Auditory brainstem response asymmetries in older adults: An exploratory study using click and speech stimuli.

BACKGROUND: Some evidence suggests that young adults exhibit a selective laterality of auditory brainstem response (ABR) elicited with speech stimuli. Little is known about such an auditory laterality in older adults. OBJECTIVE: The aim of this study was to investigate possible asymmetric auditory brainstem processing between right and left ear presentation in older adults. METHODS: Sixty-two older adults presenting with normal hearing thresholds according to their age and who were native speakers of Quebec French participated in this study. ABR was recorded using click and a 40-ms /da/ syllable. ABR was elicited through monaural right and monaural left stimulation. Latency and amplitude for click-and speech-ABR components were compared between right and left ear presentations. In addition, for the /da/ syllable, a fast Fourier transform analysis of the sustained frequency-following response (FFR) of the vowel was performed along with stimulus-to-response and right-left ear correlation analyses. RESULTS: No significant differences between right and left ear presentation were found for amplitudes and latencies of the click-ABR components. Significantly shorter latencies for right ear presentation as compared to left ear presentation were observed for onset and offset transient components (V, A and O), sustained components (D and E), and voiced transition components (C) of the speech-ABR. In addition, the spectral amplitude of the fundamental frequency (F0) was significantly larger for the left ear presentation than the right ear presentation. CONCLUSIONS: Results of this study show that older adults with normal hearing exhibit symmetric encoding for click stimuli at the brainstem level between the right and left ear presentation. However, they present with brainstem asymmetries for the encoding of selective stimulus components of the speech-ABR between the right and left ear presentation. The right ear presentation of a /da/ syllable elicited reduced neural timing for both transient and sustained components compared to the left ear. Conversely, a stronger left ear F0 encoding was observed. These findings suggest that at a preattentive, sensory stage of auditory processing, older adults lateralize speech stimuli similarly to young adults.

Association Between the Right Ear Advantage in Dichotic Listening and Interaural Differences in Sensory Processing at Lower Levels of the Auditory System in Older Adults.

OBJECTIVE: Current evidence suggests that an enhanced right ear advantage (REA) in dichotic listening (DL) among older adults may originate from age-related structural changes in the corpus callosum and age-related decline in cognitive processes. Less is known about the effect of information processing at lower portions of the auditory system on DL performance. The present study investigates whether interaural differences (ID) in sensory processing at lower levels of the auditory system are associated with the magnitude of the REA in DL among older adults. DESIGN: Sixty-eight older adults participated in the study. Participants were assessed with a DL test using nonforced (NF) and forced attention paradigms. Hearing sensitivity, transient-evoked otoacoustic emission (TEOAE), contralateral suppression of TEOAE, a proxy measure of medial olivocochlear activation, and auditory brainstem response to speech stimuli (speech-ABR) were tested in both ears separately. The ID in sensory processing at lower levels of the auditory system was derived by calculating the difference between the RE and LE for each auditory measure. Bivariate and multivariate regression models were performed. One multivariate model for each DL paradigm (NF and forced attention) was independently constructed. Measures of cognitive speed of processing and cognitive flexibility were accounted for in the regression models. RESULTS: For both multivariate regression models, ID in pure-tone thresholds and ID in MOC suppression of TEOAE were significantly associated with the magnitude of the REA for DL among older adults. Cognitive measures of speed of processing and cognitive flexibility also contributed to the magnitude of the REA. CONCLUSION: These results suggest that ID in sensory processing at lower levels of the auditory system account, at least in part, for the increased magnitude of the REA in DL among older adults.

Right-Ear Advantage for Unaided and Aided Speech Perception in Noise in Older Adults.

OBJECTIVE: To investigate whether the magnitude of the right-ear advantage (REA) for speech perception in noise decreased in aided conditions as compared with unaided conditions in older adults bilaterally fitted with hearing aids. A secondary aim was to determine the effect of audibility on the right- and left-ear processing for speech stimuli in both aided and unaided conditions. METHODS: Forty-two older adult, bilateral hearing-aid users were selected. Pure-tone audiometry and the hearing-in-noise test (HINT) were carried out and real-ear insertion gain (REIG) was measured in all participants. All HINT stimuli were delivered via loudspeakers in the free field in both aided and unaided conditions. RESULTS: Right-ear scores for HINT were significantly better than the left ear in both unaided and aided conditions. No significant differences in the magnitude of the REA between the unaided HINT and aided HINT scores were found. Regression models showed that audibility explained 47% and 53% of the variance in unaided HINT scores in the right and left ears, respectively. For the aided HINT scores, age and audibility explained 46% of the variability for the left-ear scores, while for the right ear, the only remaining significant variable in the model was REIG, which explained 12% of the right-ear HINT scores. CONCLUSION: Right-ear processing is significantly more efficient for speech stimuli in both unaided and aided conditions in older adults. Audibility affected unaided speech perception in right and left ears similarly however this was not the case in the aided condition. Audibility was associated with aided speech perception in noise in the left ear only.

Association between self-reported dizziness and asymmetric hearing loss in the older adults / Associação entre auto-referência de tontura e perda auditiva assimétrica no idoso

ABSTRACT Purpose: to verify the association between self-reported dizziness, degree and symmetry of hearing loss, age and gender in a sample of older adults. Methods: this retrospective study included the analysis of 440 records of older adults with a mean age of 72.9 years, enrolled from 2011 to 2015 in an auditory rehabilitation service. Binary logistic regression models were performed between the variables, and the data was analyzed using the SPSS 24.00 software. For all tests, alpha values were considered significant when lower than 0.05. Results: in the sample, 78 (17.7%) older adults had asymmetric hearing loss, and 27 (34.6%) of them complained of dizziness. Self-reported complaint of dizziness was significantly associated with female gender (p<0,001), to severe hearing loss (p<0,001), age under 70 years, and with asymmetric hearing loss(p<0,001). Conclusion: in this study, younger female elderlies with severe asymmetric hearing loss presented self-reported complaint of dizziness . These results suggest that this population should be routinely screened for balance problems in order to provide rehabilitation programs to avoid future falls.

RESUMO Objetivo: verificar a relação entre auto referência de tontura, o grau, a simetria da perda auditiva, idade e sexo, em idosos. Métodos: estudo retrospectivo que incluiu a análise de 440 registros de idosos com média de idade de 72,9 anos, cadastrados no período de 2011 a 2015 em um Serviço de Reabilitação Auditiva. Foram aplicados modelos de regressão logística binária entre as variáveis, os dados foram tabulados e processados pelo software SPSS 24.00. Para todos os testes, os valores de alfa foram considerados significantes quando menores que 0,05. Resultado: na amostra, 78 (17,7%) idosos apresentaram perda auditiva assimétrica, sendo que destes, 27 (34,6%) referiram queixa de tontura. A queixa de tontura apresentou relação estatisticamente significante com o sexo feminino (p<0,001), com o grau da perda auditiva severa (p<0,001), com a idade inferior a 70 anos (DP 8,6 anos) e com a assimetria da perda auditiva (p<0,001). Conclusão: no presente estudo, idosos do sexo feminino, mais jovens, com perda auditiva assimétrica e grau de perda auditiva severo apresentaram queixa auto referida de tontura. Estes resultados sugerem que essa população seja rotineiramente rastreada sobre problemas de equilíbrio, com o objetivo de fornecer programas de reabilitação, a fim de prevenir futuras quedas.