Acoustic Feedback Cancellation in Hearing Aids Using Least Squares Delay Based Algorithm in Fuzzy Interactive Controller

The acoustic feedback is a persistent and annoying issue in hearing aids, which either limits the maximum gain accessible by the user or degrades the sound quality of the device or both. Feedback cancellers are utilized to produce a replica of the feedback signal (FS), in order to remove the original FS before being delivered to the loudspeaker component; however, a bias due to correlation of input-output signals, was introduced into the system, due to spectrally colored nature of input signal. The Least Squares Delay (LSD) based adaptive algorithm was utilized, in which the filter coefficients were updated individually to minimize the bias, however under slow convergence rate. A novel approach of introducing a Fuzzy interactive controller (FIC), evaluates the performance measures of LSD algorithm, by incorporating a Rule-Decision-Table to generate the linguistic rules. The FIC-LSD algorithm adapted the system output in proportion to the magnitude of estimated filter coefficients. The steady-state performance achieved through FIC, were compared with various well-known adaptive techniques and the obtained results proved that the FIC integrated LSD algorithm would provide a significant and robust acoustic feedback cancellation in the presence of varying environmental conditions.