EFFECTS OF DIFFERING STATES OF ATTENTION ON ACOUSTIC REFLEX ACTIVITY AND TEMPORARY THRESHOLD SHIFT

Temporary threshold shift (TTS) and acoustic reflex activity were observed in 20 normal hearing subjects under several different states of attention. The Zwislocki acoustic bridge (model 3) was used to monitor acoustic reflex activity. Compliance shifts (changes in relative compliance) were measured during exposure of the contralateral ear to a 1000 Hz narrow band noise presented at 105 dB SPL, and TTS was measured at 1000 Hz for the contralateral ear after approximately 412 min of noise exposure. These measures were taken under three different conditions or modes of attention as defined by task performance: reverie (no task performance, high auditory attention), intelligibility test, and high visual attention (visual motor task). Also, levels of attention, as operationally defined by levels of task performance, were considered. From the results of this and other investigations it was concluded that there is a so called central factor involved in acoustic reflex activity although task performance per se, not type of task, is the important factor. However, such a factor in TTS, if observed, is probably an artifact of the type of task performance of the listener. © 1969, Acoustical Society of America. All rights reserved.