Behavioral Hearing Thresholds Research Articles

Supra-Threshold LS CE-Chirp Auditory Brainstem Response in the Elderly

Introduction: Aging deteriorates peripheral and central auditory structures and functions. In elders, for an accurate audiological evaluation, it is important to explore beyond the cochlear receptor. Audiograms provide an estimation of hearing thresholds, while the amplitudes and latencies of supra-threshold auditory brainstem response (ABR) can offer noninvasive measures of the auditory pathways functioning. Regarding ABR, in young populations, level-specific chirp (LS CE-chirp) stimulus has been proposed as an alternative synchronizing method to obtain larger ABR responses than those evoked by clicks. However, the supra-threshold characteristics of chirp evoked ABR, and their association to hearing thresholds is relatively unknown in the elderly. The aim of this study was to evaluate supra-threshold LS CE-chirp ABRs in an aged population by comparing their features with click ABRs, and evaluating their relationship with audiometric hearing thresholds. Methods: We carried out a cross-sectional study to characterize the hearing of 125 adults aged over 65 years. We determined the audiometric hearing thresholds and supra-threshold ABRs elicited by LS CE-chirp and click stimuli at 80 dB nHL. We evaluated associations by means of partial correlations and covariate adjustment. We performed specific frequencies’ analysis and subgroup analysis per hearing level. Results: Wave V responses had significantly shorter latencies and larger amplitudes when elicited by LS CE-chirp as compared to click-evoked responses. Audiometric hearing thresholds correlated with age, but ABR characteristics did not. We found mild correlations between hearing thresholds and ABR characteristics, predominantly at higher frequencies and with chirp. We found scarce evidence of correlation between ABR characteristics and the average of behavioral hearing thresholds between 0.5 to 4 kHz (0.5–4 kHz PTA). After subgroup analysis according to the hearing level, no stronger or more significant correlations were found between ABR characteristics and 0.5–4 kHz PTA. Discussion: In this study, we found that supra-threshold LS CE-chirp ABR presented some of the previously described similitudes and differences with supra-threshold click ABR in younger populations. Although, the average amplitude and latency of wave V evoked by LS CE-chirp were larger and faster than those evoked by clicks, these results should be taken with caution at the individual level, and further studies are required to state that LS CE-chirp ABRs are better than click ABRs in elders for clinical evaluations. We did not find consistent associations between hearing thresholds and supra-threshold wave V features, suggesting that these measures should be considered independently in the elderly.

Comparison of ASSR and frequency specificity ABR induced by NB CE-Chirp for prediction of behavioral hearing thresholds in children with conductive hearing loss

BackgroundElectrophysiological tests are often used to evaluate hearing loss in infants and young children with conductive hearing loss, no matter to quantify or characterize. However, there are advantages and disadvantages associated with the various electrophysiological tests that are currently available. Therefore, there is no gold standard test. This study aimed to compare the value of narrow-band (NB) CE-Chirp-induced auditory steady-state response (ASSR) and auditory brainstem response (ABR) for assessing hearing thresholds in children with conductive hearing loss. We hope to identify an effective electrophysiological testing method to evaluate conductive hearing loss and provide a reference for clinical hearing assessment of infants with conductive hearing loss. Subjectsand Methods: We selected 27 children (41 ears) aged 3–6 years with otitis media with effusion (OME). Within 1 day, they underwent behavioral audiometry and NB CE-Chirp-induced ASSR and ABR tests in sequence. Pearson's correlation analysis was performed to compare behavioral audiometry thresholds and ASSR and ABR response thresholds at 500, 1000, 2000, and 4000 Hz. ResultsThe behavioral audiometry thresholds of all children were strongly correlated with the response thresholds of the two electrophysiological tests, with correlation coefficients of 0.659, 0.605, 0.723, and 0.857 for ASSR, and 0.587, 0.684, 0.753, and 0.802 for ABR. The proportion of children with a difference of ≤10 dB between ASSR and behavioral audiometry thresholds or between ABR and behavioral audiometry thresholds was not high, especially in the low frequencies. ABR results were superior to ASSR results in terms of predicting actual hearing levels. At 0.5, 1, 2, and 4 kHz, the average differences between the behavioral hearing thresholds and ASSR thresholds in the 41 ears were 5.6, 5.7, 2, and 5.6 dB, respectively. The average differences between behavioral hearing thresholds and ABR thresholds was −5.6, −1.4, −6.8, and 3.2 dB, respectively. The hearing loss configuration of the ASSR exhibited a peaked pattern, similar to behavioral audiometry, whereas the ABR exhibited an ascending pattern. The time to perform the single-ear ASSR test was 5.9 min, whereas the ABR test took 17.0 min. ConclusionASSR and ABR induced by the NB CE-Chirp correlated well with behavioral audiometry in children with conductive hearing loss. The NB CE-Chirp ASSR has advantages in terms of testing time and hearing configuration evaluation, whereas ABR has better reliability than ASSR. However, the stability of ASSR and ABR induced by the NB CE-Chirp is poor, and the thresholds obtained cannot replace behavioral audiometry in evaluating the true hearing of children with conductive hearing loss. However, ASSR and ABR can be used as auxiliary tests for cross-validation.

