning effect was seen across the 3 conditions. ::: ::: ::: CONCLUSIONS ::: Surgeons can effectively "block out" noise and music. This is probably due to the high levels of concentration required for the performance of a complex surgical task. Future research should focus on the effect of these conditions on communication in the operating room. <s> BIB004 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> OBJECTIVES ::: Direct haptic (force or tactile) feedback is not yet available in commercial robotic surgical systems. Previous work by our group and others suggests that haptic feedback might significantly enhance the execution of surgical tasks requiring fine suture manipulation, specifically those encountered in cardiothoracic surgery. We studied the effects of substituting direct haptic feedback with visual and auditory cues to provide the operating surgeon with a representation of the forces he or she is applying with robotic telemanipulators. ::: ::: ::: METHODS ::: Using the robotic da Vinci surgical system (Intuitive Surgical, Inc, Sunnyvale, Calif), we compared applied forces during a standardized surgical knot-tying task under 4 different sensory-substitution scenarios: no feedback, auditory feedback, visual feedback, and combined auditory-visual feedback. ::: ::: ::: RESULTS ::: The forces applied with these sensory-substitution modes more closely approximate suture tensions achieved under ideal haptic conditions (ie, hand ties) than forces applied without such sensory feedback. The consistency of applied forces during robot-assisted suture tying aided by visual feedback or combined auditory-visual feedback sensory substitution is superior to that achieved with hand ties. Robot-assisted ties aided with auditory feedback revealed levels of consistency that were generally equivalent or superior to those attained with hand ties. Visual feedback and auditory feedback improve the consistency of robotically applied forces. ::: ::: ::: CONCLUSIONS ::: Sensory substitution, in the form of visual feedback, auditory feedback, or both, confers quantifiable advantages in applied force accuracy and consistency during the performance of a simple surgical task. <s> BIB005 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> Image-guided interventions are medical procedures that use computer-based systems to provide virtual image overlays to help the physician precisely visualize and target the surgical site. This field has been greatly expanded by the advances in medical imaging and computing power over the past 20 years. This review begins with a historical overview and then describes the component technologies of tracking, registration, visualization, and software. Clinical applications in neurosurgery, orthopedics, and the cardiac and thoracoabdominal areas are discussed, together with a description of an evolving technology named Natural Orifice Transluminal Endoscopic Surgery (NOTES). As the trend toward minimally invasive procedures continues, image-guided interventions will play an important role in enabling new procedures, while improving the accuracy and success of existing approaches. Despite this promise, the role of image-guided systems must be validated by clinical trials facilitated by partnerships between scie... <s> BIB006 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> Background and Objective: The purpose of the study was to evaluate the perception of influence of music among surgeons, anesthesiologist and nurses in our hospital as well as to critically evaluate whether music can be used as an aid in improving the work efficiency of medical personnel in the operation theatre (OT). Materials and Methods: A prospective, questionnaire-based cross-sectional study was conducted. A total of 100 randomly selected subjects were interviewed, which included 44 surgeons, 25 anesthesiologists and 31 nurses. Statistical package for social sciences (SPSS) Windows Version 16 software was used for statistical evaluation. Results: Most of the OT medical personnel were found to be aware of the beneficial effects of music, with 87% consenting to the playing of music in the OT. It was also found that most participants agreed to have heard music on a regular basis in the OT, while 17% had heard it whenever they have been to the OT. Conclusions: Majority of the respondent's preferred playing music in the OT which helped them relax. It improved the cognitive function of the listeners and created a sense of well being among the people and elevated mood in them. Music helped in reducing the autonomic reactivity of theatre personnel in stressful surgeries allowing them to approach their surgeries in a more thoughtful and relaxed manner. Qualitative, objective and comprehensive effect of specific music types varied with different individuals. Music can aid in improving the work efficiency of medical personnel in the OT. The study has reinforced the beneficial effects of playing music in the OT outweighing its deleterious outcomes. <s> BIB007 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> Purpose We developed a surgical navigation system that warns the surgeon with auditory and visual feedback to protect the facial nerve with real-time monitoring of the safe region during drilling. <s> BIB008 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> BACKGROUND ::: A neuronavigation interface with extended function as compared with current systems was developed to