Frequency Shifting for Acoustic Feedback Control in Hearing Aids

Improved proportionate affine projection algorithm (IPAPA) has been known as an effective algorithm for acoustic feedback control since it leverages the sparseness of the feedback channels as well as the fast convergence algorithm for adaptive filter. To further improve the performance of the IPAPA we propose to integrate the frequency shifting technique into the forward path. By adding a small amount of frequency shifting, the correlation between the loudspeaker signal and the incoming signal can be significantly reduced, resulting in a smaller bias in estimating the feedback channel. Simulation results show that the proposed method achieves faster convergence and tracking rates than the one without using frequency shifting. The normalized misalignment (MIS) and added stable gain (ASG) are also significantly enhanced. We also propose to use l0-norm, a good alternative to the l1-norm, for the IPAPA to achieve further improvement on the performance.