Peripheral Hearing Sensitivity Research Articles

Resistance to age-related hearing loss in the echolocating big brown bat ( Eptesicus fuscus ).

Hearing mediates many behaviors critical for survival in echolocating bats, including foraging and navigation. Most mammals are susceptible to progressive age-related hearing loss; however, the evolution of biosonar, which requires the ability to hear low-intensity echoes from outgoing sonar signals, may have selected against the development of hearing deficits in echolocating bats. Although many echolocating bats exhibit exceptional longevity and rely on acoustic behaviors for survival to old age, relatively little is known about the aging bat auditory system. In this study, we used DNA methylation to estimate the ages of wild-caught big brown bats ( Eptesicus fuscus ) and measured hearing sensitivity in young and aging bats using auditory brainstem responses (ABRs) and distortion product otoacoustic emissions (DPOAEs). We found no evidence for hearing deficits in aging bats, demonstrated by comparable thresholds and similar ABR wave and DPOAE amplitudes across age groups. We additionally found no significant histological evidence for cochlear aging, with similar hair cell counts, afferent, and efferent innervation patterns in young and aging bats. Here we demonstrate that big brown bats show minimal evidence for age-related loss of peripheral hearing sensitivity and therefore represent informative models for investigating mechanisms that may preserve hearing function over a long lifetime.

19 Auditory and Cognitive Function in Adults Living With and Without HIV

Objective:Hearing consists of peripheral components (outer and middle ear, cochlea) and the central auditory system (cochlear nuclei to the auditory cortex). Speech perception relies on peripheral hearing abilities (i.e., pure-tone thresholds) and central auditory processing (CAP) and cognitive functioning. Specifically, working memory, executive function, attention, and verbal functioning allow for speech understanding. As a result, CAP deficits are also influenced by peripheral hearing sensitivity and cognitive functioning. Assessing CAP deficits can be difficult because of these complex interactions. Prior work has shown persons living with HIV (PWH) are at higher risk for sensorineural hearing loss compared to persons living without HIV (PWOH) after adjusting for age, sex, and noise exposure. Further, HIV is a risk factor for cognitive impairment, one example being Alzheimer's disease (AD) and its precursor, Mild Cognitive Impairment (MCI), with auditory dysfunction occurring in earlier stages of AD. Therefore, the purpose of this study was to evaluate: 1) the peripheral hearing sensitivity and CAP in PWH and PWOH; and 2) the association between cognitive function measures and CAP in PWH and PWOH.Participants and Methods:Participants included 59 PWH (39 men and 20 women, mean age=66.7 years [SD=4.4 years]) and 27 PWOH (13 men and 14 women, mean age=71.9 years [SD=7.1 years]). Participants completed a standard neuropsychological battery assessing the domains of learning, recall, executive function, working memory, verbal fluency, processing speed and motor. Raw scores were transformed to demographically corrected, domain T-scores. Cognitive function was normal for 39 (66.1%) PWH and 16 (59.3%) PWOH while 43 (72.9%) PWH and 17 (63.0%) PWOH were determined to have MCI. Participants with dementia were excluded. Participants also completed a hearing assessment, a portion of which consisted of pure-tone thresholds, peripheral hearing measure, and dichotic digits testing (DDT), a CAP measure. Pure-tone air-conduction thresholds were obtained at octave frequencies from 0.25 through 8 kHz, including 3 and 6 kHz. A pure-tone average (PTA) was calculated from 0.5, 1, 2, and 4 kHz thresholds for each ear. The DDT involves the presentation of numbers from 1 to 10, excluding 7, in which two different digits are presented to one ear while two other digits are simultaneously presented to the opposite ear. The outcome of DDT is percent correct.Results:PWH had slightly lower (i.e., better) mean PTAs in both ears compared to PWOH, but this was not statistically significant. Conversely, PWH had lower percent correct DDT results compared to PWOH, but this difference was also not statistically significant. Participants with impairment in verbal fluency, executive functioning, and working memory had significantly worse DDT results by approximately 10%, but only for right ear data.Conclusions:PWH in our sample had better hearing than PWOH, which can be explained by PWH having a lower mean age. PWH had poorer DDT results, however, indicative of CAP deficits rather than peripheral hearing problems. Poor right ear DDT was associated with impairments specifically in frontal-based cognitive processes with an executive component.