Utility of electrocochleography for cochlear implant recipients and its potential to predict post-operative hearing thresholds objectively

The relationship between postoperative hearing threshold and CM measured using AIM system developed by Advanced Bionics was investigated in this study. Seven participants (eight ears) with hearing thresholds better than 85 dB HL at 500 Hz were enrolled so far. All were unilaterally or bilaterally implanted with Advanced Bionics HiFocus Mid-Scala or SlimJ electrode arrays. Electrocochleography (ECochG) amplitudes were recorded both intraoperatively and postoperatively at different follow-up sessions. Objective hearing thresholds predicted by the AIM system were compared to the participants’ behavioural hearing thresholds. The trace of CM amplitude showed patterns of either rising or steady responses, except decrease in one case (response amplitude dropped for 12 μV). For the eight participants, the mean difference between the objective hearing levels (ECochG thresholds) measured immediately post-operatively and the preoperative behavioural threshold across 125 Hz, 250 Hz, 500 Hz, and 1000 Hz is 4.90 dB, while its difference to postoperative behavioural threshold is 3 dB. AIM can assist the surgeon to optimize electrode array insertion and thus reduce the possibility of insertion trauma or translocation. Key Words: Hearing preservation, electrocochleography monitoring, cochlear microphonics, cochlear implantation.

Comparison of Click and Level-Specific (LS) CE Chirp-Stimulated Auditory Brainstem Responses in Adults with Hearing Loss.

Background The CE-Chirp stimulus used in the ABR was developed to compensate for the cochlear wave delay. As a version of broadband CE-Chirp stimulus, the use of level-specific (LS) CE-Chirp stimuli, which are created with varying delay models suitable for the intensity levels at which the sound is transmitted, is becoming increasingly common. Purpose The aim of this study was to compare click auditory brainstem responses (ABRs) with LS CE-Chirp ABR thresholds in adults with sensorineural hearing loss. Research Design The research is a cross-sectional-analytical research. Study Sample Twenty-two adult patients (n = 44 ears) with bilateral sensorineural hearing loss were included in the study. Data Collection and Analysis Pure Tone Audiometry (PTA), click ABR and LS CE-Chirp ABR tests were performed on adult (13 male, 9 female) (42.86± 14.50 years) patients with bilateral sensorineural hearing loss. Click ABR and LS CE-Chirp ABR thresholds were compared in terms of proximity to behavioral hearing thresholds of 2 kHz, 4 kHz, and 2-4 kHz averages. Results: Both types of ABR stimuli were able to identify with total hearing loss (n = 6). A statistically significant difference was found between LS CE-Chirp ABR thresholds (53.81±20.28 dB nHL) and click ABR thresholds (58.81±19.11 dB nHL) in the other ears (n = 38) with hearing loss (p=0.00). When both ears were evaluated together and the right and left ears were evaluated separately, no difference was found between LS CE-Chirp ABR thresholds and 4 kHz behavioral hearing thresholds (p: 0.66, p:0.80, p: 0.69, respectively). Conclusion: We determined that in adults with hearing loss, the LS CE-Chirp provides ABR thresholds closer to the behavioral hearing thresholds of 2 kHz, 4 kHz compared to the click stimulus. Notably, there was no difference between LS CE-Chirp ABR thresholds and the 4 kHz behavioral hearing thresholds. We concluded that the LS CE-Chirp stimulus can be used effectively in the estimation of behavioral hearing thresholds in adults with hearing loss Keywords: Auditory Brainstem Response, Hearing loss, Click, Level specific CE-Chirp.

