Spectrotemporal window of binaural integration in auditory object formation.

Binaural integration of interaural temporal information is essential for sound source localization and segregation. Current models of binaural interaction have shown that accurate sound localization in the horizontal plane depends on the resolution of phase ambiguous information by across-frequency integration. However, as such models are mostly static, it is not clear how proximate in time binaural events in different frequency channels should occur to form an auditory object with a unique lateral position. The present study examined the spectrotemporal window required for effective integration of binaural cues across frequency to form the perception of a stationary position. In Experiment 1, listeners judged whether dichotic frequency-modulated (FM) sweeps with a constant large nominal interaural delay (1500 µs), whose perceived laterality was ambiguous depending on the sweep rate (1500, 3000, 6000, and 12,000 Hz/s), produced a percept of continuous motion or a stationary image. Motion detection performance, indexed by d-prime (d') values, showed a clear effect of sweep rate, with auditory motion effects most pronounced for low sweep rates, and a punctate stationary image at high rates. Experiment 2 examined the effect of modulation rate (0.5, 3, 20, and 50 Hz) on lateralizing sinusoidally frequency-modulated (SFM) tones to confirm the effect of sweep rate on motion detection, independent of signal duration. Lateralization accuracy increased with increasing modulation rate up to 20 Hz and saturated at 50 Hz, with poorest performance occurring below 3 Hz depending on modulator phase. Using the transition point where percepts changed from motion to stationary images, we estimated a spectrotemporal integration window of approximately 150 ms per octave required for effective integration of interaural temporal cues across frequency channels. A Monte Carlo simulation based on a cross-correlation model of binaural interaction predicted 90% of the variance on perceptual motion detection performance as a function of FM sweep rate. Findings suggest that the rate of frequency channel convergence of binaural cues is essential to binaural lateralization.

Masking Level Difference in schoolchildren: environmental analysis. / Masking Level Difference em escolares: análises ambientais.

PURPOSE: To investigate the auditory ability of selective attention in the school population and to identify reference values to the age group from seven to ten years old through the Masking Level Difference Test, and to identify if the parents' schooling, as well as the family income can influence the test results. METHODS: Thirty-one schoolchildren who match the eligibility criteria attended the study, being 20 female and 11 male. An anamnesis was conducted to question the familiar income and the schooling of the children´s parents; we also performed visual inspection of the External Acoustic Meatus, Pure Tone Audiometry, Speech Audiometry, Acoustic Immittance Measures, Dichotic Digits Test and Masking Level Difference test. RESULTS: The mean age of the individuals was 8.67 years. There were no observed differences between genders and between the evaluated ages in the MLD performance. There was no relation between the parents' schooling and the average monthly income with the performance of the children in MLD Test. The MLD mean was 7.65 dB and standard deviation of 2.51 dB. CONCLUSION: The Masking Level Difference in schoolchildren from seven to ten years old is 7.65 dB and is independent of the gender, parents' schooling and the average monthly income of the schoolchild.

OBJETIVO: Pesquisar a habilidade auditiva de atenção seletiva na população escolar e identificar valores de referência para a faixa etária de sete a dez anos por meio do teste Masking Level Difference, além de identificar se a escolaridade dos pais, bem como a renda familiar, pode influenciar os resultados do teste. MÉTODO: Participaram do estudo 31 escolares que se encaixaram nos critérios de elegibilidade da pesquisa, sendo 20 do gênero feminino e 11 do gênero masculino. Realizou-se anamnese para questionamento da renda familiar e escolaridade dos pais do escolar, inspeção visual do meato acústico externo, audiometria tonal liminar, logoaudiometria, medidas de imitância acústica, teste Dicótico de Dígitos e teste Masking Level Difference. RESULTADOS: A idade média dos indivíduos foi de 8,67 anos. Não foi observada diferença entre os gêneros e entre as idades avaliadas, no desempenho do MLD. Não houve relação entre a escolaridade dos pais e a renda mensal média com o desempenho das crianças no MLD. A média do MLD foi de 7,65 dB, com desvio padrão de 2,51 dB. CONCLUSÃO: O Masking Level Difference em escolares de sete a dez anos é de 7,65 dB e independe do gênero, do nível de escolaridade dos pais ou da renda mensal média da família do escolar.

