Insertion gain measurements using two low-powered analogue hearing aids

Differences between insertion gain measurements and coupler measurements we re investigated using two different hearing aids, to assess the accuracy of hearing aid fitting methods which involve the use of real-ear-to-coupler d ifferences (RECDs). The hearing aids used were the NHS BE19 and the Lavis X 11. They were allocated alternately to 80 new adult hearing aid users, and insertion gain measurement was carried out with the allocated aid on all su bjects. and with both hearing aids on 36 subjects. Coupler measurements wer e also carried out with both hearing aids, at two different gain settings. Comparison of the coupler measurements and the insertion gain measurements suggests that the differences in insertion gain produced by different heari ng aids cannot be predicted accurately from the differences in coupler gain measurements produced by the same aids. Although the use of RECDs measured using insert earphones may accurately predict the real-ear performance of some models of hearing aid, this method may not produce equally satisfactor y results with other models.