Intracochlear electrocochleography findings in cochlear implant recipients with auditory neuropathy spectrum disorder.

This study aimed to compare intracochlear electrocochleography (ECochG) findings in a group of cochlear implant (CI) recipients with auditory neuropathy spectrum disorder (ANSD) with a group of CI recipients with sensorineural hearing loss (SNHL). Auditory outcome and spectral resolution findings were also compared among CI recipients with and without cochlear microphonic (CM) responses. This single-center, prospective cohort study was undertaken at a tertiary referral center. CM responses by the intracochlear ECochG test were recorded in CI recipients at 0.25-2kHz. Speech, spatial, and hearing quality (SSQ) outcomes and spectral resolution measured with the spectral-temporally modulated ripple test were obtained for each recipient. The study included 62 implanted ears in 46 recipients, of which 59% (n=27) were male and 41% (n=19) were female. Twenty-nine ears with ANSD and 33 ears with SNHL were included. The mean age of the participants was 11 years. The results compared the intracochlear ECochG findings of the ANSD group with those of the SNHL group. Participants were divided into two groups with and without obtainable CM responses. CM responses were obtained in 13 of 29 ears in the ANSD group and 14 of 33 ears in the SNHL group. CM thresholds obtained were better according to behavioral audiometric responses in some frequencies in the ANSD group. No significant difference was found in the auditory outcome and spectral resolution among CI recipients with and without CM responses. Intracochlear ECochG has a limited potential clinical value for monitoring ANSD. CM thresholds obtained using ECochG may not reflect behavioral hearing thresholds.

Hearing in helmeted guineafowl (Numida meleagris): audiogram from 2Hz to 10kHz and localization acuity for brief noise bursts.

Behavioral hearing thresholds and noise localization acuity were determined using a conditioned avoidance/suppression procedure for three Helmeted guineafowl (Numida meleagris). The guineafowl responded to frequencies as low as 2Hz at 82.5dB SPL, and as high as 8kHz at 84.5dB SPL.At a level of 60dB SPL, their hearing range spanned 8.12 octaves (24.6Hz-6.86kHz). Like most birds, they do not hear sounds above 8kHz. However, the guineafowl demonstrated good low-frequency hearing (frequencies below 32Hz), showing thresholds that are more sensitive than both the peafowl and pigeon, both of which hear infrasound. It thus appears that infrasound perception may be more common than previously thought and may have implications for species that inhabit areas with wind energy facilities. The guineafowls' minimum audible angle for a 100-ms broadband noise burst was 13.8 °, at the median for birds and near the mean for mammals. Unlike in mammals, the small sample of bird species and limited representation of lifestyles do not yet allow for meaningful interpretations of the selective pressures or mechanisms that underlie their abilities to locate sound sources.

Behavioral hearing thresholds and response latencies in killer whales (Orcinus orca) depend on sound duration

Large odontocetes are considered at risk of auditory and behavioral impacts from sonar, and it is necessary to predict the effects of tonal sonar signals that have widely varying durations. Here, the effect of sound duration on hearing threshold and reaction time was investigated in two killer whales (Orcinus orca) using behavioral methods. Hearing tests were conducted using sounds between 50 μs and 2 s in duration for frequencies across the hearing range. Hearing thresholds within each frequency were dependent on sound duration, with threshold increasing with duration out to a plateau, which was used to calculate auditory integration time. Vocal response reaction time data showed decreasing latency with increasing signal level and length. These data were consistent with other marine mammal species and demonstrate that signal detection and behavior are affected by the duration of tonal sounds in killer whales.

Automatic audiometry using auditory steady-state response and sequential test strategy applied to volunteers with normal hearing.

