Development of 90th Percentile Norms for Ipsilateral Acoustic Reflex Thresholds: A Feasibility Study

The acoustic reflex threshold has been well established in the literature as an involuntary bilateral contraction of the stapedius muscle in response to loud transient sounds. Additionally, the clinical utility of the acoustic reflex threshold has been established as it allows for the differential diagnosis of many different conductive, cochlear and retrocochlear pathologies. Gelfand, Schwander and Silman (1990) have established and validated 90th percentile normative data for use with the contralateral acoustic reflex threshold. Much of the literature on the acoustic reflex threshold has focused on the contralateral acoustic reflex threshold; however, surveys have found that many clinicians are performing the ipsilateral acoustic reflex threshold in lieu of either the contralateral reflex or both together. The purpose of this study was to determine the feasibility of establishing 90th percentile normative data for use with the ipsilateral acoustic reflex threshold in view of the lower maximum outputs. Results indicated that ipsilateral acoustic reflex thresholds were likely to be present for hearing losses through at least moderate levels and were likely to be absent at levels of 70 dB HL and above. Results of the current feasibility study indicate the need for a larger-scale exploration of the ipsilateral acoustic reflex threshold as a function of hearing loss with particular emphasis on the moderately severe range

Measures of Acoustic Reflexes in Typically Developing Children and Children with Suspected Auditory Processing Disorder

A series of studies were conducted to examine the acoustic reflex in normal hearing adults, typically developing children and children with suspected auditory processing disorder (APD). Elevated acoustic reflex thresholds (ART) and shallower acoustic reflex growth functions (ARGF) were found in children with suspected APD in comparison to typically developing children and normal hearing adults. These effects were strongest in the crossed condition. There were no group differences for acoustic reflex latency (ARL) or acoustic reflex decay (ARD). In all studies the children with suspected APD were divided into two groups based on the diagnosis made on the basis of a behavioral APD battery; (1) APD which included children who received APD diagnosis and (2) Clinical non-APD who did not receive APD diagnosis. Children in the clinical non-APD and APD groups had similar ART and ARGF abnormalities highlighting a potential weakness in relying strictly on behavioral tests in the assessment of children suspected of APD. The effect of acoustic reflex activation on middle ear absorbance (MEA) and middle ear resonant frequency (MERF) was also investigated. It was found that the activation of the acoustic reflex resulted in a decrease of MEA between 226 and 1000 Hz, an increase MEA between 1000 and 2000 Hz and shift of MERF to a higher frequency. These changes in middle ear function may be critical to speech in noise perception. The effect of reflex activation was diminished in children with suspected APD. Across studies, acoustic reflex measures including ART, ARGF and the effect of the reflex on MEA and MERF showed a trend suggesting age-related changes but the trends did not reach statistical significance. However, a significant developmental trend in ARTs was found when corrected for ear canal volume differences. These results suggest that acoustic reflex measures in clinical children should be compared with those of typically developing children rather adults

Acoustic Reflex Activation and its Effect on Middle Ear Function

Previous studies have suggested larger magnitudes and lower thresholds in ipsilateral acoustic reflexes when compared to contralateral acoustic reflexes. This pilot study explored these effects by measuring how sound is transmitted through the middle ear. Middle ear absorbance was measured in the ipsilateral and contralateral conditions with and without activation of the acoustic reflex in normal hearing adults. Data showed that ipsilateral acoustic reflex thresholds (ART) were approximately 5 dB lower than contralateral ARTs. The magnitude of the acoustic reflex was shown to be larger in the ipsilateral condition. Results suggest that there is an evident contrast between ipsilateral and contralateral absorbance values. When considering elevated or absent acoustic reflexes in children with auditory processing disorder (APD) and the role of the acoustic reflex on speech perception in the presence of noise, it is important to investigate this contrast with regards to current clinical diagnostic tests

Synthetic sentence identification (SSI) and contralateral acoustic stapedius reflex

