EFFECT OF SINGLE IMPULSES ON COCHLEAR MICROPHONICS OF COCHLEA FROM GUINEA-PIG

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  • 1 January 1977
    • journal article
    • research article
    • Vol. 36  (7-8) , 1097-1105
Abstract
The influence of highly intensive single impulses on the cochlea of guinea pig was studied in an acute experiment. Very short impulses of .ltoreq. 0.1 ms duration were produced by a spark-noise generator. The cochlear microphonics (CM) to a test stimulus (3150 Hz) were recorded from the round window and measured prior to, during and following impulse treatment. During the impulse treatment, the greatest amplitude reduction of CM occurred after the 1st impulse, while the further impulses caused a decreasing reduction. At first the number of impulses was varied: 1, 3, and 5 impulses were applied at intervals of 15 s each, at an impulse sound level of 164-dB sound pressure level referred 0.002 .mu.bar (SPL). After these impulse treatments, in all cases a continual decrease of CM amplitudes up to a constant end value without recovery was found within a 2 h period of observation. The height of the end value depended on the number of impulses applied. Subsequently, at an exposure to 5 impulses the impulse sound level was stepwise reduced (164, 153, 144, 139 and 133 dB SPL). Again, a characteristic decrease of CM amplitudes was observed during the 2 h observation period. The height of the end value was now dependent on the impulse sound level. Impulses of 164, 153 and 144 dB SPL caused a strong decrease of CM while the effect of impulses of 139 and 133 dB SPL was distinctly lower.

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