The impact of menopausal status on auditory brainstem responses

ObjectiveTo determine the effect of decreased estrogen levels due to menopause on auditory brainstem response measurements (ABR). Study designRetrospective chart review. SettingAcademic. PatientsPre- and post-menopausal females (pre-M, post-M) and age-matched males. MethodsABR measurements of wave I, III, and V latencies, and interpeak latencies; amplitudes of waves I, III, V, and V/I ratio. Outcome measureDifferences in ABR measurements between pre-M and post-M. Results164 subjects (101 female and 64 male) were included. Post-M had significantly greater latencies (msec) than pre-M of wave V. Post-M had a significantly smaller wave I amplitude (uV) than pre-M. Post-M had a significantly higher wave V/I amplitude ratio than pre-M. Pre-M had significantly shorter latencies than young males for wave III, and wave V. Post-M had significantly shorter latencies than older males at wave III, and wave V. A two-way ANOVA revealed a significant interaction between the effects of age category and gender on V/I amplitude. ConclusionPost-M group showed a significant drop in wave I amplitude compared with pre-M group, even in the absence of hearing loss, suggesting that the gender differences in hearing are related to estrogen signaling along the auditory pathway. If wave I amplitude changes between older and younger groups resulted from decreased peripheral hearing sensitivity, we would expect larger drops in amplitude in males since rates of presbycusis are higher. We observed much larger drops in wave I amplitude in females, which cannot be attributed to peripheral hearing loss. These results may assist in understanding gender differences in presbycusis and a possible protective effect of estrogen on the auditory system. Knowledge of gender differences in wave I may be important when ABR is used to assess possible synaptopathy.

Effects of Adding Monaural and Binaural Noise to a Dichotic Listening Task.

The Dichotic Digits Test (DDT) evaluates central auditory nervous system (CANS) dysfunction. The DDT is widely used in audiology clinics worldwide because it is clinically efficient and has good sensitivity and specificity for CANS lesions. However, the DDT shows a strong ceiling effect, which can mitigate its ability to detect subtle CANS dysfunction. This study examines the effects of adding monaural and binaural speech-spectrum noise to the DDT in an effort to make the test more taxing to the CANS and thereby reduce the observed ceiling effect. This was an experimental repeated measures study. The participants were 20 adults aged 18-50 years with normal, bilaterally symmetric peripheral hearing sensitivity. Each participant was administered one standard DDT test list (no noise added) and DDT test lists with binaural, monaural right, and monaural left noise added. For each of the noise-added conditions, lists were administered at two different signal-to-noise ratios (SNRs), for a grand total of seven DDT test lists per participant, presented in randomized order. Monaural and binaural noise effects on DDT scoring indices (Right and Left Ear Percent Correct Scores, Combined Total Percent Correct Scores, and Dichotic Difference Scores), as well as noise effects on the Right Ear Advantage (REA) for speech, were examined. Mixed model analyses of variance (ANOVAs) were used to examine fixed effects and interactions of Noise Condition and Ear. Adding noise to the standard DDT systematically reduced Right and Left Ear Percent Correct Scores and Combined Total Percent Correct Scores. Statistically significant differences on all indices were found between monaural and binaural noise-added conditions, suggesting a possible advantage for binaural listening in noise. These findings suggest that adding noise to tests of dichotic listening increases the difficulty of the task, and that further investigation of dichotic listening patterns in noise could potentially lead to more sensitive clinical evaluations of CANS integrity and function.

Mismatch Negativity and Auditory Brain Stem Response in Children with Autism Spectrum Disorders and Language Disorders.

Language disorders (LD) in autism spectrum disorders (ASD) are highly variable and has a severe impact on the level of functioning in autistic children. Early diagnosis of these language disorders is essential for early interventions for children at risk. The electrophysiological measurements are considered valuable tools for determining language disabilities in children with ASD. This study aimed to study and compare ABR and MMN in autistic children with language disorders. This study included a group of typically developing children and a group of children diagnosed with autistic spectrum disorders and language disorders. Both groups were matching according to age and gender. After confirming bilateral normal peripheral hearing sensitivity, ABR was done and both absolute and interpeak wave latencies were correlated. MMN using frequency oddball paradigms were also obtained and correlated. More abnormalities were reported in ABR test results in the form of delayed absolute latencies and prolonged interpeak intervals. Also, we reported prolonged latencies of MMN. Consequently, both ABR and MMN are complementary test in evaluating autistic children with language disorders. Our results support the hypothesis of remarkable dysfunction in basic auditory sound processing that may impact the linguistic development of autistic children.