In the present study, a new procedure to perform automatic audiometry using multifrequency Auditory Steady-State Response (ASSR) is proposed. The automatic audiometry procedure consists of detecting the presence of multifrequency ASSR in real-time using the sequential test strategy and by adjusting the stimulus intensity independently. The ASSR audiometric thresholds of 18 adult volunteers with normal hearing were determined by automatically (four simultaneous frequencies per ear) at modulation frequencies in the 80Hz range. The exam time and the difference between ASSR thresholds and pure-tone behavioural hearing thresholds were estimated as performance measures. The results showed that automatic audiometry can reduce the number of intensity levels used to obtain the ASSR threshold by up to 58% when compared to audiometry without using the techniques applied in automatic audiometry. In addition, the average of the difference between ASSR thresholds and Pure-Tone Behavioural Hearing thresholds was around 19dB, which is similar to the results reported in similar studies. The audiometric procedure proposed in this study is fully automatic, i.e., does not require any human supervision throughout the exam, and is able to significantly reduce the conventional exam time.

The influence of self-reported noise exposure on 2ƒ1-ƒ2 distortion product otoacoustic emission level, fine structure, and components in a normal-hearing population.

Distortion product otoacoustic emissions (DPOAEs) offer an outcome measure to consider for clinical detection and monitoring outer hair cell dysfunction as a result of noise exposure. This investigation detailed DPOAE characteristics and behavioral hearing thresholds up to 20 kHz to identify promising metrics for early detection of cochlear dysfunction. In a sample of normal-hearing individuals with and without self-reported noise exposure, the DPOAE and hearing threshold measures, as assessed by two questions, were examined. The effects on various auditory measures in individuals aged 10-65 years old with clinically normal/near-normal hearing through 4 kHz were evaluated. Individuals reporting occupational noise exposures (n = 84) and recreational noise exposures (n = 46) were compared to age-matched nonexposed individuals. The hearing thresholds and DPOAE level, fine structure, and component characteristics for the full frequency bandwidth were examined. The data suggest that the DPOAE levels measured using a range of stimulus levels hold clinical utility while fine structure characteristics offer limited use. Under carefully calibrated conditions, the extension to frequencies beyond 8 kHz in combination with various stimulus levels holds clinical utility. Moreover, this work supports the potential utility of the distortion product place component level for revealing differences in cochlear function due to self-reported, casual noise exposure that are not observable in behavioral hearing thresholds.

Noise exposure levels predict blood levels of the inner ear protein prestin

Serological biomarkers of inner ear proteins are a promising new approach for studying human hearing. Here, we focus on the serological measurement of prestin, a protein integral to a human’s highly sensitive hearing, expressed in cochlear outer hair cells (OHCs). Building from recent nonhuman studies that associated noise-induced OHC trauma with reduced serum prestin levels, and studies suggesting subclinical hearing damage in humans regularly engaging in noisy activities, we investigated the relation between serum prestin levels and environmental noise levels in young adults with normal clinical audiograms. We measured prestin protein levels from circulating blood and collected noise level data multiple times over the course of the experiment using body-worn sound recorders. Results indicate that serum prestin levels have a negative relation with noise exposure: individuals with higher routine noise exposure levels tended to have lower prestin levels. Moreover, when grouping participants based on their risk for a clinically-significant noise-induced hearing loss, we found that prestin levels differed significantly between groups, even though behavioral hearing thresholds were similar. We discuss possible interpretations for our findings including whether lower serum levels may reflect subclinical levels of OHC damage, or possibly an adaptive, protective mechanism in which prestin expression is downregulated in response to loud environments.

