Auditory evoked responses in awake rabbits after exposure to high intensity noise impulses.

Impulse noise effects were tested in chronic experiments on 8 awake rabbits. Alterations of cochlear potentials and evoked responses from the inferior collinulus and the medial geniculate body were studied. The rabbits were subsequently exposed to 10 noise impulses of 144 dB SPL, then (after recovery) to 10 impulses of 153 and 164 dB SPL. After exposure the amplitudes of all potentials were reduced. Time of restitution depended on the intensity of the noise, the restitution failed after exposure to 164 dB SPL impulses. Time lapses of the amplitude-reduction and restitution process were comparable for both structures of the auditory pathway. The peak latencies were prolonged significantly in only two of the rabbits after this impulse intensity. Impulses of 164 dB SPL were followed by irreversible changes of all evoked responses.