Influence of response-time limits on automated hearing threshold determination.

Objective: In automated hearing threshold determination procedures, prespecified response- time limits can be applied to evaluate whether a stimulus was truly heard by checking whether the test subject reacts to the onset and the offset of the stimuli within given time intervals. The influence of different response-time limits on the threshold of normal-hearing test subjects was investigated.
Design: Two-stage hearing threshold level measurements applying the ISO 8253-1 (2010) bracketing procedure were performed. Pre-tests at 125 Hz and 1000 Hz were carried out with maximum accepted response times of 600 ms, 1000 ms, and 1200 ms. Subsequently, thresholds were measured at the seven octaves between 125 Hz and 8000 Hz with maximum accepted response times of 600 ms and 1000 ms.
Study Sample: 15 test subjects in pre-tests, 25 test subjects in the main study.
Results: Threshold levels determined with a maximum accepted response time of 1000 ms are 2.6 dB lower than those obtained with a maximum accepted response time of 600 ms (95% CI -1.6 dB to 6.9 dB). The threshold shift was similar at all frequencies.
Conclusions: Based on this study, response-time limits after both stimulus onset and offset of at least 1000 ms are recommended.