scholarly journals Predicting synapse counts in living humans by combining computational models with auditory physiology

2020 ◽  
Author(s):  
Brad N. Buran ◽  
Garnett McMillan ◽  
Sarineh Keshishzadeh ◽  
Sarah Verhulst ◽  
Naomi Bramhall
Keyword(s):  
Animal Models ◽  
Otoacoustic Emissions ◽  
Noise Exposure ◽  
Bayesian Regression ◽  
Physiological Data ◽  
Cochlear Function ◽  
Distortion Product ◽  
Speech In Noise ◽  
Auditory Physiology ◽  
Brainstem Response

Aging, noise exposure, and ototoxic medications lead to cochlear synapse loss in animal models. As cochlear function is highly conserved across mammalian species, synaptopathy likely occurs in humans as well. Indeed, temporal bone studies demonstrate loss of synapses with advancing age in humans. Synaptopathy is predicted to result in perceptual deficits including tinnitus, hyperacusis, and difficulty understanding speech-in-noise. However, there is currently no method for diagnosing synaptopathy in living humans. This prevents us from determining if noise-induced synaptopathy occurs in humans, identifying the perceptual consequences of synaptopathy, or testing potential drug treatments. Several physiological measures are sensitive to synaptopathy in animal models, including auditory brainstem response (ABR) wave I amplitude. However, it is unclear how to translate these measures to synaptopathy diagnosis in humans. In this study, a human computational model of the auditory periphery that can predict ABR waveforms and distortion product otoacoustic emissions (DPOAEs) was fit using Bayesian regression analysis to predict synapse counts in individual human participants based on their measured DPOAE levels and ABR wave I amplitudes. Lower predicted synapse numbers were associated with higher noise exposure history, increased likelihood of tinnitus, and poorer speech-in-noise perception. These findings illustrate the utility of this modeling approach in predicting synapse counts from physiological data.

scholarly journals Envelope Following Response Measurements in Young Veterans Are Consistent With Noise-Induced Cochlear Synaptopathy

2020 ◽  
Author(s):  
Naomi Bramhall ◽  
Garnett McMillan ◽  
Sean Kampel
Keyword(s):  
Animal Models ◽  
Otoacoustic Emissions ◽  
Animal Studies ◽  
Noise Exposure ◽  
Auditory Brainstem ◽  
Auditory Nerve Fiber ◽  
Auditory Thresholds ◽  
Distortion Product ◽  
Brainstem Response ◽  
Envelope Following Response

Animal studies have demonstrated that noise exposure can lead to the loss of the synapses between the inner hair cells and their afferent auditory nerve fiber targets without impacting auditory thresholds. Although several non-invasive physiological measures appear to be sensitive to cochlear synaptopathy in animal models, including auditory brainstem response (ABR) wave I amplitude, the envelope following response (EFR), and the middle ear muscle reflex (MEMR), human studies of these measures in samples that are expected to vary in terms of the degree of noise-induced synaptopathy have resulted in mixed findings. One possible explanation for the differing results is that synaptopathy risk is lower for recreational noise exposure than for occupational or military noise exposure. The goal of this analysis was to determine if EFR magnitude and ABR wave I amplitude are reduced among young Veterans with a history of military noise exposure compared with non-Veteran controls with minimal noise exposure. EFRs and ABRs were obtained in a sample of young (19-35 years) Veterans and non-Veterans with normal audiograms and robust distortion product otoacoustic emissions (DPOAEs). Mean EFR magnitudes and ABR wave I amplitudes were reduced for Veterans compared with non-Veteran controls. These findings replicate previous ABR wave I amplitude results in young Veterans and are consistent with animal models of noise-induced cochlear synaptopathy.

Evaluating cochlear function and the effects of noise exposure in the B6.CAST+Ahl mouse with distortion product otoacoustic emissions

2004 ◽  
Vol 194 (1-2) ◽  
pp. 87-96 ◽  
Author(s):  
Ana E Vázquez ◽  
Ana M Jimenez ◽  
Glen K Martin ◽  
Anne E Luebke ◽  
Brenda L Lonsbury-Martin
Keyword(s):  
Otoacoustic Emissions ◽  
Noise Exposure ◽  
Distortion Product Otoacoustic Emissions ◽  
Cochlear Function ◽  
Distortion Product

scholarly journals Subclinical Auditory Dysfunction: Relationship Between Distortion Product Otoacoustic Emissions and the Audiogram