aid during temporal bone surgery. The interface, named EVADE, updates the prior anatomical image and visualizes the bone drilling process virtually in real-time without need for intra-operative imaging. Furthermore, EVADE continuously calculates the distance from the drill tip to segmented temporal bone critical structures (e.g. the sigmoid sinus and facial nerve) and produces audiovisual warnings if the surgeon drills in too close vicinity. The aim of this study was to evaluate the accuracy and surgical utility of EVADE in physical phantoms. ::: ::: ::: METHODOLOGY/PRINCIPAL FINDINGS ::: We performed 228 measurements assessing the position accuracy of tracking a navigated drill in the operating theatre. A mean target registration error of 1.33±0.61 mm with a maximum error of 3.04 mm was found. Five neurosurgeons each drilled two temporal bone phantoms, once using EVADE, and once using a standard neuronavigation interface. While using standard neuronavigation the surgeons damaged three modeled temporal bone critical structures. No structure was hit by surgeons utilizing EVADE. Surgeons felt better orientated and thought they had improved tumor exposure with EVADE. Furthermore, we compared the distances between surface meshes of the virtual drill cavities created by EVADE to actual drill cavities: average maximum errors of 2.54±0.49 mm and -2.70±0.48 mm were found. ::: ::: ::: CONCLUSIONS/SIGNIFICANCE ::: These results demonstrate that EVADE gives accurate feedback which reduces risks of harming modeled critical structures compared to a standard neuronavigation interface during temporal bone phantom drilling. <s> BIB009 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> Background ::: ::: An alternative mode of interaction with navigation systems for open liver surgery was requested. Surgeons who use such systems are impeded by having to constantly switch between viewing the navigation system screen and the patient during an operation. ::: ::: ::: ::: Methods ::: ::: To this end, an auditory display system for open liver surgery is introduced with support for guiding the tracked instrument towards and remaining on a predefined resection line. To evaluate the method, a clinically orientated user study with 12 surgeons was conducted. ::: ::: ::: ::: Results ::: ::: It is shown in qualitative results from the user study that the proposed auditory display is recognized as a useful addition to the current visual mode of interaction. It was revealed in a statistical analysis that participants spent less time looking on the screen (10% vs. 96%). Accuracy for resection guidance was significantly improved when using auditory display as an additional information channel (0.6 vs. 1.4 mm); however, the overall time for the resection task was shorter without auditory display (47 vs. 24 s). ::: ::: ::: ::: Conclusions ::: ::: By reducing dependence on the visual modality during resection guidance, the auditory display is well suited to become integrated in navigation systems for liver surgery. Copyright © 2012 John Wiley & Sons, Ltd. <s> BIB010 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> OBJECTIVES/HYPOTHESIS ::: Image-guided surgery (IGS) systems are frequently utilized during cranial base surgery to aid in orientation and facilitate targeted surgery. We wished to assess the performance of our recently developed localized intraoperative virtual endoscopy (LIVE)-IGS prototype in a preclinical setting prior to deployment in the operating room. This system combines real-time ablative instrument tracking, critical structure proximity alerts, three-dimensional virtual endoscopic views, and intraoperative cone-beam computed tomographic image updates. ::: ::: ::: STUDY DESIGN ::: Randomized-controlled trial plus qualitative analysis. ::: ::: ::: METHODS ::: Skull base procedures were performed on 14 cadaver specimens by seven fellowship-trained skull base surgeons. Each subject performed two endoscopic transclival approaches; one with LIVE-IGS and one using a conventional IGS system in random order. National Aeronautics and Space Administration Task Load Index (NASA-TLX) scores were documented for each dissection, and a semistructured interview was recorded for qualitative assessment. ::: ::: ::: RESULTS ::: The NASA-TLX scores for mental demand, effort, and frustration were significantly reduced with the LIVE-IGS system in comparison to conventional navigation (P < .05). The system interface was judged to be intuitive and most useful when there was a combination of high spatial demand, reduced or absent surface landmarks, and proximity to critical structures. The development of auditory icons for proximity alerts during the trial better informed the surgeon while limiting distraction. ::: ::: ::: CONCLUSIONS ::: The LIVE-IGS system provided accurate, intuitive, and dynamic feedback to the operating surgeon. Further refinements to proximity alerts and visualization settings will enhance orientation while limiting distraction. The system is currently being deployed in a prospective clinical trial in skull base surgery. <s> BIB011 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> Mechanics-based models of concentric tube continuum robots have recently achieved a level of sophistication that makes it possible to begin to apply these robots to a variety of real-world clinical scenarios. Endonasal skull base surgery is one such application, where their small diameter and