Abstract
The cochlear microphonics (CM) response to two-tone stimuli was measured before and after exposure to 4kHz pure tone at 100dB SPL or 125dB SPL. The 2f1-f2 distortion products in the CM (CM-DPs) were markedly suppressed by the sound exposure at either intensity, although the loss of CM output at the primary frequencies was limited to 4dB or less. The suppression of CM-DPs was greater as the intensity of primary tones decreased, especially at primary intensities below 55dB. These results show that the active transduction process in the cochlea was affected by acoustic overstimulation. This impairment of active transduction was postulated to be an initial process in developing noise induced temporary and/or permanent threshold shift.
