In order to varify the frequencial specificity of ABR of rat, the authors recorded ABR on the surface of the brain and the potential of the inferior colliculus (I. C) evoked by click and tone pip from 4k to 500Hz.
The results were as follows:
1) Tone pip was more specified than click in the form of power spectral analysis at every frequency.
2) ABR was recorded at every frequency except 1k and 500Hz tone pip. The fast wave of ABR was not evoked by these two stimuli.
3) The tonotopic organization of I. C. was not proved by this experiment. The preceding 2 or 3 waves of the potential in I. C. were not evoked by the stimuli of 1k and 500Hz tone pip. This fact seemed to be the same phenomenon with the diminished fast waves of ABR. The latter nagative potential of I. C. was also reduced by these stimuli which was thought to have less influence upon slow negative 10 (SN10)