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Relationship between outer ear resonance and permanent noise-induced hearing loss
L L Pierson1, K J Gerhardt, G P Rodriguez
1Department of Communication Processes and Disorders, University of Florida, Gainesville 32611.
Introduction:
Prolonged exposure to noise produces permanent hearing loss in the frequency region centered around 4,000 Hz despite differences in the spectral and temporal characteristics of the noise. It is unclear to what extent properties of the auditory system contribute to the development of permanent hearing loss in this frequency region. This study was designed to evaluate the relationship between the frequency of peak outer ear resonance and the frequency of maximum hearing loss in a population of patients with a history of noise exposure.
Materials And Methods:
Analysis of the frequency of maximum hearing loss was completed with sweep frequency Bekesy audiometry with resolution of 100 Hz. Peak outer ear resonant frequency was determined with a resolution of 175 Hz.
Results:
The mean frequency of maximum hearing loss was 4,481 Hz whereas the mean peak outer ear resonant frequency was 2814 Hz for 43 ears. Pearson product correlation coefficient equaled .64 (P < .0001).
Conclusions:
Despite differences in the type and duration of noise exposure reported by the patients, the positive correlation between outer ear resonant frequency and frequency of maximum hearing loss emphasizes the role that external ear properties play in the development of the 4,000 Hz audiometric notch.