Masking Level Difference em escolares: análises ambientais / Masking Level Difference in schoolchildren: environmental analysis

RESUMO Objetivo Pesquisar a habilidade auditiva de atenção seletiva na população escolar e identificar valores de referência para a faixa etária de sete a dez anos por meio do teste Masking Level Difference, além de identificar se a escolaridade dos pais, bem como a renda familiar, pode influenciar os resultados do teste. Método Participaram do estudo 31 escolares que se encaixaram nos critérios de elegibilidade da pesquisa, sendo 20 do gênero feminino e 11 do gênero masculino. Realizou-se anamnese para questionamento da renda familiar e escolaridade dos pais do escolar, inspeção visual do meato acústico externo, audiometria tonal liminar, logoaudiometria, medidas de imitância acústica, teste Dicótico de Dígitos e teste Masking Level Difference. Resultados A idade média dos indivíduos foi de 8,67 anos. Não foi observada diferença entre os gêneros e entre as idades avaliadas, no desempenho do MLD. Não houve relação entre a escolaridade dos pais e a renda mensal média com o desempenho das crianças no MLD. A média do MLD foi de 7,65 dB, com desvio padrão de 2,51 dB. Conclusão O Masking Level Difference em escolares de sete a dez anos é de 7,65 dB e independe do gênero, do nível de escolaridade dos pais ou da renda mensal média da família do escolar.

ABSTRACT Purpose To investigate the auditory ability of selective attention in the school population and to identify reference values to the age group from seven to ten years old through the Masking Level Difference Test, and to identify if the parents' schooling, as well as the family income can influence the test results. Methods Thirty-one schoolchildren who match the eligibility criteria attended the study, being 20 female and 11 male. An anamnesis was conducted to question the familiar income and the schooling of the children´s parents; we also performed visual inspection of the External Acoustic Meatus, Pure Tone Audiometry, Speech Audiometry, Acoustic Immittance Measures, Dichotic Digits Test and Masking Level Difference test. Results The mean age of the individuals was 8.67 years. There were no observed differences between genders and between the evaluated ages in the MLD performance. There was no relation between the parents' schooling and the average monthly income with the performance of the children in MLD Test. The MLD mean was 7.65 dB and standard deviation of 2.51 dB. Conclusion The Masking Level Difference in schoolchildren from seven to ten years old is 7.65 dB and is independent of the gender, parents' schooling and the average monthly income of the schoolchild.

An assessment of the direction-finding accuracy of bat biosonar beampatterns.

In the biosonar systems of bats, emitted acoustic energy and receiver sensitivity are distributed over direction and frequency through beampattern functions that have diverse and often complicated geometries. This complexity could be used by the animals to determine the direction of incoming sounds based on spectral signatures. The present study has investigated how well bat biosonar beampatterns are suited for direction finding using a measure of the smallest estimator variance that is possible for a given direction [Cramér-Rao lower bound (CRLB)]. CRLB values were estimated for numerical beampattern estimates derived from 330 individual shape samples, 157 noseleaves (used for emission), and 173 outer ears (pinnae). At an assumed 60 dB signal-to-noise ratio, the average value of the CRLB was 3.9°, which is similar to previous behavioral findings. Distribution for the CRLBs in individual beampatterns had a positive skew indicating the existence of regions where a given beampattern does not support a high accuracy. The highest supported accuracies were for direction finding in elevation (with the exception of phyllostomid emission patterns). No large, obvious differences in the CRLB (greater 2° in the mean) were found between the investigated major taxonomic groups, suggesting that different bat species have access to similar direction-finding information.

The cat's meow: A high-field fMRI assessment of cortical activity in response to vocalizations and complex auditory stimuli.

