Relationship Between Distortion Product - Otoacoustic Emissions (DPOAEs) and High-Frequency Acoustic Immittance Measures.

BACKGROUND Pathologies that alter the impedance of the middle ear may consequently modify the DPOAE amplitude. The aim of this study was to correlate information from 2 different clinical procedures assessing middle ear status. Data from DPOAE responses (both DP-Gram and DP I/O functions) were correlated with data from multi-component tympanometry at 1000 Hz. MATERIAL AND METHODS The subjects were divided into a double-peak group (DPG) and a single-peak group (SPG) depending on 1000 Hz tympanogram pattern. Exclusion criteria (described in the Methods section) were applied to both groups and finally only 31 ears were assigned to each group. The subjects were also assessed with traditional tympanometry and behavioral audiometry. RESULTS Compared to the single-peak group, in terms of the 226 Hz tympanometry data, subjects in the DPG group presented: (i) higher values of ear canal volume; (ii) higher peak pressure, and (iii) significantly higher values of acoustic admittance. DPOAE amplitudes were lower in the DPG group only at 6006 Hz, but the difference in amplitude between the DPG and SPG groups decreased as the frequency increased. Statistical differences were observed only at 1001 Hz and a borderline difference at 1501 Hz. In terms of DPOAE I/O functions, significant differences were observed only in 4 of the 50 tested points. CONCLUSIONS The 1000-Hz tympanometric pattern significantly affects the structure of DPOAE responses only at 1001 Hz. In this context, changes in the properties of the middle ear (as detected by the 1000 Hz tympanometry) can be considered as prime candidates for the observed variability in the DP-grams and the DP I/O functions.

Correlation between DPOAE I/O functions and pure-tone thresholds.

UNLABELLED: Different studies have been carried out in order to correlate audiometric thresholds and distortion product otoacoustic emissions measurements (DPOAE). However, high variability and external interferences make hearing thresholds estimates by means of the DPOAE very little sensitive. The aim of this study was to check the correspondence between the pure tone thresholds and the cochlear response thresholds by DPOAE Input/output functions, considering the influence of the following variables: gender, past of acute otitis media, and ear side. METHOD: Prospective study comprehending 69 normal hearing individuals. Multiple mix regression models were applied to evaluate the correspondence between the two measurements studied. RESULTS: Statistically significant positive correlation was observed among all the frequencies compared (2000, 3000, 4000 e 6000 Hz). CONCLUSIONS: The 1 dB HL resolution pure tone thresholds and the above-mentioned variables had a direct impact on the high correlation between the measures studied, and it also reduced response variability. Nevertheless, response variability was still high, limiting the use of DPOAE I/O functions for hearing threshold estimates. We suggest that these variables should be considered for future studies with pure tone thresholds estimations by DPOAE I/O functions.

Correlação entre os limiares das curvas de crescimento das EOAPD e tons puros / Correlation between DPOAE I/O functions and pure-tone thresholds

Diversos estudos foram realizados com o objetivo de correlacionar limiares audiométricos e medidas de emissões otoacústicas - produtos de distorção (EOA-PD). Entretanto, a alta variabilidade e as interferências externas tornam a estimação dos limiares auditivos por meio das EOA-PD pouco sensível. O objetivo desse estudo foi verificar a correspondência entre os limiares audiométricos tonais e os limiares de respostas cocleares obtidos por meio das curvas de crescimento das EOA-PD (CCEOA-PD), considerando a influência das variáveis: sexo, antecedentes de otite média aguda e orelha direita e esquerda. CASUÍSTICA E MÉTODO: Estudo prospectivo envolvendo 69 indivíduos com audição normal. Modelos de regressão múltipla mistos foram utilizados para avaliação da correspondência entre as duas medidas estudadas. RESULTADOS: Houve correlação positiva e estatisticamente significante em todas as frequências comparadas. CONCLUSÕES: A pesquisa dos limiares audiométricos com resolução de 01 dBNA e a consideração das variáveis citadas contribuíram diretamente para a alta correlação entre as medidas estudadas, além de reduzir a variabilidade das respostas. Por outro lado, a variabilidade das respostas ainda foi alta, limitando a aplicação das CCEOA-PD para esse fim. Sugerimos que essas variáveis devam ser consideradas nos estudos futuros de estimação dos limiares por meio das CCEOA-PD.