tentacle like dexterity are particularly advantageous. In this paper we provide the medical motivation for an endonasal surgical robot featuring concentric tube manipulators, and describe our model-based design and teleoperation methods, as well as a complete system incorporating image-guidance. Experimental demonstrations using a laparoscopic training task, a cadaver reachability study, and a phantom tumor resection experiment illustrate that both novice and expert users can effectively teleoperate the system, and that skull base surgeons can use the robot to achieve their objectives in a realistic surgical scenario. <s> BIB012 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> Image-guided medical interventions more frequently rely on Augmented Reality (AR) visualization to enable surgical navigation. Current systems use 2-D monitors to present the view from external cameras, which does not provide an ideal perception of the 3-D position of the region of interest. Despite this problem, most research targets the direct overlay of diagnostic imaging data, and only few studies attempt to improve the perception of occluded structures in external camera views. The focus of this paper lies on improving the 3-D perception of an augmented external camera view by combining both auditory and visual stimuli in a dynamic multi-sensory AR environment for medical applications. Our approach is based on Temporal Distance Coding (TDC) and an active surgical tool to interact with occluded virtual objects of interest in the scene in order to gain an improved perception of their 3-D location. Users performed a simulated needle biopsy by targeting virtual lesions rendered inside a patient phantom. Experimental results demonstrate that our TDC-based visualization technique significantly improves the localization accuracy, while the addition of auditory feedback results in increased intuitiveness and faster completion of the task. <s> BIB013 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> This article deals with the process of sonification design for guidance tasks. It presents several studies that aim at overcoming two major problems of sonification: the aesthetics of sound design and the lack of a general method. On the basis of these studies, it proposes some guidelines for the generalization of the sonification process. First, it introduces the need to disassociate data and display dimensions; then, it proposes a method to classify and evaluate sound strategies; finally, it introduces a method for the customization of the sound design. The whole process is based on the identification and the manipulation of particular sound morphologies. <s> BIB014 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> IMPORTANCE ::: Previous preclinical studies of localized intraoperative virtual endoscopy-image-guided surgery (LIVE-IGS) for skull base surgery suggest a potential clinical benefit. ::: ::: ::: OBJECTIVE ::: The first aim was to evaluate the registration accuracy of virtual endoscopy based on high-resolution magnetic resonance imaging under clinical conditions. The second aim was to implement and assess real-time proximity alerts for critical structures during skull base drilling. ::: ::: ::: DESIGN AND SETTING ::: Patients consecutively referred for sinus and skull base surgery were enrolled in this prospective case series. ::: ::: ::: PARTICIPANTS ::: Five patients were used to check registration accuracy and feasibility with the subsequent 11 patients being treated under LIVE-IGS conditions with presentation to the operating surgeon (phase 2). ::: ::: ::: INTERVENTION ::: Sixteen skull base patients were endoscopically operated on by using image-based navigation while LIVE-IGS was tested in a clinical setting. ::: ::: ::: MAIN OUTCOME AND MEASURES ::: Workload was quantitatively assessed using the validated National Aeronautics and Space Administration Task Load Index (NASA-TLX) questionnaire. ::: ::: ::: RESULTS ::: Real-time localization of the surgical drill was accurate to ~1 to 2 mm in all cases. The use of 3-mm proximity alert zones around the carotid arteries and optic nerve found regular clinical use, as the median minimum distance between the tracked drill and these structures was 1 mm (0.2-3.1 mm) and 0.6 mm (0.2-2.5 mm), respectively. No statistical differences were found in the NASA-TLX indicators for this experienced surgical cohort. ::: ::: ::: CONCLUSIONS AND RELEVANCE ::: Real-time proximity alerts with virtual endoscopic guidance was sufficiently accurate under clinical conditions. Further clinical evaluation is required to evaluate the potential surgical benefits, particularly for less experienced surgeons or for teaching purposes. <s> BIB015 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> BACKGROUND ::: Minimally invasive biopsies, drainages and therapies in the soft tissue organs of the thorax and abdomen are typically performed through a needle, which is inserted percutaneously to reach the target area. The conventional workflow for needle placement employs an iterative freehand technique. This article provides an overview of needle-placement systems developed to improve this method. ::: ::: ::: METHODS ::: An overview of systems for needle placement was assembled, including those found in scientific publications and patents, as well as those that are commercially available. The systems are categorized by function and tabulated. ::: ::: ::: RESULTS ::: Over 40 systems were identified, ranging from simple passive aids to fully actuated robots. ::: ::: ::: CONCLUSIONS ::: The overview shows a wide variety of developed systems with growing complexity. However, given that only a few systems have reached commercial availability, it is clear that the technical community is struggling to develop solutions that are adopted clinically. Copyright © 2014 John Wiley & Sons, Ltd. <s> BIB016 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> This article aims to reveal the efficiency of sonification strategies in terms of rapidity, precision and overshooting in the case of a one-dimensional guidance task. The sonification strategies are based on the four main perceptual attributes of a sound (i.e. pitch, loudness, duration/tempo and timbre) and classified with respect to the presence or not of one or several auditory references. Perceptual evaluations are used to display the strategies in a precision/rapidity space and enable prediction of user behavior for a chosen sonification strategy. The evaluation of sonification strategies constitutes a first step toward general guidelines for sound design in interactive multimedia systems that involve guidance issues. <s> BIB017 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> BACKGROUND ::: Image-guided systems have recently been introduced for their application in liver surgery. We aimed to identify and propose suitable indications for image-guided navigation systems in the domain of open oncologic liver surgery and, more specifically, in the setting of liver resection with and without microwave ablation. ::: ::: ::: METHOD ::: Retrospective analysis was conducted in patients undergoing liver resection with and without microwave ablation using an intraoperative image-guided stereotactic system during three stages of technological development (accuracy: 8.4 ± 4.4 mm in phase I and 8.4 ± 6.5 mm in phase II versus 4.5 ± 3.6 mm in phase III). It was evaluated, in which indications image-guided surgery was used according to the different stages of technical development. ::: ::: ::: RESULTS ::: Between 2009 and 2013, 65 patients underwent image-guided surgical treatment, resection alone (n = 38), ablation alone (n = 11), or a combination thereof (n = 16). With increasing accuracy of the system, image guidance was progressively used for atypical resections and combined microwave ablation and resection instead of formal liver resection (p < 0.0001). ::: ::: ::: CONCLUSION ::: Clinical application of image guidance is feasible, while its efficacy is subject to accuracy. The concept of image guidance has been shown to be increasingly efficient for selected indications in liver surgery. While accuracy of available technology is increasing pertaining to technological advancements, more and more previously untreatable scenarios such as multiple small, bilobar lesions and so-called vanishing lesions come within reach. <s> BIB018 </s> A Survey of auditory display in image-guided interventions <s> Discussion <s> Purpose ::: During medical needle placement using image-guided navigation systems, the clinician must concentrate on a screen. To reduce the clinician’s visual reliance on the screen, this work proposes an auditory feedback method as a stand-alone method or to support visual feedback for placing the navigated medical instrument, in this case a needle. <s> BIB019
This review presents, to the authors' knowledge, the first overview of the state of the art of auditory display for imageguided interventions. The articles included in the review cover a range of interventional tasks to be supported, auditory display methods, and evaluation designs and findings. Whereas a majority of the literature covers the use of auditory display to inform the clinician of risk structures, thereby prompting the clinician to navigate away from a certain object of interest, a number of articles attempt to aid clinicians in navigation toward a target itself. The body of results of the reviewed literature show that in most cases, systems with auditory display were found to be beneficial. Advantages include improved recognition of the presence of or distance to anatomical risk structures BIB008  BIB009 , reduced complication rate  , improved placement accuracy BIB010 BIB013 BIB019  , improved resection volume similarity  , improved orientation BIB009 , reduced workload demands BIB011 . Reported drawbacks included increased task time BIB010 BIB019  , increased workload BIB019 , and increased amount of non-target tissue removed during volumetric resection  . Considering the wide range of tasks that are currently supported with image guidance BIB006 and primarily positive evaluation results of the use of auditory display in the reviewed literature, it is surprising that only a limited amount of investigations have attempted tackling auditory display. Even when auditory display has been integrated into support for image guidance, the majority of attempts usually only implement a simple threshold-based alert. The paucity of investigations into more complex navigational aids might be traced to an unfamiliarity with the relatively nascent field of auditory display and its possibilities in enhancing guidance tasks, possibly prompted by clinician dissatisfaction with previous experiences with alarms. The abundance of other sounds in the operating environment, including speech and instrument noises, plays a role