The Effect of Speech Perception in Noise on Arabic and Spanish Bilingual Listeners.

The purpose of this study was to compare speech perception performance in noise, as measured by signal-to-noise ratio for 50% correct scores (SNR-50) and SNR loss, between monolingual English speakers and two bilingual second-language learner populations with normal hearing sensitivity: Arabic-English and Spanish-English bilinguals. Additionally, this study observed how speech perception in noise varied as a function of language dominance for the Arabic-English bilinguals. This study was a quasi-experimental, nonrandomized study. Adults with normal peripheral hearing sensitivity participated in this study: Group 1 (n = 16) bilingual Arabic-English speakers who learned English as a second language; Group 2 (n = 10) bilingual Spanish-English speakers from a previous study; Group 3 (n = 27) monolingual English speakers combined from this study and the study of Mendel and Widner (2016). Speech perception was assessed using standardized methods for the Quick Speech-in-Noise (QuickSIN), the Bamford-Kowal-Bench Speech-in-Noise, the Hearing in Noise Test (HINT), and the Words-in-Noise tests. The two bilingual groups had significantly higher SNR-50 scores and greater SNR loss as compared to their monolingual peers. SNR-50 negatively correlated with language dominance for the QuickSIN and HINT for the Arabic-English speakers. Despite having normal hearing and being proficient in the English language, bilingual Arabic-English and Spanish-English speakers exhibited a mild SNR loss. Speech perception abilities were affected by test difficulty as well as the individual's degree of language dominance.

Documentation of Peripheral Auditory Function in Studies of the Auditory P300 Response

Abstract: A critical review was conducted to examine whether the peripheral hearing status of participants with neurological and psychological disorders was documented in published clinical studies of the auditory P300 response. Literature searches were conducted with three databases: PubMed, PsycINFO, and Scopus. Studies of participants with seven neurological or psychological disorders were included in the study. Each disorder was coupled with the main search phrase in separate searches on each database. Of the total 102 papers which met the inclusion criteria, the majority (64%) did not describe the peripheral hearing sensitivity of participants. In this review with studies that included participants at risk for hearing impairment, particularly age-related hearing loss, only a single publication adequately described formal hearing evaluation. Peripheral hearing status is rarely defined in studies of the P300 response. The inclusion of participants with a hearing loss likely affects the validity of findings for these studies. We recommend formal hearing assessment prior to inclusion of participants in studies of the auditory P300 response. The findings of this study may increase the awareness among researchers outside the field of audiology of the effects of peripheral hearing loss on the auditory P300.

Effect of Temperature on the Plasticity of Peripheral Hearing Sensitivity to Airborne Sound in the Male Red-Eared Slider Trachemys scripta elegans

Chelonians are considered the least vocally active group of extant reptiles and known as “low-frequency specialists” with a hearing range of <1.0 kHz. As they are ectothermic organisms, most of their physiological and metabolic processes are affected by temperature, which may include the auditory system responses. To investigate the influence of temperature on turtle hearing,Trachemys scripta eleganswas chosen to measure the peripheral hearing sensitivity at 10, 20, 30, and 40°C (close to the upper limit of heat resistance) using the auditory brainstem response (ABR) test. An increase in temperature (from 10 to 30°C) resulted in improved hearing sensitivity (a wider hearing sensitivity bandwidth, lower threshold, and shorter latency) inT. scripta elegans. At 40°C, the hearing sensitivity bandwidth continued to increase and the latency further shortened, but the threshold sensitivity reduced in the intermediate frequency range (0.5–0.8 kHz), increased in the high-frequency range (1.0–1.3 kHz), and did not significantly change in the low-frequency range (0.2–0.4 kHz) compared to that at 30°C. Our results suggest that although the hearing range of turtles is confined to lower frequencies than that in other animal groups, turtle hearing showed exceptional thermal regulation ability, especially when the temperature was close to the upper limit of heat resistance. Temperature increases that are sensitive to high frequencies imply that the males turtles’ auditory system adapts to a high-frequency sound environment in the context of global warming. Our study is expected to spur further research on the high-temperature plasticity of hearing sensitivity in diverse taxa or in the same group with different temperature ranges. Moreover, it facilitates forecasting the adaptive evolution of the auditory system to global warming.