Sensory systems are typically constructed in a hierarchical fashion such that lower level subcortical and cortical areas process basic stimulus features, while higher level areas reassemble these features into object-level representations. A number of anatomical pathway tracing studies have suggested that the auditory cortical hierarchy of the cat extends from a core region, consisting of the primary auditory cortex (A1) and the anterior auditory field (AAF), to higher level auditory fields that are located ventrally. Unfortunately, limitations on electrophysiological examination of these higher level fields have resulted in an incomplete understanding of the functional organization of the auditory cortex. Thus, the current study uses functional MRI in conjunction with a variety of simple and complex auditory stimuli to provide the first comprehensive examination of function across the entire cortical hierarchy. Auditory cortex function is shown to be largely lateralized to the left hemisphere, and is concentrated bilaterally in fields surrounding the posterior ectosylvian sulcus. The use of narrowband noise stimuli enables the visualization of tonotopic gradients in the posterior auditory field (PAF) and ventral posterior auditory field (VPAF) that have previously been unverifiable using fMRI and pure tones. Furthermore, auditory fields that are inaccessible to more invasive techniques, such as the insular (IN) and temporal (T) cortices, are shown to be selectively responsive to vocalizations. Collectively, these data provide a much needed functional correlate for anatomical examinations of the hierarchy of cortical structures within the cat auditory cortex.

Music enrichment programs improve the neural encoding of speech in at-risk children.

Musicians are often reported to have enhanced neurophysiological functions, especially in the auditory system. Musical training is thought to improve nervous system function by focusing attention on meaningful acoustic cues, and these improvements in auditory processing cascade to language and cognitive skills. Correlational studies have reported musician enhancements in a variety of populations across the life span. In light of these reports, educators are considering the potential for co-curricular music programs to provide auditory-cognitive enrichment to children during critical developmental years. To date, however, no studies have evaluated biological changes following participation in existing, successful music education programs. We used a randomized control design to investigate whether community music participation induces a tangible change in auditory processing. The community music training was a longstanding and successful program that provides free music instruction to children from underserved backgrounds who stand at high risk for learning and social problems. Children who completed 2 years of music training had a stronger neurophysiological distinction of stop consonants, a neural mechanism linked to reading and language skills. One year of training was insufficient to elicit changes in nervous system function; beyond 1 year, however, greater amounts of instrumental music training were associated with larger gains in neural processing. We therefore provide the first direct evidence that community music programs enhance the neural processing of speech in at-risk children, suggesting that active and repeated engagement with sound changes neural function.

Auditory processing in children and adolescents in situations of risk and vulnerability.

CONTEXT AND OBJECTIVE: Children and adolescents who live in situations of social vulnerability present a series of health problems. Nonetheless, affirmations that sensory and cognitive abnormalities are present are a matter of controversy. The aim of this study was to investigate aspects to auditory processing, through applying the brainstem auditory evoked potential (BAEP) and behavioral auditory processing tests to children living on the streets, and comparison with a control group. DESIGN AND SETTING: Cross-sectional study in the Laboratory of Auditory Processing, School of Medicine, Universidade de São Paulo. METHODS: The auditory processing tests were applied to a group of 27 individuals, subdivided into 11 children (7 to 10 years old) and 16 adolescents (11 to 16 years old), of both sexes, in situations of social vulnerability, compared with an age-matched control group of 10 children and 11 adolescents without complaints. The BAEP test was also applied to investigate the integrity of the auditory pathway. RESULTS: For both children and adolescents, there were significant differences between the study and control groups in most of the tests applied, with significantly worse performance in the study group, except in the pediatric speech intelligibility test. Only one child had an abnormal result in the BAEP test. CONCLUSIONS: The results showed that the study group (children and adolescents) presented poor performance in the behavioral auditory processing tests, despite their unaltered auditory brainstem pathways, as shown by their normal results in the BAEP test.

Auditory processing in children and adolescents in situations of risk and vulnerability / Processamento auditivo em crianças e adolescentes em situação de risco e vulnerabilidade

