Loudness discomfort level measurements and their implications for the design and fitting of hearing AIDS

A clinical procedure for measuring client loudness discomfort levels which enables a direct comparison with hearing aid SSPL values to be made is presented. Measurements on 45 clients indicate that at any frequency, there is a wide range of LDLs present for any given HTL, and that the shape of the LDL contour across frequency varies greatly from subject to subject. Interviews conducted with fifteen hearing aid wearers indicated that for most of the subjects, those who had been fitted with aids having SSPL well in excess of their LDL values complained of loudness discomfort during aid use, while those with SSPL values less than or approximately equal to their LDL reported no discomfort. It is concluded that hearing aids require SSPL adjustments which allow a large range of average SSPLs and a wide range of SSPL shapes to be achieved. It is suggested that the latter can be readily implemented in hearing aids incorporating compression limiting.