Reliability and effect of stimulus parameters on the acoustic reflex latency test in adults with normal hearing

Abstract

Abstract Purpose The current study aimed to investigate the effect of different procedural variables on the acoustic reflex latency (ARL) in a population of adults with normal hearing. In addition to normative values, the study also evaluated the test-retest reliability of tonal and broadband ARL measures.

Method The study followed a descriptive, within-subject research design. Participants included 31 normal hearing individuals (aged 18 – 30 years old, mean age 23.08 SD 2.42). Participants were required to present with normal behavioural pure tone thresholds, distortion product otoacoustic emissions, and acoustic reflex threshold (ART). ARL testing was completed using 500 Hz, 1000 Hz, 2000 Hz and 4000 Hz, broadband noise (BBN), high (HBN) and low-band noise (LBN) stimuli, presented ipsi- and contralaterally. Participants underwent ARL measurement sessions with the repeat assessment within one week.

Results Ipsilateral P1 latencies were significantly shorter (mean 53.00 ms SD 2.91) at 15 dB above ART than contralateral P1 (initial onset) latencies (mean 64.00 ms SD 3.92). No significant P1 differences were found between ears or gender either ipsi- or contralaterally. A linear regression analysis found intensity at 10 dB above ART to significantly influence P1 ipsi- and contralateral latencies. No significant test-retest difference was found at 10 dB above ART for P1 ARL (p<0.05). Significant P1 differences were, however, evident at 5 and 15 dB above ART (p>05).

Conclusion ARL measurement at 10 dB above ART elicited reliable ARL measurements, facilitating more accurate ARL measurements than 5 or 15 dB above ART. The study highlights the clinical utility of ARL measurements within the context of modern, digital equipment.