CONTEXT AND OBJECTIVE: Children and adolescents who live in situations of social vulnerability present a series of health problems. Nonetheless, affirmations that sensory and cognitive abnormalities are present are a matter of controversy. The aim of this study was to investigate aspects to auditory processing, through applying the brainstem auditory evoked potential (BAEP) and behavioral auditory processing tests to children living on the streets, and comparison with a control group. DESIGN AND SETTING: Cross-sectional study in the Laboratory of Auditory Processing, School of Medicine, Universidade de São Paulo. METHODS: The auditory processing tests were applied to a group of 27 individuals, subdivided into 11 children (7 to 10 years old) and 16 adolescents (11 to 16 years old), of both sexes, in situations of social vulnerability, compared with an age-matched control group of 10 children and 11 adolescents without complaints. The BAEP test was also applied to investigate the integrity of the auditory pathway. RESULTS: For both children and adolescents, there were significant differences between the study and control groups in most of the tests applied, with significantly worse performance in the study group, except in the pediatric speech intelligibility test. Only one child had an abnormal result in the BAEP test. CONCLUSIONS: The results showed that the study group (children and adolescents) presented poor performance in the behavioral auditory processing tests, despite their unaltered auditory brainstem pathways, as shown by their normal results in the BAEP test.

CONTEXTO E OBJETIVO: Crianças e adolescentes que vivem em situação de vulnerabilidade social apresentam uma série de problemas de saúde. Apesar disso, ainda é controversa a afirmação sobre a existência de alterações cognitivas e/ou sensoriais. O objetivo deste estudo foi investigar aspectos relacionados ao processamento auditivo, através da aplicação de testes de potencial evocado auditivo de tronco encefálico (PEATE) e avaliação comportamental do processamento auditivo em crianças em situação de rua, comparando a um grupo controle. TIPO DE ESTUDO E LOCAL: Estudo transversal no Laboratório de Processamento Auditivo, Faculdade de Medicina da Universidade de São Paulo. MÉTODOS: Os testes de processamento auditivo foram aplicados em um grupo de 27 indivíduos, subdivididos em grupos de 11 crianças (7 a 10 anos) e 16 adolescentes (11 a 16 anos) de ambos os sexos, em situação de vulnerabilidade social, e comparado a um grupo controle, formado por 21 crianças, subdivididas em grupos de 10 crianças e 11 adolescentes, pareados por idade, sem queixas. Também se aplicou os PEATE para investigação da integridade da via auditiva. RESULTADOS: Para ambas as faixas etárias, foram encontradas diferenças significantes entre grupos estudo e controle para a maioria dos testes aplicados, sendo que o grupo estudo apresentou desempenho estatisticamente pior do que o controle para todos os testes, exceto para o teste pediatric speech intelligibility. Apenas uma criança apresentou resultado alterado para os PEATE. CONCLUSÕES: Os resultados demonstraram pior desempenho do grupo estudo (crianças e adolescentes) para os testes comportamentais de processamento auditivo, apesar de estes apresentarem integridade da via auditiva em nível de tronco encefálico, demonstrada pela normalidade nos resultados do PEATE.

Concert hall acoustics assessment with individually elicited attributes.

Concert hall acoustics was evaluated with a descriptive sensory analysis method by employing an individual vocabulary development technique. The goal was to obtain sensory profiles of three concert halls by eliciting perceptual attributes for evaluation and comparison of the halls. The stimuli were gathered by playing back anechoic symphony music from 34 loudspeakers on stage in each concert hall and recording the sound field with a microphone array. Four musical programs were processed for multichannel 3D sound reproduction in the actual listening test. Twenty screened assessors developed their individual set of attributes and performed a comparative evaluation of nine seats, three in each hall. The results contain the distinctive groups of elicited attributes and show good agreement within assessors, even though they applied individual attributes when rating the samples. It was also found that loudness and distance gave the strongest perceptual direction to the principal component basis. In addition, the study revealed that the perception of reverberance is related to the size of the space or to the enveloping reverberance, depending on the assessor.

[Central auditory processes evaluated with psychoacoustic tests in normal children]. / Evaluación de procesos centrales de la audición con pruebas psicoacústicas en niños normales.

OBJECTIVE: To identify the natural tendencies of hits and calculate the cutoff for a test group of central auditory processes (CAP): binaural fusion, filtered words, dichotic digits, frequency patterns and duration patterns and ambient sounds in normal 5-, 7-, 9- and 11-year-old children. MATERIAL AND METHODS: We studied 369 children (738 ears) who attend public schools in Puebla City, administering 6 CAP tests (two binaural and four monaural); we used an audiometer at 50dB SL re-threshold at 1 kHz, from a CD recorded at the CCECADET-UNAM-INR (Centre for Applied Science and Technological Development at the National Autonomous University of Mexico and the National Institute for Rehabilitation). RESULTS: We determined the cutoff points for the six tests. CONCLUSION: This information represents an advance in the normative standards in the field of psychoacoustic tests for CAP in Spanish and in the socio-educational context prevalent in Mexico. It is important to evaluate these results against CAP disorders.

