Investigation of Aided Thresholds and Functional Gain Measured by a New Procedure of Sound Field Audiometry

Abstract

In 48 patients who had a moderate hearing impairment and were fitted hearing aid in our department, aided thresholds and word discrimination test at the final hearing aid setting were measured by a new procedure of sound-field measurement with a head-worn small speaker (Virtual Phone, SONY). The average aided thresholds were about 30dBnHL at 250-2000Hz. Those were same as our initial targets of hearing aid fitting. The average functional gain was most similar to POGO method in three prescriptive methods; the gain for 30dBnHL of desired aided level, NAL-R and POGO. The patients with good discrimination showed flat contour of 30dBnHL at 250-2000Hz in aided thresholds, whereas, the patients with poor discrimination had higher thresholds at 250 and 500Hz. We considered that the flat aided thresholds of 30dBnHL is valid target for hearing aid fitting.