Evidence of Vestibular and Balance Dysfunction in Patients With Mild Cognitive Impairment and Alzheimer's Disease.

OBJECTIVES: Given the expected rise in dementia prevalence, early diagnosis is vital. As a growing body of literature has identified a potential association between vestibular function and cognition, vestibular assessment may aid in early screening. The aim of the study was to better comprehend the proposed association between vestibular function and Alzheimer's disease (AD) by comparing vestibular parameters (vestibular function testing and clinical balance measures) between a group with mild cognitive impairment (MCI), AD, and healthy controls with age-normal cognition. DESIGN: Cross-sectional analysis of the GECkO study, an ongoing prospective single-center longitudinal cohort study. This study included 100 older adults (55 to 84 years). A total of 33 participants with MCI, 17 participants with AD, and 50 participants of age, sex, and hearing-matched healthy controls were included. RESULTS: Participants with AD demonstrated a delayed latency of the p13 component measured by cervical vestibular-evoked myogenic potentials (cVEMP) compared with healthy controls and participants with MCI. Other measures including n23 latency, presence of intact responses, rectified amplitude, mean rectified voltage (measured by cVEMP) and lateral vestibulo-ocular reflex gain (measured by video Head Impulse Test [vHIT]) did not differ between groups. The Timed Up and Go (TUG), Performance-Oriented Mobility Assessment-Balance subscale (POMA-B), and Functional Gait Assessment (FGA) differed significantly between the three groups. Here, more cognitively impaired groups were associated with worse clinical balance scores. CONCLUSIONS: Vestibular and balance deficits were more prevalent in groups with increasing cognitive decline. Regarding vestibular function testing, p13 latency as measured by cVEMP was delayed in participants with AD. Other cVEMP or vHIT measures did not differ between groups. All three clinical balance assessments (TUG, POMA-B, and FGA) resulted in worse scores along the AD continuum. Future research integrating vestibular parameters that add value (including otolith function testing, balance, and spatial navigation) is recommended to validate the association between vestibular function and cognition while avoiding redundant testing.

Electrically evoked compound action potentials are associated with the site of intracochlear stimulation.

OBJECTIVES: Objective measurements to predict the position of a cochlear electrode during cochlear implantation surgery may serve to improve the surgical technique and postoperative speech outcome. There is evidence that electrically evoked compound action potentials (ECAP) are a suitable approach to provide information about the site of stimulation. This study aims to contribute to the knowledge about the association between the intraoperative intracochlear ECAP characteristics and the site of stimulation. METHODS: In a retrospective cohort study, patients undergoing cochlear implant surgery with flexible lateral wall electrode arrays (12 stimulating channels) between 2020 and 2022 were analyzed. The CDL was measured using a CT-based clinical planning software. ECAP were measured for all electrode contacts and associated to the CDL as well as to the site of stimulation in degree. RESULTS: Significant differences among the amplitudes and slopes for the individual stimulated electrode contacts at the stimulation sites of 90°, 180°, 270°, 360°, 450° and 540° were found. The values showed a trend for linearity among the single electrodes. CONCLUSIONS: ECAP characteristics correlate with the electrode's position inside the cochlea. In the future, ECAP may be applied to assess the intracochlear position inside the cochlea and support anatomy-based fitting.

Tinnitus suppression by means of cochlear implantation: does it affect cognition?

PURPOSE: Recent literature suggests that tinnitus can impact cognition, but results were varied due to a diversity in investigated aspects of cognition and utilized tests, as well as the possible influence of confounding factors. The purpose of this study was to assess the impact of tinnitus loudness on cognition by use of a within-subjects design in patients with a cochlear implant (CI). In this population, tinnitus loudness can be modulated by switching the CI on or off as CI is known to highly suppress tinnitus. METHODS: A total of 18 CI users completed two versions of the Repeatable Battery for Assessment of Neuropsychological Status for Hearing Impaired individuals (RBANS-H), once in unaided condition and once in best aided condition. Tinnitus suppression was defined as a difference in score on a visual-analogue scale (VAS) of at least one point out of ten between these two conditions. RESULTS: No significant differences in RBANS-H scores were found between the suppression and no suppression group, nor for the suppression group alone. No significant correlations between tinnitus loudness and RBANS-H were found, neither for the suppression group alone, nor for the group as a whole. CONCLUSION: The current study shows no significant effect of tinnitus loudness on cognition, which contradicts previous literature. This discrepancy could be explained by the use of a within-subjects design, which controls for confounding factors. Future research should include a larger and more diverse study sample to draw definitive conclusions on this topic.

