Acoustical feedback associated with the use of post aural hearing aids for profoundly deaf children

The feedback properties of 29 ears fitted with post aural hearing aids and hard acrylic earmoulds, have been investigated for a group of profoundly deaf children. Complex loop gain has been measured, and maximum hearing aid gain before instability has been calculated from the measurement results. Guidelines for prediction of maximum hearing loss, which can be managed, are stated, and a suitable hearing aid frequency response for profoundly deaf children is proposed. This response ensures that acoustical feedback above approximately 1 kHz does not limit the low frequency gain, which is assumed to be very important for the speech recognition.