Abstract
The objective of this study was to compare the effect and performance of a hearing aid (HA) having a non-linear amplification below 1600 Hz (test HA) with a linear amplifying HA (control HA), aiming towards identical target groups of hearing-disabled people. The investigation was designed as a single-blind crossover interview study, i.e. the interviewer was blind. Thirty-two experienced HA users at a median age of 74 years participated. The observation period was 6–8 weeks for both HAs. For several evaluation parameters the participants found the test HA superior to the control HA, and a significantly better effect of the test HA was indicated in person-to-person conversation in quiet surroundings. Also, quality of sound was significantly better in the test HA, and thus these parameters support the test HA, being preferred by 75%. No significant differences were found in the objectively evaluated parameter, i.e. speech recognition score in background noise (SRSN: S/N = 0) between the two aids. A one-year follow-up examination of those preferring the test HA demonstrated continuously frequent use and satisfaction with the automatic volume control. It is concluded that skilled HA users with a wide range of hearing impairment at an age of 60–80 years prefer a non-linear HA to their current linear HA when fitted monaurally—however, a certain bias in the unblinded test subjects cannot be excluded.