Some effects of the stimulus repetition rate on N1 and N2 in transtympanic and surface recordings

Acoustic reflex monitoring during the presentation of 1000 clicks at high repetition rates

This study was designed to monitor acoustic reflexes during the type of stimulation used in the auditory brainstem measures. Twenty normal female subjects within the age range 20 to 26 years participated in the study. The probe tone frequency was 226 Hz and the intensity was 85 dB SPL. Approximately 1000 clicks were presented to the right ear through an insert earphone and acoustic reflexes were monitored in the left ear. The clicks were presented at 95 and 105 dB peSPL and at 50 and 100/sec rates. At the rate of 50/sec, the acoustic reflex was present in 70% of the subjects at 95 dB peSPL and in 85% of the subjects at 105 dB peSPL. At the rate of 100/sec, the reflex was present in 80% of the subjects at 95 dB peSPL and in 95% of the subjects at 105 dB peSPL. The ANOVA on the acoustic reflex amplitudes showed an increase in the amplitudes with an increase in the click rates and levels.