PREFERENCE FOR AND PERFORMANCE WITH DAMPED AND UNDAMPED HEARING-AIDS BY LISTENERS WITH SENSORINEURAL HEARING-LOSS

This study investigated the relationship between acoustic damping of h earing aid responses and listeners' speech discrimination and judgment s of preference and sound quality. Eighteen subjects with essentially equivalent hearing impairments participated. Subjects' speech discrimi nation was evaluated for a male talker in quiet and in noise and for a female talker in the same conditions with hearing aids with 0 dB, -5 dB, and -10 dB of damping. Subjects also compared the damping levels u sing eight bipolar adjective pairs and provided judgments of overall p reference. Measurements of the hearing aid responses were made in a 2- cm(3) coupler and in the subjects' ears using probe microphone techniq ues. Smoothness of the responses was quantified using the Index of Res ponse Irregularity (IRI) and the Frequency Response Smoothness Quantif ication Index (FReSQI). Subjects preferred the two damped hearing aid responses to the undamped. They also had better speech discrimination with damped hearing aid responses. The bipolar adjectives were of limi ted use in comparing hearing aids. A few questions about hearing aid s ound quality and preference appear adequate for evaluating listeners' choice of hearing aids. Smoothness of the hearing aid responses in the test box was higher for the damped hearing aids than for the undamped . However, for real ear responses measured using a probe microphone, s moothness did not change as a function of damping level.