The use of the Middle Latency Response (MLR) for assessing low‐frequency auditory thresholds

Abstract

Several investigations have suggested using the MLR to test low‐frequency hearing thresholds (i.e., 500 Hz). Recently, a new stimulus paradigm has been proposed [R, Galambos et al., Proc. Natl. Acad. Sci. 78, 2643–2647 (1981)] that increases the detectability of the MLR at low sensation levels. In the past, the MLR has been regarded as being relatively unaffected by sedation or sleep. We are investigating this evoked potential with normal hearing adults, and find that, contrary to previous reports, it can be affected by sleep. That change can show considerable inter‐subject variability. Specifically, there is a significant reduction in the response amplitude for a number of the subjects, which could possibly affect the accuracy of this evoked potential in determining auditory thresholds. We have also begun to monitor the EEG in an attempt to correlate MLR changes with specific stages of sleep. Our findings will be summarized in the presentation.