Assessment of hearing level by means of the acoustic reflex.

It has been suggested that hearing level might be assessed by comparing the acoustic reflex thresholds (ARTs) for two modes of stimulation: by pure tones alone and by a combination of two pure tones, one of which is used as a "preactivator." Using an extrapolatory method for determining the reflex thresholds, 35 subjects (17 normal hearing and 18 hearing impaired) were used to test the above hypothesis. For the individual frequencies 75% of the hearing levels estimated from the ARTs lay within +/- 10 dB of the true threshold, and 97% within +/- 20 dB. However, although the method does appear to be more accurate than the Niemeyer and Sesterhenn method of estimating hearing loss from the ARTs for pure tones and noise bands, it has limitations due to the high levels of preactivating tone required, and the number of stimuli it is necessary to use. Some possible refinements are suggested that might improve the clinical applicability of the technique.