ARE CLINICAL MEASUREMENTS OF UNCOMFORTABLE LOUDNESS LEVELS A VALID INDICATOR OF REAL-WORLD AUDITORY DISCOMFORT

A recent study revealed that most patients were wearing National Healt h Service hearing aids that were capable of exceeding their uncomforta ble loudness level (ULL) measured clinically (Munro et al., 1996). How ever, there is little evidence to show that these clinical measurement s are a valid indicator of real-world auditory discomfort. The aim of this study was to investigate the relationship between ULL and real-wo rld discomfort. The study involved 20 adult subjects, aged 41-92 years , who had been fitted monaurally with an NHS hearing aid. ULLs were me asured using a probe-tube microphone situated close to the eardrum. In dividual real ear to coupler differences were added to the SSPL90 in o rder to predict the maximum power output (MPO) of the hearing aid at t he eardrum. Subjects completed a questionnaire designed to rate the lo udness of different environmental sounds. The results show that the mo re the MPO value exceeded the ULL value, the more likely it was that t he subjects reported loudness tolerance problems to environmental soun ds of long duration. There was a statistically significant correlation between the ULL and discomfort ratings for sounds of longer duration, such as traffic and wind noise; but not for shorter-duration sounds, such as door banging. Subjects did not express real-world auditory dis comfort when the MPO value matched the ULL value. These findings suppo rt the argument for setting hearing-aid MPO close to ULL.