The Onset-Offset N1-P2 Cortical Auditory Evoked Response in Individuals With High-Frequency Sensorineural Hearing Loss: Responses to High- and Low-Frequency Narrowband Noise.

This study aimed to determine whether onset-offset N1-P2 auditory evoked responses differ in amplitude, latency, and offset-to-onset trough-to-peak N1-P2 amplitude ratios (OOAR) between normal hearing (NH) sensitivity and moderate high-frequency sensorineural hearing loss (HFSNHL) groups when stimuli target regions of peripheral hearing sensitivity where the groups are in the normal range (i.e., 500 Hz) versus where they differ regarding presence of hearing loss (i.e., 4000 Hz). Onset-offset N1-P2 auditory evoked responses were measured from 10 participants with normal hearing sensitivity and seven participants with moderate HFSNHL using 500-Hz and 4000-Hz narrowband noise (NBN) stimuli. Stimuli were 2000 ms with 40-ms rise-fall times presented at 50 dB SL referenced to stimulus behavioral thresholds. Amplitudes and latencies were analyzed for N1 and P2 onset and offset components via repeated measures analysis of variance (ANOVA). OOARs were compared between groups using one-way ANOVA and across stimuli per group using paired samples t tests. Despite dB SPL stimulus presentation differences between groups, there were no significant differences in individual/absolute amplitude and latency waveform components between groups for either stimulus. Derived comparative calculations of OOAR for 4000-Hz NBN were significantly larger (p < .025; NH: .39; HFSNHL: .62) for the group with HFSNHL than the group with NH sensitivity; 500-Hz NBN OOAR did not reach significance. OOARs revealed no significant difference between stimuli for the group with normal hearing sensitivity, with .38 OOAR for both stimuli (p = .961). OOAR comparisons for the HFSNHL group across stimuli were significant (p = .012), with the 4000-Hz NBN OOAR being nearly double the size of the 500-Hz NBN OOAR. OOARs may provide insight to the balance of excitatory and inhibitory neural firing in the central auditory nervous system (CANS). Larger OOARs may be a biomarker of reduced CANS inhibition, perhaps indicative of a homeostatic central auditory gain mechanism.

Cortical and subcortical processing of speech in cochlear implant recipients with Auditory Neuropathy Spectrum Disorder

Abstract Background Cochlear implantation (CI) is now recognized as one of the possible lines of interventions in ANSD patients to improve their hearing and speech communication. Desynchronized of the auditory information is the most widely accepted mechanism in ANSD. Objectives To study speech processing in the brainstem level as measured by speech-auditory brainstem response (S-ABR) in ANSD and CAEP P1 in ANSD subjects fitted with CIs and the results will be compared to SNHL subjects fitted with unilateral CIs. Subjects and method A total number of 45 subjects were included classified into three groups (one control and two study groups). The control group 16 subjects, age ranged from 5 to 29.5 years with mean of (11.1 years) with normal peripheral hearing sensitivity. The study group comprised 29 children who underwent cochlear implantation. It was subdivided into two subgroups: Group (SNHL) ;their age ranged from2.9 to 15.5 years with mean of (7.7 years) and group (ANSD); Their age ranged from 3.2 to 29 years with mean of (9.3 years) They were subjected to detailed history taking, aided warble-tone sound field audiometry, Questionnaire and Speech-evoked potentials (P1 &amp;c-ABR) recording evoked by the 150-ms synthesized /da/ syllable stimulus. Results C-ABR waves were detected in 100% of control group, 75% of SNHL group and 53.8% of ANSD group. A statistically significant differences existed between the control group and the two study subgroups regarding the P1 latencies. While; there were no statistically significant differences between {SNHL group &amp;ANSD}. Sound-field S-ABR in the CI recipients showed delayed latencies in both SNHL group &amp;ANSD group comparable to the control group with more delay in ANSD group than SNHL group. Finally, the neural phase locking was significantly higher in CI recipients due to electrical artifact. Conclusions • There were no statistically significant differences between {SNHL group &amp; ANSD group} regarding P1 latency. • C-ABR waves were detected in 75% of SNHL group and 53.8% of ANSD group with delayed latencies and higher amplitude than control group with more delay in ANSD group than SNHL group. The findings of sound-field S-ABR demonstrated that CI recipients have neural encoding deficits in temporal and spectral domains at the brainstem level; therefore, the sound-field S-ABR can be considered an efficient clinical procedure to assess the speech processing in ANSD subjects fitted with cochlear implant.

