Interaction of age and intersignal interval on acoustic reflex amplitude.

We studied the effect of intersignal interval (ISI) on the averaged acoustic reflex in nine young and nine elderly subjects. Over the range of ISIs from 1.5 to 9 sec, there was an interaction between ISI and age group, but the effect was unique to reflex mode. Results emphasize the importance of measuring both crossed and uncrossed reflex waveforms, in the study of aging, and of controlling the ISI in order to avoid overestimation of aging effects.