Understanding vessel noise across a network of marine protected areas.

Protected areas are typically managed as a network of sites exposed to varying anthropogenic conditions. Managing these networks benefits from monitoring of conditions across sites to help prioritize coordinated efforts. Monitoring marine vessel activity and related underwater radiated noise impacts across a network of protected areas, like the U.S. National Marine Sanctuary system, helps managers ensure the quality of habitats used by a wide range of marine species. Here, we use underwater acoustic detections of vessels to quantify different characteristics of vessel noise at 25 locations within eight marine sanctuaries including the Hawaiian Archipelago and the U.S. east and west coasts. Vessel noise metrics, including temporal presence and sound levels, were paired with Automatic Identification System (AIS) vessel tracking data to derive a suite of robust vessel noise indicators for use across the network of marine protected areas. Network-wide comparisons revealed a spectrum of vessel noise conditions that closely matched AIS vessel traffic composition. Shifts in vessel noise were correlated with the decrease in vessel activity early in the COVID-19 pandemic, and vessel speed reduction management initiatives. Improving our understanding of vessel noise conditions in these protected areas can help direct opportunities for reducing vessel noise, such as establishing and maintaining noise-free periods, enhancing port efficiency, engaging with regional and international vessel quieting initiatives, and leveraging co-benefits of management actions for reducing ocean noise.

Dual-site transcranial direct current stimulation to treat tinnitus: a randomized controlled trial.

Transcranial direct current stimulation (tDCS) has been proposed as a potential intervention for subjective tinnitus, but supporting evidence remains limited. We aimed to investigate the effect of anodal high-definition tDCS of the left temporal area and right dorsolateral prefrontal cortex on tinnitus severity. This double-blind randomized controlled trial included 77 patients (age range 18-79, 43 male) with chronic subjective tinnitus as their primary complaint. Thirty-eight subjects received six consecutive sessions of dual-site sequential high-definition-tDCS with electrodes positioned over the left temporal area and right dorsolateral prefrontal cortex. Both areas were stimulated for 15 min per session, with total stimulation time amounting to 30 min. Thirty-nine subjects received sham stimulation. The primary outcome measure was the change in tinnitus severity, as evaluated by the Tinnitus Functional Index, from baseline to a follow-up visit at 8 ± 2 weeks after treatment completion. Secondary outcomes included changes in perceived tinnitus loudness, as measured with a visual analogue scale and a tinnitus matching procedure, as well as scores on the Hospital Anxiety and Depression Scale, and the Hyperacusis Questionnaire. No differences in Tinnitus Functional Index change scores were identified between the active treatment and sham control groups (linear regression: P = 0.86). The Tinnitus Functional Index scores decreased significantly over time in both groups (P = 0.0012), indicating the presence of a considerable placebo effect. These change scores were significantly influenced by sex (linear regression: P = 0.037) and baseline symptoms of anxiety (linear regression: P = 0.049) in both groups. In general, Tinnitus Functional Index scores decreased more profoundly in males and in subjects with a higher degree of anxiety at baseline. None of the included secondary measures differed significantly between experimental arms. Our results suggest that dual-site sequential high-definition-tDCS of the left temporal area and right dorsolateral prefrontal cortex does not alleviate tinnitus severity. Interestingly, in our study population, fluctuations in tinnitus severity were influenced by gender and concurrent mental condition. It is therefore important to take these factors into account when conducting or planning randomized controlled trials in tinnitus populations.

Prevalence of tinnitus and hyperacusis in 9-12-year-old children.