2021 ◽  
pp. 1-16
Author(s):  
Naomi F. Bramhall ◽  
Garnett P. McMillan ◽  
Amy N. Mashburn
Keyword(s):  
Otoacoustic Emissions ◽  
Pure Tone ◽  
Noise Exposure ◽  
Outer Hair Cell ◽  
Self Report ◽  
Distortion Product Otoacoustic Emissions ◽  
Sample Mean ◽  
Distortion Product ◽  
Clinically Normal ◽  
Auditory Physiology

Purpose Distortion product otoacoustic emissions (DPOAEs) and audiometric thresholds have been used to account for the impacts of subclinical outer hair cell (OHC) dysfunction on auditory perception and measures of auditory physiology. However, the relationship between DPOAEs and the audiogram is unclear. This study investigated this relationship by determining how well DPOAE levels can predict the audiogram among individuals with clinically normal hearing. Additionally, the impacts of age, noise exposure, and the perception of tinnitus on the ability of DPOAE levels to predict the audiogram were evaluated. Method Suprathreshold DPOAE levels from 1 to 10 kHz and pure-tone thresholds from 0.25 to 16 kHz were measured in 366 ears from 194 young adults (19–35 years old) with clinically normal audiograms and middle ear function. The measured DPOAE levels at all frequencies were used to predict pure-tone thresholds at each frequency. Participants were grouped by age, self-reported noise exposure/Veteran status, and self-report of tinnitus. Results Including DPOAE levels in the pure-tone threshold prediction model improved threshold predictions at all frequencies from 0.25 to 16 kHz compared with a model based only on sample mean pure-tone thresholds, but these improvements were modest. DPOAE levels for f 2 frequencies of 4 and 5 kHz were particularly influential in predicting pure-tone thresholds above 4 kHz. However, prediction accuracy varied based on participant characteristics. On average, predicted pure-tone thresholds were better than measured thresholds among Veterans, individuals with tinnitus, and the oldest age group. Conclusions These results indicate a complex relationship between DPOAE levels and the audiogram. Underestimation of pure-tone thresholds for some groups suggests that additional factors other than OHC damage may impact thresholds among individuals within these categories. These findings suggest that DPOAE levels and pure-tone thresholds may differ in terms of how well they reflect subclinical OHC dysfunction. Supplemental Material https://doi.org/10.23641/asha.13564745

scholarly journals Auditory brainstem response demonstrates that reduced peripheral auditory input is associated with self-report of tinnitus

2019 ◽  
Author(s):  
Naomi Bramhall ◽  
Garnett McMillan ◽  
Frederick Gallun ◽  
Dawn Konrad-Martin
Keyword(s):  
Animal Models ◽  
Auditory Brainstem Response ◽  
Otoacoustic Emissions ◽  
Auditory Brainstem ◽  
Self Report ◽  
Auditory Input ◽  
Distortion Product ◽  
Brainstem Response ◽  
Temporal Bones ◽  
The Relationship

Tinnitus is one of the predicted perceptual consequences of cochlear synaptopathy, a type of age-, noise-, or drug-induced auditory damage that has been demonstrated in animal models to cause homeostatic changes in central auditory gain. Although synaptopathy has been observed in human temporal bones, assessment of this condition in living humans is limited to indirect non-invasive measures such as the auditory brainstem response (ABR). In animal models, synaptopathy is associated with a reduction in ABR wave I amplitude at suprathreshold stimulus levels. Several human studies have explored the relationship between wave I amplitude and tinnitus, with conflicting results. This study investigates the hypothesis that reduced peripheral auditory input due to synaptic/neuronal loss is associated with tinnitus. ABR wave I amplitude data from 193 individuals (43 with tinnitus (22%), 150 without tinnitus (78%)), who participated in up to three out of four different studies, were included in a logistic regression analysis to estimate the relationship between wave I amplitude and tinnitus at a variety of stimulus levels and frequencies. Statistical adjustment for sex and distortion product otoacoustic emissions was included in the analysis. The results suggest that smaller ABR wave I amplitudes are associated with an increased probability of reporting tinnitus.

