Early auditory-evoked responses in the cat: rate effects.

The brain-stem electric responses (BSER) of the cat have been evoked with a 4-kHz tone burst at three stimulus intensity levels, and at interstimulus intervals (ISI) varying fromm 500 to 20 ms. Response amplitude and latency have also been compared in different post-natal age groups, and in bilaterally hearing and unilaterally deaf animals. Increasing reptition rates produce greater latency changes in the youngest animals, whilst all age groups show amplitude decrement at shorter ISI, apart from wave III which increases in amplitude, particularly in bilaterally hearing cats at higher stimulus intensity levels. Wave I shows greater amplitude reduction than do the succeeding waves, which may indicate that the primary cochlear nuclei contribute to later waves of the BSER.