КОМПЛЕКСНАЯ ДИАГНОСТИКА СЛУХА У ДЕТЕЙ С ЗАБОЛЕВАНИЕМ СПЕКТРА АУДИТОРНЫХ НЕЙРОПАТИЙ В РЕСПУБЛИКЕ БЕЛАРУСЬ

Auditory Neuropathy Spectrum Disorders, ANSD is a state of the auditory system in which the patient has otoacoustic emissions (OAEs) and/or cochlear microphonic potential (CMP), and auditory brainstem responses (ABRs) are absent or significantly reduced. In contrast to sensorineural hearing loss, where the outer and inner hair cells of the cochlea are damaged, in ANSD the outer hair cells are preserved. The complexity of ANSD detection and the variety of clinical symptoms of this disorder make it difficult to differentiate this disease from sensorineural hearing loss. Purpose. Improvement of the differential diagnosis of ANSD and sensorineural hearing loss by defining the main anamnestic and audiological criteria. Materials and methods. The research included 2 groups of patients: the core group - 48 patients with bilateral ANSD and the control group - 30 patients with bilateral chronic sensorineural hearing loss. All patients underwent assessment of the anamnesis data, impedance measurement, tone threshold audiometry, registration of OAE (TEOAE), registration of ABR with allocation of CMP, registration of stationary auditory evoked potentials. Results. In patients with ANSD the incidence of prematurity, low birth weight, and hyperbilirubinemia is significantly higher (p <0.05) than in patients with sensorineural hearing loss. In patients with ANSD the 35delG mutation in the GJB2 gene was not identified, in contrast to patients with sensorineural hearing loss (genetic factor was confirmed in 23.3%) (p <0.05). Newborn hearing screening on both sides was conducted in 15 children (31.3%) with ANSD and only 1 child (3.3%) with sensorineural hearing loss (p <0.05). In 8 patients (16.7%) with ANSD was recorded TEOAE during the initial audiological diagnosis, in contrast to sensorineural hearing loss (TEOAE was not recorded in 100% of patients) (p <0.05). In contrast to sensorineural hearing loss, the ABR thresholds in ANSD did not correspond to the behavioral hearing thresholds. CMP was recorded on the right and left ear in all patients (100%) with ANSD and remained unchanged during the observation process, in contrast to patients with sensorineural hearing loss, in whom CMP was not recorded on both sides (p <0.05). Conclusions. The structure of the main risk factors for hearing loss in children with ANSD and sensorineural hearing loss is different. In the differential diagnosis with sensorineural hearing loss, the possibility of TEOAE disappearance in ANSD should be taken into account. Registration of ABRs with the allocation of CMP is the most informative method of ANSD diagnostics. CMP registration should be conducted for all patients who do not have ABR peaks at the maximum stimulus intensity, regardless of the OAE registration results.

AudioChip: A Deep Phenotyping Approach for Deconstructing and Quantifying Audiological Phenotypes of Self-Reported Speech Perception Difficulties.

About 15% of U.S. adults report speech perception difficulties despite showing normal audiograms. Recent research suggests that genetic factors might influence the phenotypic spectrum of speech perception difficulties. The primary objective of the present study was to describe a conceptual framework of a deep phenotyping method, referred to as AudioChipping, for deconstructing and quantifying complex audiometric phenotypes. In a sample of 70 females 18 to 35 years of age with normal audiograms (from 250 to 8000 Hz), the study measured behavioral hearing thresholds (250 to 16,000 Hz), distortion product otoacoustic emissions (1000 to 16,000 Hz), click-evoked auditory brainstem responses (ABR), complex ABR (cABR), QuickSIN, dichotic digit test score, loudness discomfort level, and noise exposure background. The speech perception difficulties were evaluated using the Speech, Spatial, and Quality of Hearing Scale-12-item version (SSQ). A multiple linear regression model was used to determine the relationship between SSQ scores and audiometric measures. Participants were categorized into three groups (i.e., high, mid, and low) using the SSQ scores before performing the clustering analysis. Audiometric measures were normalized and standardized before performing unsupervised k-means clustering to generate AudioChip. The results showed that SSQ and noise exposure background exhibited a significant negative correlation. ABR wave I amplitude, cABR offset latency, cABR response morphology, and loudness discomfort level were significant predictors for SSQ scores. These predictors explained about 18% of the variance in the SSQ score. The k-means clustering was used to split the participants into three major groups; one of these clusters revealed 53% of participants with low SSQ. Our study highlighted the relationship between SSQ and auditory coding precision in the auditory brainstem in normal-hearing young females. AudioChip was useful in delineating and quantifying internal homogeneity and heterogeneity in audiometric measures among individuals with a range of SSQ scores. AudioChip could help identify the genotype-phenotype relationship, document longitudinal changes in auditory phenotypes, and pair individuals in case-control groups for the genetic association analysis.