OBJECTIVES: To estimate the prevalence of tinnitus and hyperacusis in children aged 9-12 years in Flanders, as well as to explore the associations with hearing abilities and listening behaviours. DESIGN: A cross-sectional survey was undertaken in four different Flemish schools. The questionnaire was distributed among 415 children, with a response rate of 97.3%. RESULTS: The prevalence of permanent tinnitus was 10.5% and of hyperacusis was 3.3%. The hyperacusis prevalence was higher in girls (p < .05). Some children reported effects of tinnitus in terms of anxiety (20.1%), sleep (36.5%), and concentration (24.8%). When listening to personal listening devices, 33.5% of the children reported to listen for at least 1 h at 60% or higher of the volume range. Moreover, 54.9% of children stated to never wear hearing protection. CONCLUSIONS: Tinnitus and hyperacusis are prevalent in children aged 9-12 years. Some of these children might be overlooked and, as such, not receiving the required follow-up or counselling. Development of guidelines for the assessment of these auditory symptoms in children would help to determine the prevalence numbers with greater accuracy. Sensibility campaigns for safe listening are warranted, as more than half of the children never use hearing protection.

Pilot study on the role of somatic modulation in hyperacusis.

BACKGROUND: Hyperacusis is a reduced tolerance to sounds that often co-occurs with tinnitus. Both symptoms have convergent as well as divergent characteristics. Somatic modulation, changes in pitch or loudness during certain movements, is common in patients with a primary complaint of tinnitus. However, thus far, this is not documented in patients with hyperacusis. OBJECTIVES: This study aimed to examine the influence of somatic manoeuvres on the perception of external sounds in patients with a primary complaint of hyperacusis. METHODOLOGY: In this prospective cross-sectional pilot study, 18 patients with a primary complaint of hyperacusis were recruited at the Tinnitus Treatment and Research Center Antwerp (TINTRA). While patients listened to a 1 kHz broadband noise of 30 dB sensation level, six neck manoeuvres (flexion, extension, lateroflexion left/right, traction and compression), three jaw manoeuvres (protrusion, laterotrusion left/right) and one placebo manoeuvre (hand on head) were performed. The primary outcome measure was the change in the perception of the presented sound in terms of loudness and intrusiveness between baseline and each modulation measured by a visual analogue scale (VAS). RESULTS: No overall significant changes were found; however, individual results indicated that five patients presented a clinically relevant change of more than three points out of ten on VAS in terms of hyperacusis after at least one of the executed somatic manoeuvres. CONCLUSIONS: This pilot study did not demonstrate an overall significant change in hyperacusis after somatic manoeuvres but does not rule out the possibility of somatic modulation in some hyperacusis patients. TRIAL REGISTRATION: The protocol of this prospective cross-sectional pilot study was registered on clinicaltrials.gov with registration number NCT04693819.

Automating multi-target tracking of singing humpback whales recorded with vector sensors.

Passive acoustic monitoring is widely used for detection and localization of marine mammals. Typically, pressure sensors are used, although several studies utilized acoustic vector sensors (AVSs), that measure acoustic pressure and particle velocity and can estimate azimuths to acoustic sources. The AVSs can localize sources using a reduced number of sensors and do not require precise time synchronization between sensors. However, when multiple animals are calling concurrently, automated tracking of individual sources still poses a challenge, and manual methods are typically employed to link together sequences of measurements from a given source. This paper extends the method previously reported by Tenorio-Hallé, Thode, Lammers, Conrad, and Kim [J. Acoust. Soc. Am. 151(1), 126-137 (2022)] by employing and comparing two fully-automated approaches for azimuthal tracking based on the AVS data. One approach is based on random finite set statistics and the other on message passing algorithms, but both approaches utilize the underlying Bayesian statistical framework. The proposed methods are tested on several days of AVS data obtained off the coast of Maui and results show that both approaches successfully and efficiently track multiple singing humpback whales. The proposed methods thus made it possible to develop a fully-automated AVS tracking approach applicable to all species of baleen whales.

Contralateral hearing aid use in adult cochlear implant recipients: retrospective analysis of auditory outcomes.

OBJECTIVE: To investigate retrospectively the frequency of usage of bimodal stimulation among cochlear implant (CI) users, as well its clinical benefit relative to unilateral use. DESIGN: All subjects had been monitored with the clinical Minimal Outcome Measurements test battery. STUDY SAMPLES: 103 adults with bilateral postlingual profound sensorineural hearing loss and unilateral CI use were extracted from the local database. These were divided into two groups: those who only used a CI and those who used bimodal stimulation. RESULTS: The preoperative contralateral residual hearing in the bimodal group was significantly better than that of the CI-only group. In both groups, speech perception in quiet and in noise improved after CI, with no significant difference between postoperative unimodal conditions. For the bimodal group, an additional significant improvement was found for the bimodal condition compared to the unimodal. CONCLUSION: Given the observed auditory benefit of bimodal stimulation in comparison to unimodal stimulation and given the finding that degree of residual hearing is not correlated with bimodal benefits, it is recommended to encourage CI recipients to continue contralateral HA use after CI. As a result of expanding CI criteria worldwide, the population of bimodal users is expected to grow in the near future.