Ocular and auditory abnormalities in patients with vitiligo: a case-control study.

Vitiligo is characterized by the destruction of functional melanocytes in the skin. This destruction can target melanocytes anywhere in the body, in turn affecting the function of the organs in which the affected melanocytes reside. Melanocytes in the skin, uveal tract and ear are similar in their physiology and morphology, and share a common embryological origin. To study the association of vitiligo with ocular and auditory abnormalities. This case-control study was carried out on 40 patients with vitiligo and 20 healthy controls (HCs). All patients and HCs underwent auditory examination (otoscopic examination and immittance audiometry to assess middle ear pressure and exclude tympanic membrane perforation; pure tone audiometry to assess peripheral hearing sensitivity; and transient evoked otoacoustic emissions to assess central hearing ability) and standard ocular examination including visual acuity test, slit lamp biomicroscopy and optical coherence tomography. Compared with controls, there was a significantly higher prevalence of hearing loss and ocular abnormalities in patients with vitiligo but no significant difference in visual acuity. Vitiligo is a systemic disease that can be associated with impairment of melanocyte function organs other than the skin, including the eyes and ears. The function of auditory melanocytes is related to the hearing process and thus their destruction could lead to hearing impairment. By contrast, ocular melanocytes do not play a direct role in detection or transfer of visual information, and thus should not affect vision. Vitiligo may be associated with ocular abnormalities and hearing loss.

Speech evoked potentials in cochlear implant recipients with auditory neuropathy spectrum disorder

Purpose Cochlear implantation (CI) is now recognised as the most possible approach to help ANSD patients in improving their capability in hearing and speech communication. Because there are no reliable methods in clinical practice to identify the exact lesion site and mechanisms for a certain ANSD patient, the efficacy of CI is difficult to predict before surgery. This study was done to study speech ABR and CAEP P1 in ANSD subjects fitted with CIs and to compare results of both tests in ANSD versus SNHL subjects fitted with unilateral CIs, then correlate between both tests in both types of hearing loss. Method The current study was a case-control study, conducted on a total number of 45 subjects who were classified into three groups (one control and two study groups). The control group comprised 16 subjects with normal peripheral hearing sensitivity (NH group) who were age matched to both study groups. The study group comprised 29 children who underwent cochlear implantation. The study group were subdivided according to preoperative diagnosis of the type of their hearing loss into two groups (a group of children with sensorineural hearing loss; SNHL-CI) and (a group of children with Auditory neuropathy spectrum disorder; ANSD-CI). Both study groups were subjected to detailed history taking, aided warble-tone sound field audiometry, Speech-evoked potentials (P1 & ABR) and Questionnaire. Results There were statistically significant differences between the control group and both study subgroups regarding the P1 latencies. While; there were no statistically significant differences between {SNHL-CI group &ANSD-CI}. S-ABR waves were detected in 100% of control group, 75% of SNHL-CI group and 53.8% of ANSD-CI group. Sound-field S-ABR measured in the CI recipients indicated statistically significant delayed latencies than in the NH group. In addition, these results demonstrated that the frequency following response peak amplitude was significantly higher in CI recipients, than in the NH counterparts. Finally, the neural phase locking was significantly higher in CI recipients. Conclusion The findings of sound-field S-ABR demonstrated that CI recipients have neural encoding deficits in temporal and spectral domains at the brainstem level; therefore, the sound-field S-ABR can be considered an efficient clinical procedure to assess the speech processing in CI recipients.