Assessment of temporal state-dependent interactions between auditory fMRI responses to desired and undesired acoustic sources.

A confounding factor in auditory functional magnetic resonance imaging (fMRI) experiments is the presence of the acoustic noise inherently associated with the echo planar imaging acquisition technique. Previous studies have demonstrated that this noise can induce unwanted neuronal responses that can mask stimulus-induced responses. Similarly, activation accumulated over multiple stimuli has been demonstrated to elevate the baseline, thus reducing the dynamic range available for subsequent responses. To best evaluate responses to auditory stimuli, it is necessary to account for the presence of all recent acoustic stimulation, beginning with an understanding of the attenuating effects brought about by interaction between and among induced unwanted neuronal responses, and responses to desired auditory stimuli. This study focuses on the characterization of the duration of this temporal memory and qualitative assessment of the associated response attenuation. Two experimental parameters--inter-stimulus interval (ISI) and repetition time (TR)--were varied during an fMRI experiment in which participants were asked to passively attend to an auditory stimulus. Results present evidence of a state-dependent interaction between induced responses. As expected, attenuating effects of these interactions become less significant as TR and ISI increase and in contrast to previous work, persist up to 18s after a stimulus presentation.

Lateralization produced by envelope-based interaural temporal disparities of high-frequency, raised-sine stimuli: empirical data and modeling.

An acoustic pointing task was used to measure extents of laterality produced by ongoing interaural temporal disparities (ITDs) conveyed by the envelopes of 4-kHz-centered raised-sine stimuli while varying, parametrically, their peakedness, depth of modulation, and frequency of modulation. One purpose of the study was to determine whether such manipulations would produce changes in laterality logically consistent with those found for ITD-discrimination thresholds reported by Bernstein and Trahiotis [J. Acoust. Soc. Am. 125, 3234-3242 (2009)]. The data obtained revealed that they did in that (1) increasing depth of modulation, peakedness, or frequency of modulation between 32 and 128 Hz produced smaller threshold ITDs and greater laterality and (2) increasing frequency of modulation to 256 Hz produced modest increases in threshold ITDs and modest decreases in laterality. The extents of laterality measured were successfully accounted for via an augmentation of the cross-correlation-based "position-variable" modeling approach developed by Stern and Shear [J. Acoust. Soc. Am. 100, 2278-2288 (1996)] to account for ITD-based extents of laterality obtained at low spectral frequencies.

Lateralization produced by interaural intensitive disparities appears to be larger for high- vs low-frequency stimuli.

The purpose of this communication is to report the results of a study indicating that a given magnitude of interaural intensitive disparity (IID) produced a larger extent of laterality, as measured via an acoustic pointer, for stimuli centered at 4 kHz than for stimuli centered at 500 Hz. The data and their analysis, taken together, suggest that the findings reflect true across-frequency differences rather than being manifestations of response-related factors.

Recalibration of the auditory continuity illusion: sensory and decisional effects.

An interrupted sound can be perceived as continuous when noise masks the interruption, creating an illusion of continuity. Recent findings have shown that adaptor sounds preceding an ambiguous target sound can influence listeners' rating of target continuity. However, it remains unclear whether these aftereffects on perceived continuity influence sensory processes, decisional processes (i.e., criterion shifts), or both. The present study addressed this question. Results show that the target sound was more likely to be rated as 'continuous' when preceded by adaptors that were perceived as clearly discontinuous than when it was preceded by adaptors that were heard (illusorily or veridically) as continuous. Detection-theory analyses indicated that these contrastive aftereffects reflect a combination of sensory and decisional processes. The contrastive sensory aftereffect persisted even when adaptors and targets were presented to opposite ears, suggesting a neural origin in structures that receive binaural inputs. Finally, physically identical but perceptually ambiguous adaptors that were rated as 'continuous' induced more reports of target continuity than adaptors that were rated as 'discontinuous'. This assimilative aftereffect was purely decisional. These findings confirm that judgments of auditory continuity can be influenced by preceding events, and reveal that these aftereffects have both sensory and decisional components.