The Acoustic Change Complex Compared to Hearing Performance in Unilaterally and Bilaterally Deaf Cochlear Implant Users.

OBJECTIVES: Clinical measures evaluating hearing performance in cochlear implant (CI) users depend on attention and linguistic skills, which limits the evaluation of auditory perception in some patients. The acoustic change complex (ACC), a cortical auditory evoked potential to a sound change, might yield useful objective measures to assess hearing performance and could provide insight in cortical auditory processing. The aim of this study is to examine the ACC in response to frequency changes as an objective measure for hearing performance in CI users. DESIGN: Thirteen bilaterally deaf and six single-sided deaf subjects were included, all having used a unilateral CI for at least 1 year. Speech perception was tested with a consonant-vowel-consonant test (+10 dB signal-to-noise ratio) and a digits-in-noise test. Frequency discrimination thresholds were measured at two reference frequencies, using a 3-interval, 2-alternative forced-choice, adaptive staircase procedure. The two reference frequencies were selected using each participant's frequency allocation table and were centered in the frequency band of an electrode that included 500 or 2000 Hz, corresponding to the apical electrode or the middle electrode, respectively. The ACC was evoked with pure tones of the same two reference frequencies with varying frequency increases: within the frequency band of the middle or the apical electrode (+0.25 electrode step), and steps to the center frequency of the first (+1), second (+2), and third (+3) adjacent electrodes. RESULTS: Reproducible ACCs were recorded in 17 out of 19 subjects. Most successful recordings were obtained with the largest frequency change (+3 electrode step). Larger frequency changes resulted in shorter N1 latencies and larger N1-P2 amplitudes. In both unilaterally and bilaterally deaf subjects, the N1 latency and N1-P2 amplitude of the CI ears correlated to speech perception as well as frequency discrimination, that is, short latencies and large amplitudes were indicative of better speech perception and better frequency discrimination. No significant differences in ACC latencies or amplitudes were found between the CI ears of the unilaterally and bilaterally deaf subjects, but the CI ears of the unilaterally deaf subjects showed substantially longer latencies and smaller amplitudes than their contralateral normal-hearing ears. CONCLUSIONS: The ACC latency and amplitude evoked by tone frequency changes correlate well to frequency discrimination and speech perception capabilities of CI users. For patients unable to reliably perform behavioral tasks, the ACC could be of added value in assessing hearing performance.

Random Forest Classification to Predict Response to High-Definition Transcranial Direct Current Stimulation for Tinnitus Relief: A Preliminary Feasibility Study.

OBJECTIVES: Transcranial direct current stimulation (tDCS) of the right dorsolateral prefrontal cortex has been hypothesized to reduce tinnitus severity by modifying cortical activity in brain regions associated with the perception of tinnitus. However, individual response to tDCS has proven to be variable. We investigated the feasibility of using random forest classification to predict the response to high-definition (HD) tDCS for tinnitus relief. DESIGN: A retrospective analysis was performed on a dataset consisting of 99 patients with subjective tinnitus receiving six consecutive sessions of HD-tDCS at the Antwerp University Hospital. A baseline assessment consisted of pure-tone audiometry and a set of questionnaires including the Tinnitus Functional Index (TFI), Hospital Anxiety and Depression Scale, and Edinburgh Handedness Inventory. Random forest classification was applied to predict, based on baseline questionnaire scores and hearing levels, whether each individual responded positively to the treatment (defined as a decrease of at least 13 points on the TFI). Further testing of the model was performed on an independent cohort of 32 patients obtained from the tinnitus center at the University of Regensburg. RESULTS: Twenty-four participants responded positively to the HD-tDCS treatment. The random forest classifier predicted treatment response with an accuracy of 85.71% (100% sensitivity, 81.48% specificity), significantly outperforming a more traditional logistic regression approach. Performance of the classifier on an independent cohort was slightly but not significantly above chance level (71.88% accuracy, 66.67% sensitivity, 73.08% specificity). Feature importance analyses revealed that baseline tinnitus severity, co-occurrence of depressive symptoms and handedness were the most important predictors of treatment response. Baseline TFI scores were significantly higher in responders than in nonresponders. CONCLUSIONS: The proposed random forest classifier predicted treatment response with a high accuracy, significantly outperforming a more traditional statistical approach. Machine learning methods to predict treatment response might ultimately be used in a clinical setting to guide targeted treatment recommendations for individual tinnitus patients.

