Far-field cochlear microphonic responses to continuous pure tones recorded from the scalps of cats.

The cochlear microphonic response to continuous pure tones has been recorded in the 'far field' from the scalps of anesthetized cats. Previous methods for scalp recording used tone pip transients only. Our experiments show that the observed wave forms are not due to electrical or mechanoelectrical artifacts. Neural responses such as brain stem responses or the frequency-following response have been excluded as major contributors to the observed wave forms, which are virtually identical to the round window cochlear microphonic response with respect to (1) wave shape with non-sinusoidal stimuli, (2) intensity-amplitude functions, (3) response phase, and (4) amplitude changes due to superimposed band-limited white noise. The methods of ruling out significant artifacts are applicable to non-invasive recordings from humans.