Accounting quantitatively for sensitivity to envelope-based interaural temporal disparities at high frequencies.

Bernstein and Trahiotis [(2009). J. Acoust. Soc. Am. 125, 3234-3242] reported threshold interaural temporal disparities (ITDs) conveyed by the envelopes of 4-kHz-centered "raised-sine" stimuli. A raised-sine stimulus consists of a carrier modulated by a sinusoid raised to an exponent. Such stimuli permitted Bernstein and Trahiotis to vary, independently, stimulus modulation frequency, modulation depth, and "relative peakedness/deadtime." An interaural correlation-based model that included stages mimicking peripheral auditory processing captured most of the data save for an overestimation of threshold ITDs obtained when the depth of modulation was 25% and the raised-sine exponent was 8.0. The purpose of the present study was: (1) to present a quantitative evaluation of how well other measures, including normalized envelope fourth moment, envelope peakwidth, and envelope "deadtime" might also account for the data reported by Bernstein and Trahiotis and (2) to present new threshold ITDs measured while varying, factorially, depth of modulation, raised-sine exponent, and modulation frequency. Quantitative analyses of both the prior and the new data showed that the normalized interaural correlation, computed subsequent to peripheral auditory processing, provided the most accurate predictions. Importantly, the overestimation of threshold ITDs did not occur when it was assumed that listeners can employ information within "off-frequency" auditory filters.

Cochlear implants and spoken language processing abilities: review and assessment of the literature.

Cochlear implants (CIs) process sounds electronically and then transmit electric stimulation to the cochlea of individuals with sensorineural deafness, restoring some sensation of auditory perception. Many congenitally deaf CI recipients achieve a high degree of accuracy in speech perception and develop near-normal language skills. Post-lingually deafened implant recipients often regain the ability to understand and use spoken language with or without the aid of visual input (i.e. lip reading). However, there is wide variation in individual outcomes following cochlear implantation, and some CI recipients never develop useable speech and oral language skills. The causes of this enormous variation in outcomes are only partly understood at the present time. The variables most strongly associated with language outcomes are age at implantation and mode of communication in rehabilitation. Thus, some of the more important factors determining success of cochlear implantation are broadly related to neural plasticity that appears to be transiently present in deaf individuals. In this article we review the expected outcomes of cochlear implantation, potential predictors of those outcomes, the basic science regarding critical and sensitive periods, and several new research directions in the field of cochlear implantation.

Modeling the temporal dynamics of distinctive feature landmark detectors for speech recognition.

This paper elaborates on a computational model for speech recognition that is inspired by several interrelated strands of research in phonology, acoustic phonetics, speech perception, and neuroscience. The goals are twofold: (i) to explore frameworks for recognition that may provide a viable alternative to the current hidden Markov model (HMM) based speech recognition systems and (ii) to provide a computational platform that will facilitate engaging, quantifying, and testing various theories in the scientific traditions in phonetics, psychology, and neuroscience. This motivation leads to an approach that constructs a hierarchically structured point process representation based on distinctive feature landmark detectors and probabilistically integrates the firing patterns of these detectors to decode a phonological sequence. The accuracy of a broad class recognizer based on this framework is competitive with equivalent HMM-based systems. Various avenues for future development of the presented methodology are outlined.