Sound localization in patients with bilateral vestibulopathy.

PURPOSE: The goal of this study was to evaluate if bilaterally (partially) absent vestibular function during static sound localization testing, would have a negative impact on sound localization skills. Therefore, this study compared horizontal static sound localization skills of normal-hearing patients with bilateral vestibulopathy (BV) and healthy controls. METHODS: Thirteen normal-hearing patients with BV and thirteen age-matched healthy controls were included. Sound localization skills were tested using seven loudspeakers in a frontal semicircle, ranging from - 90° to + 90°. Sound location accuracy was analyzed using the root-mean-square error (RMSE) and the mean absolute error (MAE). To evaluate the severity of the BV symptoms, the following questionnaires were used: Dizziness Handicap Inventory (DHI), Oscillopsia severity questionnaire (OSQ), 12-item Spatial, Speech, and Qualities Questionnaire (SSQ12), and Health Utilities Index Mark 3 (HUI3). RESULTS: The RMSE and MAE were significantly larger (worse) in the BV group than in the healthy control group, with respective median RMSE of 4.6° and 0°, and a median MAE of 0.7° and 0°. The subjective reporting of speech perception, spatial hearing, and quality of life only demonstrated a moderate correlation between DHI (positive correlation) and HUI total score (negative correlation), and localization scores. CONCLUSION: Static sound localization skills of patients with BV were only mildly worse compared to healthy controls. However, this difference was very small and therefore most likely due to impaired cognitive function. The vestibular system does not seem to have a modulating role in sound localization during static conditions, and its impact is negligible in contrast to the impact of hearing impairment. Furthermore, the subjective reporting of speech perception, spatial hearing, and quality of life was not strongly correlated with localization scores.

Hyperacusis: demographic, audiological, and clinical characteristics of patients at the ENT department.

PURPOSE: To document whether patients with and without hyperacusis differ from each other on demographic, audiological, and clinical characteristics. METHODS: Based on the Hyperacusis Questionnaire's (HQ) cut-off (HQ > 28), a total of 2301 participants were divided into patients with and without hyperacusis. Demographic data, scores on self-reported questionnaires [Tinnitus Functional Index (TFI), Visual Analogue Scale of tinnitus loudness (VASloudness), Hospital Anxiety Depression Scale (HADS)], and audiological parameters were retrospectively analysed to determine differential factors between the two groups. RESULTS: In total, 10.9% of the patients was classified as hyperacusis patients (n = 251). They reported a significant, higher tinnitus severity (mean difference of 19 points on TFI) and mental distress (mean difference of 4 points on the HADS subscales) (p < 0.001) than patients without hyperacusis. Moreover, this group consisted of more women (45% % in hyperacusis group vs. 35% in non-hyperacusis group) and women scored significantly higher on the HQ (p < 0.001) and TFI (p < 0.01). CONCLUSION: Patients with hyperacusis have distinctive characteristics. The presence of hyperacusis in combination with tinnitus can indicate a higher need for psychoeducation. Patients that present themselves with hyperacusis without tinnitus complaints remain a minority, yet might be underdiagnosed. Hence, future studies should disentangle tinnitus from hyperacusis. In clinical practice, greater efforts are required to increase knowledge about hyperacusis as a primary or secondary complaint and to provide individualized treatment for these patients.

Driving ability in patients with dizziness: a systematic review.