Different studies have been carried out in order to correlate audiometric thresholds and distortion product otoacoustic emissions measurements (DPOAE). However, high variability and external interferences make hearing thresholds estimates by means of the DPOAE very little sensitive. The aim of this study was to check the correspondence between the pure tone thresholds and the cochlear response thresholds by DPOAE Input/output functions, considering the influence of the following variables: gender, past of acute otitis media, and ear side. METHOD: Prospective study comprehending 69 normal hearing individuals. Multiple mix regression models were applied to evaluate the correspondence between the two measurements studied. RESULTS: Statistically significant positive correlation was observed among all the frequencies compared (2000, 3000, 4000 e 6000 Hz). CONCLUSIONS: The 1dB HL resolution pure tone thresholds and the above-mentioned variables had a direct impact on the high correlation between the measures studied, and it also reduced response variability. Nevertheless, response variability was still high, limiting the use of DPOAE I/O functions for hearing threshold estimates. We suggest that these variables should be considered for future studies with pure tone thresholds estimations by DPOAE I/O functions.

Contralateral suppression of otoacoustic emissions: input-output functions in neonates.

BACKGROUND: The literature suggests that contralateral acoustic stimulation (CAS) alters the amplitude of the distortion product otoacoustic emissions (DPOAEs), but it is still unknown whether the DPOAE Input/Output (I/O) functions are also affected. To elucidate this aspect of the DPOAEs, the present study assessed the effects of CAS on DPOAE I/O functions at the frequencies of 2 kHz and 4 kHz, in a sample of term neonatal subjects. MATERIAL/METHODS: Sixty randomly selected neonates were included in the study. The DPOAE I/O functions were obtained at 2 kHz and 4 kHz, in the presence of a 60 dB SPL broad band-contralateral white noise, using the TDH39 headphones contralaterally. DPOAEs were recorded up to a stimulus level of L2 = 35 dB peSPL. RESULTS: Significant DPOAE amplitude suppression effects were observed at various L2 stimulus levels for both tested frequencies at 2 and 4 kHz. In contrast, the corresponding DPOAE slopes showed various alterations that were not statistically significant. CONCLUSIONS: The data from the present study show that contralateral acoustic stimulation significantly affects only the amplitude of the DPOAE I/O functions; the slope is affected, but not significantly. This observation can shed light on the nature of CAS, suggesting that the latter is primarily a linear phenomenon without the cochlear compression and non-linear components seen in the healthy cochlea. From the available data it is not possible to infer whether the sample size has influenced the obtained results and the study should be repeated with a larger sample size and assessing more frequencies.

Função da orelha média e das curvas de crescimento nas respostas das emissões otoacústicas / Middle-ear and growth functions on the responses of the otoacoustic emissions

INTRODUÇÃO: Dentre as medidas da função coclear, a curva de crescimento das Emissões Otoacústicas por produto de distorção (CCEOA PD) permite o registro da amplitude da emissão em função do crescimento sistemático nos níveis de tons primários. A CCEOA PD fornece parâmetros específicos sobre o limiar e o comportamento não-linear das EOA PD, porém a variabilidade das respostas inter e intrasujeitos reduz a confiabilidade dessa medida na avaliação da robustez das respostas cocleares e a relação dessa robustez com os limiares auditivos. OBJETIVOS: Esta pesquisa estudou as interações entre as medidas timpanométricas da orelha média e as medidas de função coclear em adultos jovens sem queixas auditivas, de acordo com as variáveis: antecedentes de alterações de orelha média, sexo e orelha direita / esquerda. MÉTODOS: Participaram 69 indivíduos com audição normal e idades entre 18 e 34 anos, sendo 21 homens e 48 mulheres. A caracterização das condições de orelha média foi obtida pela anamnese, com a informação dos antecedentes de alterações de orelha média e pela timpanometria com sondas de admitância de 226 e 1000 Hz. A audiometria foi realizada com resolução de 01 dB NA, o que possibilitou comparações mais refinadas entre o limiar psicoacústico da audiometria tonal, a amplitude do DP-Gram e os limiares das CCEOA PD. Além dessas variáveis, a interferência dos fatores sexo e orelha foram testadas em todas as análises. RESULTADOS/DISCUSSÃO: Os resultados apontaram que as curvas de crescimento sofreram influência significativa das variáveis sexo, antecedentes de alterações de orelha média e orelha direita / esquerda, porém, apenas a interferência dos antecedentes foi constante e causou um padrão de modificação, ou seja, o grupo com antecedentes apresentou respostas aquém das respostas do grupo sem antecedentes. Os limiares audiométricos também apresentaram alta correlação com as amplitudes...