Avaliação do processamento auditivo em idosos que relatam ouvir bem / Auditory processing assessment in older people with no report of hearing disability

Em idosos, os resultados da avaliação comportamental das vias auditivas centrais são considerados de difícil interpretação devido à possível interferência do comprometimento das vias auditivas periféricas. OBJETIVO: Avaliar a eficiência das funções auditivas centrais de idosos que relatam ouvir bem. MATERIAL E MÉTODO: Estudo de casos que incluiu 40 indivíduos na faixa etária de 60 a 75 anos. Os pacientes foram submetidos à avaliação do processamento auditivo que constou de anamnese, exame otorrinolaringológico, audiometria tonal liminar, limiar de reconhecimento de fala, índice de reconhecimento de fala, imitanciometria, pesquisa de reflexos estapedianos, teste de identificação de sentenças sintéticas com mensagem competitiva ipsilateral, teste de padrões de freqüência e teste de dissílabos alternados por meio de tarefa dicótica. RESULTADOS: Gênero, faixa etária e perda auditiva não influenciaram os resultados dos testes de padrões de freqüência e dissílabos alternados por meio de tarefa dicótica; faixa etária e perda auditiva influenciaram os resultados do teste de identificação de sentenças com mensagem competitiva ipsilateral. Porcentagens de acertos abaixo dos padrões da normalidade de adultos foram observadas nos três testes que acessam as funções auditivas centrais. CONCLUSÃO: Indivíduos idosos que relatam ouvir bem apresentam prevalência relevante de sinais de ineficiência das funções auditivas centrais.

In the elderly, the results of central auditory pathways behavioral assessments are considered to be difficult to read because of the possible interference of peripheral auditory pathway involvement. AIM: Assess the efficacy of the central auditory function in elderly patients who do not complain of hearing. MATERIALS AND METHODS: Case study involving 40 individuals within the age range of 60 to 75 years. The patients underwent auditory processing evaluation based on anamnesis, otorhinolaryngological exam, threshold tonal audiometry, speech recognition threshold, speech recognition index, immittance measures, stapes reflex study, synthetic phrases identification test with ipsilateral competitive message, frequency pattern test and alternate twin-syllable test through dichotic task; age range and hearing loss influenced results from the phrases identification with ipsilateral competitive message. Percentages of right answers below normal standards were seen in the three tests that assessed the central auditory functions. CONCLUSION: Elderly individuals who did not complain of hearing presented relevant prevalence of signs of central auditory function inefficiencies.

Auditory processing assessment in older people with no report of hearing disability.

UNLABELLED: In the elderly, the results of central auditory pathways behavioral assessments are considered to be difficult to read because of the possible interference of peripheral auditory pathway involvement. AIM: Assess the efficacy of the central auditory function in elderly patients who do not complain of hearing. MATERIALS AND METHODS: Case study involving 40 individuals within the age range of 60 to 75 years. The patients underwent auditory processing evaluation based on anamnesis, otorhinolaryngological exam, threshold tonal audiometry, speech recognition threshold, speech recognition index, immittance measures, stapes reflex study, synthetic phrases identification test with ipsilateral competitive message, frequency pattern test and alternate twin-syllable test through dichotic task; age range and hearing loss influenced results from the phrases identification with ipsilateral competitive message. Percentages of right answers below normal standards were seen in the three tests that assessed the central auditory functions. CONCLUSION: Elderly individuals who did not complain of hearing presented relevant prevalence of signs of central auditory function inefficiencies.

Adaptation reduces spike-count reliability, but not spike-timing precision, of auditory nerve responses.

Sensory systems use adaptive coding mechanisms to filter redundant information from the environment to efficiently represent the external world. One such mechanism found in most sensory neurons is rate adaptation, defined as a reduction in firing rate in response to a constant stimulus. In auditory nerve, this form of adaptation is likely mediated by exhaustion of release-ready synaptic vesicles in the cochlear hair cell. To better understand how specific synaptic mechanisms limit neural coding strategies, we examined the trial-to-trial variability of auditory nerve responses during short-term rate-adaptation by measuring spike-timing precision and spike-count reliability. After adaptation, precision remained unchanged, whereas for all but the lowest-frequency fibers, reliability decreased. Modeling statistical properties of the hair cell-afferent fiber synapse suggested that the ability of one or a few vesicles to elicit an action potential reduces the inherent response variability expected from quantal neurotransmitter release, and thereby confers the observed count reliability at sound onset. However, with adaptation, depletion of the readily releasable pool of vesicles diminishes quantal content and antagonizes the postsynaptic enhancement of reliability. These findings imply that during the course of short-term adaptation, coding strategies that employ a rate code are constrained by increased neural noise because of vesicle depletion, whereas those that employ a temporal code are not.