Relative benefits of stepped and constant bore earmoulds: a crossover trial.

Twenty-one first-time hearing aid candidates took part in a crossover trial which compared a stepped earmould of the 8CR design with a standard constant-bore earmould, each fitted to a low-powered National Health Service behind-the-ear hearing aid. Before fitting the aid, and also after 2-week trials with each earmould, aided speech-in-noise discrimination scores were obtained, along with subjective ratings according to a series of descriptive scales, and overall preference for one or other of the aids. Aided speech-in-noise scores were, on average, 2.4% higher for the stepped earmould. Two-thirds of the subjects preferred the stepped earmould and it was also rated as more clear on a clear-hazy descriptive scale. After the 4 week trial period, there was a tendency for the stepped earmould to be preferred by subjects with more sensitive hearing thresholds at 2 kHz and higher aided speech-in-noise scores with either earmould, although this was not true at the initial fitting.