INTRODUCTION: The Distortion Product Otoacoustic Emissions Input/Output function (DPOAE I/O function) is a subdivision of DPOAE, where the response amplitude is recorded such as a systematic growth function in the primary tones. The DPOAE I/O function provides specific parameters about the DPOAEs threshold and non-linearity. However, the response variability reduces the measure reliability to evaluate the cochlear robustness and the relationship between robustness and hearing thresholds. OBJECTIVE: This research studied the interaction between the tympanometric measures and cochlear functions measures in young adults without hearing complaints, considering the variables: middle-ear alteration antecedents, gender and right / left ear. METHODS: 69 normal hearing subjects, aged from 18 to 34 years participated of the study. From the total, 21 were men and 48 women. To reach the proposed objectives, the middle ear conditions were assessed by anamneses and 226 and 1000 Hz admittance probe-tone tympanometry. The audiometric thresholds were searched with 01 dBHL resolution to enable refined comparisons among pure-tone audiometry and DP-Gram amplitude and DPOAE I/O function thresholds. The gender and ear interference were also evaluated in all analyses. RESULTS/DISCUSSION: The results showed that the variables gender, antecedents and ear affected the I/O functions responses, but only the middle-ear alterations antecedents presented a constant modification pattern. In other words, the group with antecedents presented mainly reduced responses in comparison with no antecedents group. The audiometric thresholds also presented high correlation with DPOAE amplitudes and DPOAE I/O functions thresholds, after the detection of the variables affecting the results. As the background noise was controlled during this study, the results confirmed the importance of monitoring these variables in the normal hearing group compositions...

Latência das EOAPD em milissegundos e número de ondas / Latency of DPOAE in milliseconds and waves

As latências das Emissões Otoacústicas por Produto de Distorção são definidas como o intervalo de tempo que a onda parte de seu estímulo inicial e retorna para o meato acústico externo. Objetivo: O objetivo desta pesquisa foi verificar a latência das emissões otoacústicas por Produto de Distorção em adultos sem alterações auditivas, analisando a influência do gênero, orelha e freqüências. Forma de estudo: clínico prospectivo. Material e método: Foram usados as unidades de medida milissegundos e número de ondas. Foi um estudo experimental, realizado na cidade de São Paulo em 2003, com casuística de 38 adultos, sendo 18 homens e 20 mulheres normo-ouvintes. Não foi observada diferença entre orelhas, gênero e unidades de medida em relação à latência em milissegundos e número de ondas. Comparando as medidas milissegundos e número de ondas, foi observada uma alta correlação entre as duas formas de medida das latências. Foi concluído que a latência das Emissões Otoacústicas por Produto de Distorção diminui conforme se aumenta a freqüência em milissegundos e o contrário ocorre em número de ondas. Não foram observadas diferenças nas medidas de latência de Emissões Otoacústicas por Produto de Distorção entre gêneros, orelhas e unidades de medida.

The latency of Distortion Product Otoacoustic Emissions is defined as the time interval between the wave onset from initial stimulation and the return to the ear canal. Aim: The aim of this research was to verify the latency of the distortion product otoacoustic emissions in normal hearing adults, analyzing the influence of the gender, ear, frequencies and measurements. Study design: clinical prospective. Material and method: The measurements had been taken in milliseconds and waves. It was an experimental study, conducted at São Paulo City in 2003. The sample consisted of 38 adults, 18 men and 20 women. Significant Differences for interactions between frequency, ear, gender and measurements were not observed in relation to the latency in milliseconds and waves. A high correlation between the latency measurements in milliseconds and waves was observed. It was concluded that the latency of distortion product otoacoustic emission diminishes as increases the frequency in milliseconds and the opposite occurs in waves. Statistical differences in latencies of distortion product otoacoustic emission were not observed between gender, ears and measurements.