Objective evaluation of feedback reduction techniques in hearing aids

This paper proposes an objective evaluation of feedback reduction techniques in four commercial hearing aids and one recent feedback cancellation algorithm. The added stable gain was determined for a speech and a music signal in two acoustic conditions. In addition, the reduction of feedback and oscillations at gain values below the maximum stable gain was measured. Added stable gains between 1 dB and 21 dB were found. Most feedback cancellers achieve worse feedback suppression for the music signal than for the speech signal. Constraining the feedback canceller based on an initial feedback path measurement improves the performance for music signals at the expense of a worse feedback suppression in the acoustic conditions that differ from the condition for which the initialization was performed.