PORÓWNANIE SŁUCHOWYCH POTENCJAŁÓW KOROWYCH N1P2 I POTENCJAŁU STANU USTALONEGO GENEROWANEGO WĄSKOPASMOWYM BODŹCEM TYPU CHIRP W ROZPOZNANIU PROGU SŁYSZENIA U OSÓB DOROSŁYCH

BackgroundVarious auditory evoked potential techniques have been explored as a means of objectively predicting the behavioral audiogram in groups of subjects who cannot provide reliable or accurate behavioral results. The tone-evoked auditory brainstem response (ABR) cannot differentiate between severe and profound SNHL, whereas the auditory steady state response (ASSR) can provide threshold information in a frequency-specific manner at intensity levels of 120 dBSPL. The cortical auditory evoked potential (N1P2 CAEP) has shown advantages over the ABR and ASSR.ObjectivesTo assess the ability of the N1P2 cortical auditory evoked potential (CAEP) to estimate the hearing threshold level at different frequencies, in normal hearing adults and adults with different degrees of sensorineural hearing loss (SNHL); and to compare it to the auditory steady state response (ASSR).MethodsThis study included 90 subjects (180 ears), grouped into 6 groups according to the degree of hearing obtained by pure tone audiometry (PTA). Hearing threshold was then measured using N1P2 CAEP and ASSR.ResultsN1P2 CAEP and ASSR were highly correlated to PTA at all frequencies. However, N1P2 CAEP predicted behavioral thresholds more accurately than ASSR at all frequencies, especially at 500 and 1000 Hz in the normal hearing group and for all degrees of SNHL. N1P2 CAEP was equally accurate at all frequencies and predicted behavioral thresholds better at more severe degrees of SNHL at 1, 2, and 4 kHz.ConclusionsThe N1P2 CAEP can be reliably used as an objective method for estimating the behavioral hearing threshold, yielding more accurate results than the ASSR, especially at lower frequencies and with more severe degrees of hearing loss. We therefore recommend using the N1P2 CAEP in estimating the behavioral threshold in difficult-to-test adults.

Characterization of interstimulus interaction in the multiple auditory steady-state responses at high sound levels.

Multiple auditory steady-state response (MASSR) is recommended to estimate hearing thresholds in difficult-to-test individuals. The multiple stimuli that evoke MASSR may present an interstimulus interaction (ISI) that is able to distort the generation of responses. No consensus exists on the effects of the ISI in MASSR when dealing with high sound level stimuli or cases of sensorineural hearing loss. This study investigated the effects of ISI on the amplitude and detectability of auditory steady-state responses, with a focus at and above 65 dB sound pressure level (SPL). Normal hearing (NH) and sensorineural hearing impaired (SNHI) adults were tested with different stimulus types [amplitude modulation (AM) One octave chirp (OC), and a weighted OC (WOC)], stimulus levels, and modalities (single or multiple stimuli). ISI typically attenuated response amplitude of a control stimulus caused by an interference stimulus one octave above the control stimulus. At and above 80 dB SPL, attenuations of around 50% decreased the number of detectable responses near SNHI thresholds, especially for OC and WOC. AM stimuli obtained a higher detection rate than OC and WOC when presented 10 dB above the behavioral hearing threshold of SNHI participants. Using OC in MASSR when assessing elevated thresholds might diminish accuracy on threshold estimation, and extend test duration.

The comparison of changes in hearing thresholds and insertion losses due to occlusion induced by ear impression in sound field assessment

Background and Aim: The methods of deter­mining the amount of sound attenuation by ear mold, earplug or any other foreign body that placed in or out of the ear canal, is divided in subjective and objective. Due to the contradic­tory results in the studies in this field, this study aimed to use more audiometric frequencies con­sidering the strengths and weaknesses of previ­ous studies.
 Methods: This study was conducted on 30 indi­viduals with normal hearing in the age range of 21-26-year-old. First the impression mold was prepared from both ears. The evaluating real ear unaided response and the real ear occluded res­ponse. In the next step, hearing thresholds were assessed by sound field with a precision of 1 dB, once in both open ear and once in both clo­sed ears. Finally, the insertion loss due to mold placement at each frequency was compared with the amount of behavioral threshold changes at the same frequency.
 Results: By using paired t-test at frequencies of 400, 500, 800, 1000, 1500, 1600, 2000, 2500, 3000, 4000, 5000, 6000, 6300 and 8000 Hz, the difference in behavioral hearing thresholds with
 and without molding was greater than the amo­unt of the insertion loss (p < 0.001).
 Conclusion: The insertion loss due to impre­ssion for behavioral assessment at all of the tes­ted frequencies were more than the attenuation in real ear evaluation (p < 0.001). In this regard, consequently the standard deviation of insertion loss due to impression in behavioral threshold condition was more than real ear measurement.
 Keywords: Sound field assessment; insertion loss; real ear occluded response; ear impression; probe microphone measurement; real ear measurement

Association Analysis of Candidate Gene Polymorphisms and Audiometric Measures of Noise-Induced Hearing Loss in Young Musicians.