in the distrust or rejection of new auditory displays. This is discussed in the reviewed literature: An editorial comment in response to Willems et al.  recognizes the benefit of reducing the necessity of viewing a navigation screen, but is pessimistic of its clinical application: We doubt whether we would like to have such an auditory warning system in the operating room creating distracting sounds. Especially when surgery comes to critical areas, a beeping neuronavigation system may be annoying, since the operating room is already filled with acoustic warning systems of the anesthesiologist, with which an additional system should also not interfere. We should seek ways to increase the comfort for the surgeon in the operating room, allowing concentration on the surgical field, supported by enhanced guidance systems using modern 3-D visualizing techniques. This sentiment is reflected in statements by authors of the reviewed literature, who caution that auditory display methods should take the sounds in the existing operating room into account during the design phase to reduce annoyance or overburden the environment BIB010  BIB013 BIB008 BIB011 BIB005 BIB002 . To be sure, the operating room is a noisy environment, with average sound levels considerably higher than those of other workplaces [30] . However, according to Katz et al., "there is little evidence to demonstrate a direct association between excessive operating room noise and poor surgical outcomes." Music in the operating room has become commonplace [30] , and surgeon-selected music in the operating room has been reported to enhance performance  and reduce workload BIB007 . In addition, Moorthy et al. BIB004 report that surgeons can effectively block out unwanted noise in the operating room. As a whole, the effect of noise and music in the operating room is complex and not widely investigated, bringing into question any sweeping pessimism of the inclusion of auditory display for image guidance. Unfortunately, clinicians may associate novel auditory display methods with just another alarm. The perception that auditory displays equal alarms could be due to the lack of clinicians' experience with beneficial auditory displays, but also to approaches that amount to little more than simple alarms applied to an image guidance task. Parseihan et al. BIB014 note a major problem of designing auditory display for guidance tasks: the aesthetics of resulting sound design. The authors cite the discomfort caused by using auditory display designs; they can become fatiguing to use or do not match the listening tastes of the intended user. Indeed, the relationship between the intended urgency of a situation and the urgency perceived when using an auditory display is an important issue that should be considered during design BIB001 . Common auditory warnings in the operating room have been found to be inappropriate, conveying an unintended level of urgency BIB003 . Thus, clinicians' dissatisfaction with inappropriately urgent alarms may be one reason that investigations into potentially useful auditory display for image guidance never properly develop. Many of the reviewed approaches are indeed simple in nature, and most articles do not cite psychoacoustically or psychologically driven motivations for sound design decisions, prompting the assumption that most investigations tend to lack interdisciplinary collaboration between researchers of image guidance systems and researchers in field of auditory display. Bringing auditory display for image guidance into the operating room to provide usable and flexible support for clinicians demands fundamental changes. Enhanced cooperation with sound designers and experts in auditory display to produce more aesthetically appropriate auditory displays will encourage contextual inquiry to help limit implementation in cases when it is disadvantageous, and help discover new applications which might benefit from auditory display. Increasing sound design complexity so that auditory displays sound more like instruments and less like alarms could increase acceptance BIB010 and help differentiate the perception of displays from pure alarms that exist in the already noisy environment. Sound designs that are customizable based on clinicians' desires are also an interesting option to increase acceptance BIB010 BIB014 . Future development should carefully implement toggling so that sound output is only produced when absolutely necessary, a suggestion also offered by Dixon et al. BIB011 . This will further reduce unnecessary sound output and its related annoyance. More thorough evaluations of developed methods will help discern exactly which aspects of auditory display are most useful in the operating room and which are superfluous or better supported by other means. In addition to comparing the effects of auditory display to other intraoperative modalities such as augmented reality BIB015 , virtual reality, and conventional navigation, evaluations should include comparisons of multiple auditory display methods, which none of the reviewed literature provided. Investigations into comparing multiple methods for auditory display for one-dimensional guidance tasks suggest expanding such evaluations to 2-D and 3-D tasks BIB017 . Such an approach could be taken within the context of multidimensional tracked instrument placement, for instance, for needles BIB016 BIB018 , aspirators, or continuum robots BIB012 .