BACKGROUND: the study of the relationship of the contralateral acoustic reflex with the auditory skill of closure. AIM: to analyze the identification of a speech signal in the presence of competitive sounds in subjects with absence of contralateral acoustic reflex. METHOD: application of the synthetic sentence identification (SSI) test under the conditions of competitive contralateral message (SSI-CCM), with the signal-to-noise ratio of 0 and -40dB, and ipsilateral competitive message (SSI-ICM), with the signal-to-noise ratio of 0, -10, -15 and -20dB, in 43 young adults (group A = 21 subjects with contralateral acoustic reflex present in all of the investigated frequencies, and group B = 22 subjects with contralateral reflex absent at the frequency of 500Hz, or in all of the investigated frequencies, or still in some of the investigated frequencies necessarily including 500Hz), of both gender, with no hearing, otologic or learning disabilities. RESULTS: the acoustic reflex threshold was above 100dB NA in 59% of the individuals in group B and in 14% of the individuals in group A. All subjects performed according to the normal pattern suggested in the specialized literature for the SSI test. The performance of group B in the SSI-ICM test was inferior to that of group A for all the signal-to-noise ratios used, although the difference was not statistically significant. Group B, which presented an acoustic reflex threshold higher than 100dB NA or the absence of the acoustic reflex, was also the group that presented the worse performance in the SSI test. CONCLUSION: the absence of the contralateral acoustic reflex seems to interfere in the identification of the speech signal in the presence of competitive noises.TEMA: estudo da relação do reflexo acústico contralateral na habilidade auditiva de fechamento auditivo. OBJETIVO: analisar a identificação do sinal de fala em presença de sons competitivos em sujeitos com ausência do reflexo acústico contralateral. MÉTODO: aplicação do teste de identificação de sentenças sintéticas (SSI) nas condições mensagem competitiva contralateral (SSI-MCC), na relação sinal-ruído de 0 e -40dB e mensagem competitiva ipsilateral (SSI-ICM), na relação sinal-ruído de 0, -10, -15 e -20dB, em 43 adultos-jovens (grupo A = 21 sujeitos com presença do reflexo acústico contralateral em todas as freqüências pesquisadas e grupo B = 22 sujeitos com ausência do reflexo na freqüência de 500Hz, em todas as freqüências pesquisadas ou ainda em algumas das freqüências pesquisadas, mas que incluísse 500Hz), de ambos os sexos sem queixas auditivas, otológicas ou de aprendizagem. RESULTADOS: o limiar do reflexo acústico esteve acima de 100dB NA em 59% dos indivíduos do grupo B e em 14% dos indivíduos do grupo A, todos os indivíduos apresentaram desempenho de acordo com o padrão de normalidade sugerido pela literatura especializada para o teste SSI, o desempenho do grupo B no teste SSI-ICM foi inferior ao grupo A em todas as relações sinal-ruído utilizadas, embora a diferença não tenha sido estatisticamente significante, o grupo B que apresentou limiar do reflexo acústico superior a 100dB NA ou ausência do reflexo acústico também foi o que apresentou pior desempenho no teste SSI. CONCLUSÃO: a ausência do reflexo acústico contralateral parece interferir na identificação do sinal de fala na presença de ruídos competitivos.Pontifícia Universidade Católica de São PauloUniversidade de São Paulo Faculdade de Medicina de Ribeirão Preto Departamento de Oftalmologia, Otorrinolaringologia e Cirurgia de Cabeça e PescoçoUniversidade Federal de São Paulo (UNIFESP)PUC-SP Departamento de Clínica FonoaudiológicaUNIFESPSciEL

Prediction of Hearing Thresholds by Means of the Acoustic Reflex with Autistic and Normal Subjects

This study concerns audiometric evaluation and prediction of hearing loss in the autistic child based on information derived from acoustic reflex thresholds. Two groups (autistic males and normal children) of five subjects each were utilized. Results indicated that the acoustic reflex method consistently predicted significantly higher hearing thresholds for autistic subjects than operant pure-tone audiometric procedures. Furthermore, the acoustic reflex thresholds were significantly less sensitive in the autistic group than in the normal group, suggesting that the acoustic reflex response is somehow altered in autistic individuals. These findings are consistent with earlier work which hypothesized that autistics, manifest an organic brain lesion which interferes with the propagation of auditory information

Evaluation of Acoustic Reflex and Reflex Decay Tests in Geriatric Group

Objective: To determine average acoustic reflex thresholds in geriatric groups by assessing ipsilateral and contralateral acoustic reflex and reflex decay tests.Methods: A total of 25 elders between ages 65-84 years (74.3±5.4) and 25 individuals between ages 18-45 years (30.4±4.2) were recruited for the study. After ear, nose, and throat examination, ipsilateral and contralateral acoustic reflex thresholds at 500, 1000, 2000, and 4000 Hertz (Hz) were determined and a reflex decay test at contralateral 500 Hz was conducted. Ipsilateral acoustic reflex thresholds were obtained with high-frequency band, low-frequency band, and wide band noise, and the results were compared with ipsilateral acoustic reflexes at 500, 1000, 2000, and 4000 Hz.Results: There was no statistically significant difference between the two groups in ipsilateral and contralateral acoustic reflex measurements at 500, 1000, 2000, and 4000 Hz (p>0.05). Negative reflex decay was obtained in all participants and no statistically significant difference between the two groups was observed in terms of reflex decay thresholds (p>0.05). Acoustic reflex with high-frequency band noise was observed in five of nine elders whose acoustic reflexes were not obtained at 2000 and 4000 Hz, whereas acoustic reflex with low-frequency band noise was observed in one of six elders who did not show reflexes at 500 and 1000 Hz.Conclusion: It was concluded that although some changes were observed due to age, middle ear and stapes muscles work normally in geriatric group. In the reflex decay test, reliable results were obtained at contralateral 500 Hz. Acoustic reflex measurements with low- and high-frequency band noise may also be used to assess middle ear functions

