Gain and feedback problems when fitting behind-the-ear hearing aids to profoundly hearing-impaired children.

Previous laboratory studies with severely and profoundly hearing-impaired persons aided with behind-the-ear (BTE) hearing aids have resulted in prediction rules for insertion gain and maximum gain without occurrence of acoustic feedback. The practicability of these findings was investigated in the present field trial with 21 profoundly deaf children fitted with power BTE hearing aids. In dialogue situations without background noise, the gain control settings were in accordance with the insertion gain prediction rule, whereas preferred gain may be 10 dB lower in the presence of noise. Consistent with the prediction rule for maximum gain without feedback and the gain response of the present test hearing aid, we observed oscillation in the high-frequency range in which the children had no remaining hearing. When the high-frequency gain was reduced, sufficient low-frequency gain could be provided without feedback problems.