Middle latency responses (MLRs) are a series of scalp evoked potentials occurring between 8-50 msec following onset of an acoustic stimulus. The latencies and interpeak amplitudes of the potentials are affected by stimulus intensity, frequency, type of sound, age, temperature and frequency filter setting. The purpose of this study is to demonstrate the effects of intensity, frequency and type of stimuli.

The subjects of this study were 20 normal volunteers between 23 to 33 years of age.

The major results were as follows:

1) The absolute latencies of MLR became significantly shorter with increment of stimulus intensity and frequency (p<0.05).

2) The interpeak amplitudes of MLR became significantly greater with increment of stimulus intensity (p<0.05), while there was no significant change with increment of stimulus frequency.

3) Click-elicited MLR showed shorter absolute latencies and greater interpeak amplitudes than in tone-elicited responses, significantly (p<0.05).

4) The detection rates of MLR became significantly higher with increment of stimulus intensity and with click stimui (p<0.05).

5) There was significant correlation in latencies between V wave of BAEP and Na wave of MLO (p<0.05)