Preferred compression threshold with 2: 1 wide dynamic range compression in everyday environments

A large-scale field trial was carded out to investigate client preferences for input controlled compression (AGC(i)) in single channel wide dynamic range compression hearing aids. The aims were: to find which compression threshold or mode of amplification was preferred by the majority of subjects, and what distinguished the subjects who chose each setting or mode; to determine what proportion of people do not choose to use the volume control; to find out what proportion of people prefer to use the remote control for adjusting the volume of the hearing aid; and to identify what characterises people who do or do not choose to vary the volume control. Subjects were 140 adult clients of Australian Hearing Services fitted with multi-memory hearing aids. In Trial One, the subjects compared AGC(i) thresholds of 50 dB SPL and 66 dB SPL. Sixty percent of clients preferred the higher AGC(i) threshold (66 dB SPL), 31% preferred the lower threshold (50 dB SPL), with 9% undecided. In Trial Two, the subjects compared their preferred AGC(i) threshold combined with AGC(o) compression limiting to AGC(o) compression limiting alone. Fifty-five percent preferred AGC(i) (plus AGC(o)), 31% preferred AGC(o) alone, with 14% undecided. In this trial, 49% used the volume control more than once a day; and the majority of subjects (86%) preferred to use the remote control to adjust the volume. No characteristics were found to distinguish between those who preferred the different compression thresholds, or between those who did or did not need to vary the volume of the hearing aid. It is concluded that, in the absence of any information to the contrary, for single channel fast acting compression hearing aids with a 2:1 compression ratio, compression thresholds of 60 to 66 dB seem an appropriate initial level.