This study aimed to investigate the association between candidate genetic variants and audiometric measures of noise-induced hearing loss (NIHL) in young musicians. The study analyzed a database by Phillips et al. (Feasibility of a bilateral 4000-6000 Hz notch as a phenotype for genetic association analysis. Int J Audiol 2015;54:645-52.) which included behavioral hearing thresholds, distortion-product otoacoustic emissions (DPOAE), tympanometric, and genetic data of 166 participants meeting the inclusion criteria. Nineteen single nucleotide polymorphisms (SNPs) in 13 cochlear genes previously associated with NIHL in factory workers were included in the present investigation. The average hearing threshold at 3000 and 4000 Hz (AHT) and average DPOAE signal to noise ratio (DPOAE SNR) in both ears were calculated. The regression analyses showed that two SNPs- one in KCNE1 (rs2070358) and the other in CAT (rs12273124) revealed a statistically significant relationship with DPOAE SNR in both ears. Two SNPs in MYH14 and one in GJB4 revealed a significant association with DPOAE SNR in the left ear. Two SNPs in HSP70, one in CDH23 and one in KCNJ10 showed significant association with DPOAE SNR in the right ear. None of the included SNPs showed association with AHT in both ears. A genetic variant in KCNE1 was associated with the strength of the cochlear amplifier as assessed by DPOAE SNR. Musicians carrying causal genetic variants to NIHL might exhibit changes in their auditory functions early in the lifespan even when most subjects had their hearing thresholds within normal limits. These participants are likely to show the clinical manifestation of NIHL in the future if no preventive measures are applied.

Discrepancies in Hearing Thresholds between Pure-Tone Audiometry and Auditory Steady-State Response in Non-Malingerers.

To evaluate discrepancies between pure-tone audiometry (PTA) and auditory steady state response (ASSR) tests in non-malingerers and investigate brain lesions that may explain the discrepancies, especially in cases where the PTA threshold was worse than the estimated ASSR threshold. PTA, speech audiometry, auditory brainstem response, ASSR, and neuroimaging tests were carried out on individuals selected from 995 cases of hearing impairment. Among these, medical records of 25 subjects (19 males, 6 females; mean age = 46.5 ± 16.0 years) with significant discrepancy between PTA and estimated ASSR thresholds were analyzed retrospectively. To define acceptable levels of discrepancy in PTA and ASSR hearing thresholds, 56 patients (27 males, 29 females; mean age = 53.0 ± 13.6 years) were selected for the control group. Magnetic resonance images, magnetic resonance angiograms, and positron emission tomograms were reviewed to identify any neurologic abnormalities. Pathologic brain lesions were found in 20 cases (80%) in the study group, all of which showed a significant discrepancy in hearing threshold between PTA and ASSR. Temporal lobe lesions were found in 14 cases (70%), frontal lobe lesions in 12 (60%), and thalamic lesions without the frontal or temporal lobe in 2 cases (10%). On repeated PTA and ASSR tests a few months later, the discrepancy between ASSR and behavioral hearing thresholds was reduced or resolved in 6 cases (85.7%). Temporal lobe lesions were found in all 3 cases in which the estimated ASSR threshold worsened with unchanged PTA threshold, and frontal lobe lesions were found in all 3 cases in which the PTA threshold improved but the estimated ASSR threshold was unchanged. No neurological lesions were found in 5 cases (20%) of patients with a discrepancy between ASSR and behavioral hearing thresholds. Clinicians should not rely exclusively on ASSR, especially in cases of central nervous system including temporal, frontal lobe, or thalamus lesions. If no lesions are found in a neuroimaging study of a patient with a discrepancy between PTA thresholds and estimated ASSR thresholds, further functional studies of the brain may be needed. If clinicians encounter patients with a discrepancy between PTA thresholds and estimated ASSR thresholds, an evaluation of brain lesions and repeat audiologic tests are recommended in lieu of relying solely on ASSR.

The Association Between Physiological Noise Levels and Speech Understanding in Noise.

