Theoretical Performance Analysis of ANC-Motivated Noise Reduction Algorithms for Open-Fitting Hearing Aids

Existing noise reduction techniques for open-fitting hearing aids typically disregard the occurrence of signal leakage through the openfitting, leading to a degraded noise reduction performance. Recent miniaturization advances enable to incorporate an internal microphone in the ear mould, which is able to record this signal leakage. Recently, feedforward and combined feedforward-feedback active-noise-control-motivated algorithms for noise reduction have been proposed for open-fitting hearing aids. In this paper, a theoretical analysis of these algorithms is presented and the output signal-to-noise ratios (SNR) for a single speech source scenario are derived. It is shown that the performance of the combined feedforward-feedback ANC-motivated (FF-FB ANC) algorithm is independent of the signal leakage. In addition the FF-FB ANC algorithm delivers the highest output SNR of all considered noise reduction algorithms.