The effect of probe frequency on ipsilateral acoustic reflex thresholds

This study was designed to evaluate the effects of gender and probe frequency on the ipsilateral click-evoked acoustic reflex thresholds. Ipsilateral acoustic reflex thresholds were obtained from the left ear of each subject (12 male and 12 female normal young adults) by presenting clicks at the rate of 180/sec. The probe tone frequencies were 226, 678 and 1.000 Hz. The results revealed that acoustic reflex thresholds for the 678 Hz probe were significantly higher than those obtained with the 226 and 1.000 Hz probes. No gender differences were apparent. However, the static admittance was significantly correlated with the acoustic reflex thresholds for the 678 Hz probe in only the female subjects. For the 226 Hz probe, the elicitation of the reflex resulted in a decrease in static admittance in all the subjects. For the 678 Hz probe, the admittance decreased in 58% of the subjects and it increased in 42% of the subjects. For the 1,000 Hz probe, an increase in admittance was apparent in all of the subjects. The results suggest that either the 226 Hz or the 1,000 Hz probes can be used for the measurement of click-evoked acoustic reflex thresholds in adults.