Traditionally, elevated hearing thresholds have been considered to be the main contributors to difficulty understanding speech in noise; yet, patients will often report difficulties with speech understanding in noise despite having audiometrically normal hearing. The purpose of this cross-sectional study was to critically evaluate the relationship of various metrics of auditory function (behavioral thresholds and otoacoustic emissions) on speech understanding in noise in a large sample of audiometrically normal-hearing individuals. Behavioral hearing thresholds, distortion product otoacoustic emission (DPOAE) levels, stimulus-frequency otoacoustic emission levels, and physiological noise (quantified using OAE noise floors) were measured from 921 individuals between 10 and 68 years of age with normal pure-tone averages. The quick speech-in-noise (QuickSIN) test outcome, quantified as the signal-to-noise ratio (SNR) loss, was used as the metric of speech understanding in noise. Principle component analysis (PCA) and linear regression modeling were used to evaluate the relationship between the measures of auditory function and speech in noise performance. Over 25% of participants exhibited mild or worse degree of SNR loss. PCA revealed DPOAE levels at 12.5 to 16 kHz to be significantly correlated with the variation in QuickSIN scores, although correlations were weak (R = 0.017). Out of all the metrics evaluated, higher levels of self-generated physiological noise accounted for the most variance in QuickSIN performance (R = 0.077). Higher levels of physiological noise were associated with worse QuickSIN performance in listeners with normal hearing sensitivity. We propose that elevated physiological noise levels in poorer speech in noise performers could diminish the effective SNR, thereby negatively impacting performance as seen by poorer QuickSIN scores.

Normative Data for Cortical Evoked Response Audiometry of a Heterogeneous Indian Population and Its Comparison with Behavioral Audiometry.

Objective:The objective of the study is to establish normative values of cortical evoked response audiometry (CERA) in a heterogeneous Indian population and correlate CERA threshold with pure tone audiometric (PTA) threshold values.Materials and Methods:A prospective study was carried out on 31 volunteers (n = 62) who had no otological or neurological complaints. Two study groups were formed; Group 1 with individuals from 20 to 40 years (mean age of 29.1 years) and Group 2 with individuals from 41 to 60 years (mean age of 46.2 years). The latencies and amplitudes of the waves of P1, N1, and P2 at threshold and 70 dBnHL were measured.Results:Twenty-nine participants (94% of the ears) had CERA threshold within 20 dB of true behavioral threshold with only 6% having a difference of >20 dB with their PTA thresholds. There was a significant difference (P < 0.05) at 70 dB in amplitudes for waves P1, N1, and P2 at 2 kHz and additionally at 1 kHz for N1 between the two groups.Conclusion:Normative values for CERA in a heterogeneous Indian population at 70 dB nHL using tone burst stimulus was found to have an average latency of 46.5, 90.1, and 155.5 ms for P1, N1, and P2, respectively. The average amplitude of P1 at 70 dB nHL was 4.3 μV, N1, was 6.5 μV and P2 was 3.2 μV. Hearing threshold obtained with CERA gave a good indication of the actual behavioral hearing threshold of the normal controls, and the age of an individual had a significant effect on the values obtained during CERA testing with N1 being significantly larger at 1 kHz and 2 kHz in older adults when compared to young adults.

Directional hearing sensitivity for 2-30 kHz sounds in the bottlenose dolphin (Tursiops truncatus).

Bottlenose dolphins (Tursiops truncatus) depend on sounds at frequencies lower than 30 kHz for social communication, but little information on the directional dependence of hearing thresholds for these frequencies exists. This study measured underwater behavioral hearing thresholds for 2, 10, 20, and 30 kHz sounds projected from eight different positions around dolphins in both the horizontal and vertical planes. The results showed that the sound source direction relative to the dolphin affected hearing threshold, and that directional characteristics of the receiving beam pattern were frequency dependent. Hearing thresholds obtained from two adult dolphins demonstrated a positive relationship between directivity of hearing and stimulus frequency, with asymmetric receiving beam patterns in both the horizontal and vertical planes. Projecting sound from directly behind the dolphin resulted in frequency-dependent increases in hearing threshold up to 18.5 dB compared to when sound was projected in front. When the projector was situated above the dolphin thresholds were approximately 8 dB higher as compared to below. This study demonstrates that directional hearing exists for lower frequencies than previously expected.