Acoustic Feedback Cancellation Based on Adaptive Projection Subgradient Method in Hearing Aids

Adaptive projection subgradient method(APSM) is used in this paper for feedback cancellation in hearing aids. APSM is derived from the technique of projection onto convex sets (POCS) and parallel subgradient projection algorithm (PSP). It utilizes the subgradient projection hyperplanes as the searching area of the relax factor in the process of relaxed projection. We applied this APSM algorithm for acoustic feedback cancellation in hearing aids. Numerical experiments demonstrate that notable improvements are achieved including speed, stability and accuracy of convergence compared to the traditional NLMS algorithm. Another exciting conclusion by further experiments is that APSM achieves excellent performance in the situation that real speech segment as input in hearing aids, and APSM is more robust for low SNR compared to other algorithms.