Clinical Applications of Otoacoustic Emissions

1991 ◽  
Vol 34 (5) ◽  
pp. 964-981 ◽  
Author(s):  
Brenda L. Lonsbury-Martin ◽  
Martin L. Whitehead ◽  
Glen K. Martin
Keyword(s):  
Otoacoustic Emissions ◽  
Present Report ◽  
Clinical Applications ◽  
Distortion Product Otoacoustic Emissions ◽  
Current View ◽  
Cochlear Function ◽  
Distortion Product ◽  
Auditory Physiology ◽  
Clinical Potential

On the basis of recent advances in auditory physiology, new tests of cochlear function have been developed using measures of otoacoustic emissions. In the present report, the clinical potential for each of the four basic emission types is examined. In addition, the practical advantages of examining the ear with two specific types of evoked emissions, transiently evoked and distortion-product otoacoustic emissions, are reviewed in detail. Finally, the future role of tests of otoacoustic emissions in the diagnosis of hearing impairment is discussed. The current view is that evoked emissions hold promise as an essential part of the clinical examination of the auditory system.

scholarly journals Determinants of the Audiometric Notch at 4000 and 6000 Hz in Young Adults

2020 ◽  
Vol 31 (06) ◽  
pp. 371-383
Author(s):  
Ishan Sunilkumar Bhatt
Keyword(s):  
Young Adults ◽  
Otoacoustic Emissions ◽  
Noise Exposure ◽  
Hearing Threshold ◽  
Calibration Error ◽  
Cochlear Function ◽  
Cross Sectional ◽  
Distortion Product ◽  
Hearing Thresholds ◽  
Children And Young Adults

Abstract Background Noise-induced hearing loss (NIHL) is often characterized by the presence of an audiometric notch at 3000-6000 Hz in a behavioral audiogram. The audiometric notch is widely used to investigate NIHL in children and young adults. However, the determinants of the audiometric notch in young adults largely remain unknown. Purpose The study aimed to investigate the determinants of the audiometric notch in young adults. Research Design A cross-sectional design was adopted for the study. Study Sample A sample of 124 adults (38 males and 86 females) aged 18-35 years with normal otoscopic and tympanometric findings was recruited. Data Collection and Analysis Hearing thresholds and real-ear sound pressure levels (RESPLs) were obtained with calibrated ER-3A (Etymotic Research, Elk Grove Village, IL) andTDH-50P receivers (Telephonics, Farmingdale, NY). Distortion-product otoacoustic emissions (DPOAEs) were used to evaluate the cochlear function. The external auditory canal (EAC) length was measured using the acoustical method. Noise exposure background (NEB) was estimated using the Noise Exposure Questionnaire. The notched audiograms were identified using: Phillips, Coles, and Niskar criteria. Results The prevalence of notched audiograms was substantially higher for TDH-50P supra-aural receivers than for ER-3A insert receivers. RESPLs at 6000 and 8000 Hz were the major predictors of notched audiograms for TDH-50P receivers. These predictors explained around 45% of the variance in the notched audiograms. The notched audiograms obtained with TDH-50P receivers showed no association with NEB. Individuals with notched audiograms measured using TDH-50P did not show convincing evidence of cochlear dysfunction as assessed by DPOAEs. Individuals with notched audiograms obtained with TDH-50P receivers revealed an average of shorter EAC and a poorer hearing threshold at 6000 Hz. Conclusions The calibration error in the RESPLs at 6000 and 8000 Hz that are likely to be influenced by the shorter EAC was the major determinant of the notched audiograms when the supra-aural transducers were used to measure hearing thresholds. Therefore, the supra-aural receivers should not be used to estimate the prevalence of NIHL in children and young adults when the less restrictive notch identification criteria are used to identify NIHL. Real-ear calibration techniques that are least influenced by the standing waves in the EAC should be preferred when investigating the prevalence of and risk factors for NIHL in young adults.

Vocal Performance Teachers and Hearing Loss

2015 ◽  
Vol 16 (1) ◽  
pp. 15-24
Author(s):  
Vance Gunnell ◽  
Jeff Larsen
Keyword(s):  
Hearing Loss ◽  
Otoacoustic Emissions ◽  
Noise Exposure ◽  
Vocal Performance ◽  
Occupational Noise ◽  
Hearing Conservation ◽  
Occupational Noise Exposure ◽  
Distortion Product ◽  
Hearing Thresholds ◽  
Performance Teachers

Hearing thresholds and distortion product otoacoustic emissions were measured for teachers of vocal performance who were gathered for a national conference. Results showed mean audiometric thresholds to be consistent with noise induced hearing loss, more than what would be expected with normal aging. Years of instruction and age were considered as factors in the hearing loss observed. It was concluded that hearing conservation should be initiated with this group to help raise awareness and protect them from hearing loss due to occupational noise exposure.

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