PURPOSE: The aim of this systematic review was to identify and evaluate studies dealing with driving performance of dizzy patients or patients with a vestibular disorder. METHODS: A systematic review was performed according to the preferred reporting items for systematic reviews and meta-analysis guidelines. (1) PubMed, Embase, and Cochrane library. (2) Study selection: articles about driving ability and reported driving difficulties in patients with dizziness, or a diagnosed vestibular disorder, were included. (3) Data extraction was performed by two independent authors using predefined data fields: patient's characteristics, diagnostic criteria, sample size, and type of evaluation of driving ability and outcome of the study. RESULTS: Eight out of 705 articles matched the inclusion criteria but varied widely regarding the study population, study design, and outcome measures. The majority of studies reported a negative impact of dizziness and/or vestibular disorders on self-reported driving ability and car accidents. Yet several studies could not identify any impairment of driving ability. CONCLUSIONS: Driving ability was negatively affected by dizziness or a vestibular disorder in the majority of included studies with low risk of bias. This systematic review revealed a significant heterogeneity in studies reporting driving performance and contradictory results. We were, therefore, unable to identify a causal relationship between dizziness and driving ability. There is a need for prospective studies in populations with different vestibular disorders using subjective and objective outcome measures that have been validated to evaluate driving performance.

Multi-target 2D tracking method for singing humpback whales using vector sensors.

Acoustic vector sensors allow estimating the direction of travel of an acoustic wave at a single point by measuring both acoustic pressure and particle motion on orthogonal axes. In a two-dimensional plane, the location of an acoustic source can thus be determined by triangulation using the estimated azimuths from at least two vector sensors. However, when tracking multiple acoustic sources simultaneously, it becomes challenging to identify and link sequences of azimuthal measurements between sensors to their respective sources. This work illustrates how two-dimensional vector sensors, deployed off the coast of western Maui, can be used to generate azimuthal tracks from individual humpback whales singing simultaneously. Incorporating acoustic transport velocity estimates into the processing generates high-quality azimuthal tracks that can be linked between sensors by cross-correlating features of their respective azigrams, a particular time-frequency representation of sound directionality. Once the correct azimuthal track associations have been made between instruments, subsequent localization and tracking in latitude and longitude of simultaneous whales can be achieved using a minimum of two vector sensors. Two-dimensional tracks and positional uncertainties of six singing whales are presented, along with swimming speed estimates derived from a high-quality track.

Variations in received levels on a sound and movement tag on a singing humpback whale: Implications for caller identification.

Bio-logging devices are advancing the understanding of marine animal behavior, but linking sound production and behavior of individual baleen whales is still unreliable. Tag placement potentially within the near field of the sound source creates uncertainty about how tagged animal sounds will register on recorders. This study used data from a tagged singing humpback whale to evaluate this question of how sound levels present on a tag when calls are produced by a tagged animal. Root-mean-square (rms) received levels (RLs) of song units ranged from 112 to 164 dB re 1 µPa rms, with some, but not all, of the lower frequency units registering on the tag's 800 Hz accelerometer sensor. Fifty-nine percent of recorded units measured lower acoustic RLs than previously reported source levels for humpback song, but signal-to-noise ratios (SNRs) were 30-45 dB during periods of the dive with low noise. This research highlights that tag RL does not alone predict caller identity, argues for higher SNR thresholds if using SNR to inform decisions about the source of a call, and provides a baseline for future research identifying diagnostic properties of tagged animal calls in cetacean bioacoustic tag datasets.

The prognostic value and pathophysiologic significance of three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) magnetic resonance imaging in idiopathic sudden sensorineural hearing loss: A systematic review and meta-analysis.