Audio-Vestibular Findings in Patients with Hyperuricemia

Background: Hyperuricemiais a common biochemical disturbance in which serum concentration of uric acid exceeds the normal values which is 7.0 mg/dl in men and more than 6.0 mg/dl in women leading to deposition of monosodium urate [MSU] crystals in joints and soft tissues resulting in inner ear functions affection. Aim of the work: To elaborate the effect of hyperuricemia on the peripheral hearing as well as peripheral vestibular functions. Subjects and Methods: This study included 40 subjects with hyperuricemia and 40 healthy controls. Participants underwent serum uric acid assay, full history taking, basic audiological evaluation and vestibular evaluation. Results: 37[92.5%] hyperuricemic subjects had normal peripheral hearing sensitivity, only 3[7.5%] had mild high frequencies sensori-neural hearing loss [SNHL] at 8 kHz. 31[77.5%] Hyperuricemic patients had normal peripheral vestibular functions, only 9[22.5%] subjects had BPPV; They also had higher serum uric acid [SUA] level. No correlation between duration of hyperuricemia and occurrence of BPPV. Conclusions: The hyperuricemic subjects had a significant higher incidence of BPPV. Other investigations to detect early and subtle changes in cochlear function of hyperuricemic subjects were recommended.

Neurodegenerative Diseases and the Auditory-Vestibular System

Neurodegenerative Diseases and the Auditory-Vestibular System

Effects of frontal-executive dysfunction on self-perceived hearing handicap in the elderly with mild cognitive impairment.

It is increasingly agreed upon that cognitive and audiological factors are associated with self-perceived hearing handicap in old adults. This study aimed to compare self-perceived hearing handicap among mild cognitive impairment (MCI) subgroups and a cognitively normal elderly (CNE) group and determine which factors (i.e., demographic, audiometric, or neuropsychological factors) are correlated with self-perceived hearing handicap in each group. A total of 46 MCI patients and 39 hearing threshold-matched CNE subjects participated in this study, and their age ranged from 55 to 80 years. The MCI patients were reclassified into two groups: 16 with frontal-executive dysfunction (FED) and 30 without FED. All subjects underwent audiometric, neuropsychological, and self-perceived hearing handicap assessments. The Korean version of the Hearing Handicap Inventory for the Elderly (K-HHIE) was administered to obtain the hearing handicap scores for each subject. After controlling for age, years of education, and depression levels, we found no significant differences in the K-HHIE scores between the MCI and the CNE groups. However, after we classified the MCI patients into the MCI with FED and MCI without FED groups, the MCI with FED group scored significantly higher than did both the MCI without FED and the CNE groups. In addition, after controlling for depression levels, significant partial correlations of hearing handicap scores with frontal-executive function scores and speech-in-noise perception performance were found in the MCI groups. In the CNE group, the hearing handicap scores were related to peripheral hearing sensitivity and years of education. In summary, MCI patients with FED are more likely to experience everyday hearing handicap than those without FED and cognitively normal old adults. Although educational level and peripheral hearing function are related to self-perceived hearing handicap in cognitively normal old adults, speech-in-noise perception and frontal-executive function are mainly associated with hearing handicap in patients with MCI.

CI Programming in Patients with Neurologic Impairment

CI Programming in Patients with Neurologic Impairment

Video head impulse test in different age groups

Background and objectiveThe head impulse test is a well-known clinical test that uses video-oculography to quantify vestibulo-ocular reflex (VOR). Normative data for VOR gain are accessible, but most studies just report horizontal-plane VOR characteristics, overlooking variations in vertical-plane VOR gains. The aim of this study is to supply normative data for different age groups to permit future comparison of results to the matching norms.Patients and MethodsThe study was accomplished on 50 individuals who have normal peripheral hearing sensitivity, no otological disorder, and have no history of vestibular disorder, and were divided according to age into five groups, each one comprising 10 participants: individuals in the first group were aged 10–25 years, individuals in the second group were aged 25–35 years, individuals in the third group were aged 35–45 years, individuals in the fourth group were aged 45–55 years, and individuals in the fifth group were aged more than 55 years. Video head impulse test was done using GN Otometrics ICS Impulse in the lateral, left anterior right posterior, and right anterior left posterior semicircular canal planes.ResultsThis study demonstrated that age has no impact on VOR gain, and it can be applied indifferently to all ages.ConclusionThese normative values permit the correlation between the results of any specific patient and the values of healthy people of the same age range.

Factors Affecting Sentence-in-Noise Recognition for Normal Hearing Listeners and Listeners with Hearing Loss.