Role of the middle ear muscle apparatus in mechanisms of speech signal discrimination

A method of impedance reflexometry was used to examine 101 students with hearing impairment in order to clarify the interrelation between speech discrimination and the state of the middle ear muscles. Ability to discriminate speech signals depends to some extent on the functional state of intraaural muscles. Speech discrimination was greatly impaired in the absence of stapedial muscle acoustic reflex, in the presence of low thresholds of stimulation and in very small values of reflex amplitude increase. Discrimination was not impeded in positive AR, high values of relative thresholds and normal increase of reflex amplitude in response to speech signals with augmenting intensity

Predicting the loudness discomfort level from the acoustic reflex threshold and growth function

The purpose of the present study was to evaluate the relationship between several measures of the acoustic reflex [acoustic reflex threshold (ART), dynamic range of the acoustic reflex growth function, the 50% point along the acoustic reflex growth function, and the maximum intensity value of the acoustic reflex growth function] and behavioral measurements of loudness [loudness discomfort level (LDL) and the loudness contour (LC)]. The underlying objective was to determine if any of these measures can be used to predict the LDL. A finding of a strong relationship between these measures could potentially assist in the creation of an objective method to measure LDLs, which may have implications for hearing aid fittings. Prior research in this area has yielded conflicting results. However, very few studies examined measures of loudness growth and the dynamic range of the acoustic reflex. Twenty young adults ranging from 22-35 years of age (Mean age = 25.85, s.d. 3.07) with normal hearing participated in this study. Participants were required to provide a subjective loudness rating to warbled-tone stimuli in accordance with a categorical loudness scaling procedure adapted from Cox et al. (1997), as well as an LDL rating. Additionally, an ART was obtained from each participant, as defined by a 0.02 mmho change in admittance. Following identification of the ART, the acoustic reflex growth function was obtained by increasing the stimulus until the termination point. Experimental measures were obtained over two test sessions. Results revealed no significant relationship between measures of the acoustic reflex and loudness. Analysis of test-retest measures revealed moderate to very high positive (0.70 - 0.92) correlations for the acoustic reflex and LDL measures over a period of 1 day to 2 weeks. Test-retest performance on the majority of loudness categories on the LC did not reveal stable results. Implications for these findings are that the ART cannot be used to reliably predict the LDL. Additionally, the LC may not be a reliable clinical measurement to assess loudness

Contralateral inhibition of click- and chirp-evoked human compound action potentials

Cochlear outer hair cells (OHC) receive direct efferent feedback from the caudal auditory brainstem via the medial olivocochlear (MOC) bundle. This circuit provides the neural substrate for the MOC reflex, which inhibits cochlear amplifier gain and is believed to play a role in listening in noise and protection from acoustic overexposure. The human MOC reflex has been studied extensively using otoacoustic emissions (OAE) paradigms; however, these measurements are insensitive to subsequent “downstream” efferent effects on the neural ensembles that mediate hearing. In this experiment, click- and chirp-evoked auditory nerve compound action potential (CAP) amplitudes were measured electrocochleographically from the human eardrum without and with MOC reflex activation elicited by contralateral broadband noise. We hypothesized that the chirp would be a more optimal stimulus for measuring neural MOC effects because it synchronizes excitation along the entire length of the basilar membrane and thus evokes a more robust CAP than a click at low to moderate stimulus levels. Chirps produced larger CAPs than clicks at all stimulus intensities (50–80 dB ppeSPL). MOC reflex inhibition of CAPs was larger for chirps than clicks at low stimulus levels when quantified both in terms of amplitude reduction and effective attenuation. Effective attenuation was larger for chirp- and click-evoked CAPs than for click-evoked OAEs measured from the same subjects. Our results suggest that the chirp is an optimal stimulus for evoking CAPs at low stimulus intensities and for assessing MOC reflex effects on the auditory nerve. Further, our work supports previous findings that MOC reflex effects at the level of the auditory nerve are underestimated by measures of OAE inhibition

Acoustic Reflex and Extended High-Frequency Testing in Relation to Tinnitus

Tinnitus, a growing concern among adults, is the perception of sound without an external acoustic source. Tinnitus can sound like ringing, buzzing, and clicking and is typically caused by noise-induced hearing loss. Noise-induced hearing loss is caused by prolonged exposure to high levels of noise, which damages the cochlea, and can be temporary or permanent. The purpose of this study is to determine if there are any common factors or characteristics in Acoustic Reflex, standard pure tone and/or Extended High-Frequency testing results between two groups: people who report and do not report tinnitus. This study explores whether Acoustic Reflex testing and Extended High- Frequency audiometric testing results will provide quantitative evidence of ear pathology associated with tinnitus