BACKGROUND: The underlying pathophysiology of idiopathic sudden sensorineural hearing loss (ISSNHL) is still unknown. However, an increasing number of observational studies report intralabyrinthine signal alterations in patients with ISSNHL using three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) magnetic resonance imaging (MRI). These findings warrant a meta-analysis. OBJECTIVE OF REVIEW: To conduct a meta-analysis assessing the value of 3D-FLAIR MRI in identifying possible underlying labyrinthine pathophysiologic mechanisms and prognostication in patients with ISSNHL. SEARCH STRATEGY: Two reviewers independently searched the Pubmed, Embase and Cochrane Library from inception until October 10, 2018 and evaluated eligibility based on titles and abstracts of all retrieved studies. All studies reporting on 3D-FLAIR imaging in ISSNHL were included. Subsequently, the full text of eligible studies were evaluated. EVALUATION METHOD: Adhering to the MOOSE guideline, two independent reviewers extracted data, assessed risk of bias and evaluated the relevance and quality of evidence. Data on the number of patients and events were extracted and hearing levels were converted to standardised mean differences (SMD) for conducting meta-analyses. Random effects models for meta-analyses were applied. RESULTS: Eight observational studies met our inclusion criteria (n = 638 patients). In 29%, high signal intensity was found on 3D-FLAIR imaging, suggesting labyrinthine pathology (labyrinthitis [79%], intralabyrinthine haemorrhage [21%]). High signal intensity on 3D-FLAIR was associated with poorer hearing (SMD: 14 dB, 95% CI 5.67-22.94) and vertigo (RR: 1.92, 95% CI 1.16-3.17) at baseline. Multivariate analyses demonstrated that patients with high 3D-FLAIR signal intensity had 21 dB lower final hearing pure-tone averages (SMD: 21 dB, 95% CI 9.08-33.24). CONCLUSIONS: Three-dimensional fluid-attenuated inversion recovery MR imaging can identify an underlying labyrinthine condition in up to 29% of patients with sudden hearing loss in whom previously no cause could be identified. Their final pure-tone averages are more than 20 dB worse than 3D-FLAIR-negative patients, suggesting more severe labyrinthine damage. Findings such as these may contribute to our understanding of pathophysiologic mechanisms of ISSNHL.

Singing whales generate high levels of particle motion: implications for acoustic communication and hearing?

Acoustic signals are fundamental to animal communication, and cetaceans are often considered bioacoustic specialists. Nearly all studies of their acoustic communication focus on sound pressure measurements, overlooking the particle motion components of their communication signals. Here we characterized the levels of acoustic particle velocity (and pressure) of song produced by humpback whales. We demonstrate that whales generate acoustic fields that include significant particle velocity components that are detectable over relatively long distances sufficient to play a role in acoustic communication. We show that these signals attenuate predictably in a manner similar to pressure and that direct particle velocity measurements can provide bearings to singing whales. Whales could potentially use such information to determine the distance of signalling animals. Additionally, the vibratory nature of particle velocity may stimulate bone conduction, a hearing modality found in other low-frequency specialized mammals, offering a parsimonious mechanism of acoustic energy transduction into the massive ossicles of whale ears. With substantial concerns regarding the effects of increasing anthropogenic ocean noise and major uncertainties surrounding mysticete hearing, these results highlight both an unexplored pathway that may be available for whale acoustic communication and the need to better understand the biological role of acoustic particle motion.

Does Primary Productivity Turn Up the Volume? Exploring the Relationship Between Chlorophyll a and the Soundscape of Coral Reefs in the Pacific.

Chlorophyll is the basis for ecosystem productivity in most marine environments. We report on an ongoing effort to examine whether ambient sounds are tied to chlorophyll levels. We hypothesized that an increase in food-web available energy will be distributed across trophic levels, eventually reaching sound-producing animals and increasing acoustic levels. To test our hypothesis, we compared reef environments to explore links between soundscapes and chlorophyll a concentrations. The study sites resided in disparate oceanographic regimes that experienced substantially different oceanographic conditions. We anticipated that the results would show differing patterns of primary productivity between sites and therefore would be reflected in the soundscapes.

Dual instrument passive acoustic monitoring of belugas in Cook Inlet, Alaska.

As part of a long-term research program, Cook Inlet beluga (Delphinapterus leucas) presence was acoustically monitored with two types of acoustic sensors utilized in tandem in moorings deployed year-round: an ecological acoustic recorder (EAR) and a cetacean and porpoise detector (C-POD). The EAR was used primarily to record the calls, whistles, and buzzes produced by belugas and killer whales (Orcinus orca). The C-POD was used to log and classify echolocation clicks from belugas, killer whales, and porpoises. This paper describes mooring packages that maximized the chances of successful long-term data collection in the particularly challenging Cook Inlet environment, and presents an analytical comparison of odontocete detections obtained by the collocated EAR and C-POD instruments from two mooring locations in the upper inlet. Results from this study illustrate a significant improvement in detecting beluga and killer whale presence when the different acoustic signals detected by EARs and C-PODs are considered together. Further, results from concurrent porpoise detections indicating prey competition and feeding interference with beluga, and porpoise displacement due to ice formation are described.