Background and ObjectivesDespite amplified speech, listeners with hearing loss often report more difficulties understanding speech in background noise compared to normalhearing listeners. Various factors such as deteriorated hearing sensitivity, age, suprathreshold temporal resolution, and reduced capacity of working memory and attention can attribute to their sentence-in-noise problems. The present study aims to determine a primary explanatory factor for sentence-in-noise recognition difficulties in adults with or without hearing loss.Subjects and MethodsForty normal-hearing (NH) listeners (23-73 years) and thirty-four hearing-impaired (HI) listeners (24-80 years) participated for experimental testing. For both NH and HI group, the younger, middle-aged, older listeners were included. The sentence recognition score in noise was measured at 0 dB signal-to-noise ratio. The ability of temporal resolution was evaluated by gap detection performance using the Gaps-In-Noise test. Listeners’ short-term auditory working memory span was measured by forward and backward digit spans.ResultsOverall, the HI listeners’ sentence-in-noise recognition, temporal resolution abilities, and digit forward and backward spans were poorer compared to the NH listeners. Both NH and HI listeners had a substantial variability in performance. For NH listeners, only the digit backward span explained a small proportion of the variance in their sentence-in-noise performance. For the HI listeners, all the performance was influenced by age, and their sentence-in-noise difficulties were associated with various factors such as high-frequency hearing sensitivity, suprathreshold temporal resolution abilities, and working memory span. For the HI listeners, the critical predictors of the sentence-in-noise performance were composite measures of peripheral hearing sensitivity and suprathreshold temporal resolution abilities.ConclusionsThe primary explanatory factors for the sentence-in-noise recognition performance differ between NH and HI listeners. Factors affecting sentence-in-noise recognition performance differed between NH and HI listeners. The working memory was the primary predictor of the sentence-in-noise scores for the NH individuals. In contrast, a combination of factors seemed to contributed to speech-in-noise understanding for the HI listeners. Given this, we must be careful not to generalize findings from the NH listeners to the HI individuals.

Audiological findings in children with ataxia-telangiectasia (A-T) syndrome

AimTo assess peripheral and central hearing in children with A-T. Method3 children diagnosed with A-T according to the diagnostic criteria for A-T of the European Society for Immunodeficiencies. Involuntary movements were seen in the form of chorea-athetosis together with tremors. They were examined to assess both peripheral and central hearing was assessed (hearing thresholds). Sound-field testing, tympanometry, acoustic reflexes, Otoacoustic Emissions (OAEs) and Auditory Brainstem Responses (ABR) were done for all of them. ResultsBasic Audiological evaluation is of a limited value as the children are not co-operative. Sound field testing could not be done. Bilateral normal middle ear functions as reflected by Tympanometry and Acoustic Reflexes. Advanced Audiological evaluation including OAEs and ABR are more valuable in assessing hearing in children with A-T. Bilateral pass response at all test frequencies in DPOAEs. Abnormal ABR findings were obtained in the form of a delay in wave V latency more than 2 SD with subsequent increased in I-V interpeak latency with no significant interaural latency difference. ConclusionConsistent with bilateral normal peripheral hearing sensitivity with central hearing affection. LimitationsThe rarity of the disease, make it difficult to be applied on many cases.

Effects of aging on peripheral and central auditory processing in rats.

Hearing loss is a hallmark sign in the elderly population. Decline in auditory perception provokes deficits in the ability to localize sound sources and reduces speech perception, particularly in noise. In addition to a loss of peripheral hearing sensitivity, changes in more complex central structures have also been demonstrated. Related to these, this study examines the auditory directional maps in the deep layers of the superior colliculus of the rat. Hence, anesthetized Sprague-Dawley adult (10months) and aged (22months) rats underwent distortion product of otoacoustic emissions (DPOAEs) to assess cochlear function. Then, auditory brainstem responses (ABRs) were assessed, followed by extracellular single-unit recordings to determine age-related effects on central auditory functions. DPOAE amplitude levels were decreased in aged rats although they were still present between 3.0 and 24.0 kHz. ABR level thresholds in aged rats were significantly elevated at an early (cochlear nucleus - wave II) stage in the auditory brainstem. In the superior colliculus, thresholds were increased and the tuning widths of the directional receptive fields were significantly wider. Moreover, no systematic directional spatial arrangement was present among the neurons of the aged rats, implying that the topographical organization of the auditory directional map was abolished. These results suggest that the deterioration of the auditory directional spatial map can, to some extent, be attributable to age-related dysfunction at more central, perceptual stages of auditory processing.