Acoustic reflex temporal summation measured at threshold.

This study measured the threshold of the acoustic reflex as a function of reflex-activating stimulus duration. Acoustic reflex thresholds (ARTs) were measured for tonal stimuli at frequencies of 1000 and 3000 Hz and broadband noise at six durations between 20 and 500 msec for both normal and hearing-impaired subjects. Traditional techniques and response averaging were used. Results suggest that these methods have a significant influence on ART and reflex temporal summation at threshold. Lowest thresholds and almost no temporal summation were found with a response averaging technique and a bidirectional shift criterion, whereas clinical procedures yielded highest thresholds and greater summation. These results suggest a need to examine the methodology used for measurement of the acoustic reflex and the interpretation of clinical pathology based on measurements of reflex temporal summation.