Acoustic reflex thresholds at varying click rates in children

Previous studies conducted with young adults have shown that ipsilateral acoustic reflex thresholds improve with an increase in the click-rate. Older adults also show an improvement in acoustic reflex thresholds with an increase in the click-rate. However, the click-rate induced facilitation (RIF) of acoustic reflex thresholds is significantly reduced in older adults. These results suggest that slower temporal processing in older adults can be documented by measuring the click-RIF of acoustic reflex thresholds. Thus, the click-RIF of acoustic reflex thresholds may prove to be a valuable tool for the assessment of temporal processing disorders in young children. However, click-RIF of ipsilateral acoustic reflex thresholds has not been studied in young normal children. The purpose of this study was to evaluate and document the click-RIF in young normal children to provide normative data for this age-group.

The study included a total of 30 participants (12 male and 18 female) with normal hearing between the ages of 6 and 10 years. Children with outer, middle ear, or neurological disorders were excluded from the study. Ipsilateral acoustic reflex thresholds were determined in the left and right ears with clicks presented at the rate of 50 and 100 per s. The frequency of the probe tone was 226 Hz and intensity was 85 dB SPL. A statistical analysis using a three factor mixed MANOVA was planned to explore differences between ears, click rates and gender.

The MANOVA revealed a significant effect (P=0.0000) for the click-rate. There were no differences between ears or gender and no interactions. The mean click-RIF with an increase in the rate from 50 to 100 per s was 10.50 dB.

Comparison of these results with previous results obtained from young adults suggests that young normal children show click-RIF that is similar to that apparent in young adults.