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Recent studies involving guinea pigs have shown that noise can damage the synapses between the inner hair cells and spiral ganglion neurons, even with normal hearing thresholds-which makes it important to investigate this kind of impairment in humans. The aim was to investigate, with multiple audiological assessments, the auditory function of normal hearing workers exposed to occupational noise. Altogether, 60 workers were assessed (30 in the noise-exposure group [NEG], who were exposed to occupational noise, and 30 in the control group [CG], who were not exposed to occupational noise); the workers were matched according to age. The following procedures were used: complete audiological assessment; speech recognition threshold in noise (SRTN); speech in noise (SN) in an acoustic field; gaps-in-noise (GIN); transient evoked otoacoustic emissions (TEOAE) and inhibitory effect of the efferent auditory pathway; auditory brainstem response (ABR); and long-latency auditory evoked potentials (LLAEP). No significant difference was found between the groups in SRTN. In SN, the NEG performed worse than the CG in signal-to-noise ratio (SNR) 0 (p-value 0.023). In GIN, the NEG had a significantly lower percentage of correct answers (p-value 0.042). In TEOAE, the NEG had smaller amplitude values bilaterally (RE p-value 0.048; LE p-value 0.045) and a smaller inhibitory effect of the efferent pathway (p-value 0.009). In ABR, the NEG had greater latencies of wave V (p-value 0.017) and interpeak intervals III-V and I-V in the LE (respective p-values: 0.005 and 0.04). In LLAEP, the NEG had a smaller P3 amplitude bilaterally (RE p-value 0.001; LE p-value 0.002). The NEG performed worse than the CG in most of the assessments, suggesting that the auditory function in individuals exposed to occupational noise is impaired, even with normal audiometric thresholds.

RESUMEN

INTRODUCTION: Few population-based studies have quantified hearing levels in Brazil; additional studies on this subject are needed. PURPOSE: The purpose of this study was to characterize hearing complaints and the audiological profile of the population served by the Clinical Audiology Service of an Academic Health Center in the western region of São Paulo, Brazil, between 2003 and 2008. An additional aim was to check whether there is a positive association between the signs/symptoms and type of hearing loss. METHODS: This was a retrospective study of the records of 2,145 patients. The health history, tonal and vocal audiometry, and imitanciometry findings were analyzed. RESULTS: The mean age of the patients was 20.6 years. The majority of the subjects had normal hearing thresholds, and the prevalence of hearing loss was approximately 35%. As the patient's age increased, the frequency of conductive hearing loss decreased and that of sensorineural hearing loss increased. There was a tendency toward hearing loss worsening with age. CONCLUSION: Hearing complaints can predict the type of hearing loss; therefore, they should always be valued because they can be used as a form of screening and thus help to determine the diagnostic hypothesis. This could help to reduce the gap between the patient's perception of the complaints and the audiological assessment and thus improve the prognosis.

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RESUMEN

INTRODUCTION: Few population-based studies have quantified hearing levels in Brazil; additional studies on this subject are needed. PURPOSE: The purpose of this study was to characterize hearing complaints and the audiological profile of the population served by the Clinical Audiology Service of an Academic Health Center in the western region of São Paulo, Brazil, between 2003 and 2008. An additional aim was to check whether there is a positive association between the signs/symptoms and type of hearing loss. METHODS: This was a retrospective study of the records of 2,145 patients. The health history, tonal and vocal audiometry, and imitanciometry findings were analyzed. RESULTS: The mean age of the patients was 20.6 years. The majority of the subjects had normal hearing thresholds, and the prevalence of hearing loss was approximately 35%. As the patient's age increased, the frequency of conductive hearing loss decreased and that of sensorineural hearing loss increased. There was a tendency toward hearing loss worsening with age. CONCLUSION: Hearing complaints can predict the type of hearing loss; therefore, they should always be valued because they can be used as a form of screening and thus help to determine the diagnostic hypothesis. This could help to reduce the gap between the patient's perception of the complaints and the audiological assessment and thus improve the prognosis.

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