The effect of hearing-aid compression on judgments of relative distance

Abstract

The overall level of a sound is an important auditory cue to distance in rooms, but this cue might be affected adversely by the amplitude compression found in most modern hearing aids because this explicitly changes levels. This prediction was tested using a synthetic-distance design to measure the just-noticeable difference (JND) in distance from distances of 2 or 5 m. Twenty-six aided listeners participated. The results did not show any effect of compression ratio upon JNDs. A possible interpretation is that the listeners had acclimatized to the effect their aids have on level.

FIG. 1

The just-noticeable differences (JNDs), in meters, plotted as a function of the better-ear hearing loss for listeners fitted with two linear aids (open circles), one linear and one compressive aid (diamonds), and two compressive aids (hourglasses). The dots plot the JNDs measured using 77 unaided listeners from Akeroyd et al. (2007), and the lines show exponential curves fitted to these data. The largest hearing loss for the unaided listeners was 59 dB, and so the lines have been extrapolated above that value to the higher hearing losses of the aided listeners. The four panels are for the four tasks (see text).

FIG. 2

The JNDs plotted as a function of the average compression ratio. The four panels are for the four tasks.