Low-level acoustic reflex thresholds

Abstract

The acoustic reflex threshold can be detected at lower than normal sound pressure levels by means of facilitation. This procedure entails simultaneous presentation of a high-frequency facilitating tone at a level just below reflex threshold and a second reflex-eliciting tone. The second tone is reduced in intensity until no further reflex activity is observed. When hearing was normal, less signal intensity was needed to elicit the acoustic reflex when facilitation was used. There was a greater amount of reflex threshold improvement when the facilitating and eliciting tones were presented monotically. Sensorineural hearing loss allowed small or no reflex threshold change with facilitation.