Potential for Interaction of Low-Level Impulse and Continuous Noise

Abstract

Abstract : The purpose of the experiments described in this report was to establish whether a synergistic interaction occurs between relatively low levels of continuous and impulse noise to produce an increased hearing loss and cochlear pathology. Twenty-three monaural chinchillas were used as experimental subjects. The animals were divided into six groups. Each group was exposed 8 hours per day for 8 weeks to various combinations of impulse and continouous noise presented at various levels. Using behavioral conditioning techniques, hearing thresholds were measured before, during, and after noise exposure. After a minimum of 30 days post-exposure the animals were killed and their cochleas were analyzed using the surface preparation technique. Histological results were qualified in the form of a cochleagram. In contrast to earlier findings the results of this study found no evidence of a synergistic interaction when the animals were exposed to a combination of continuous (between 75-85 dB SPL) and impulse (103 dB SPL peak exposure) noise. (Author)