Portions of tone pips contributing to frequency-selective auditory brain stem responses.

The portions of tone pips that are effective in increasing the amplitudes of auditory brain stem responses were studied using 6 cats. The responses evoked by pips with identical slopes but different rise times were compared to one another. The results indicated that the effective portion of the tone pips extended more than 4 ms from onset at 500 and 1 000 Hz, and more than 2 ms at 2 000 Hz. Each cycle within these ranges contributed to the increase in response amplitude. These results support the contention that the frequency selectivity of the brain stem response elicited by tone pips is sufficient for objective audiometry.