Performance comparison between the FxLMS and the FxHLMS algorithms in an Active Noise Control system

The aim of this work is to adapt the Hierarchical LMS algorithm to an Active Noise Control System and to compare its performance with the FxLMS algorithm. Taking into account that the slightest change in the DSP code or in the electro-acoustical arrangement implies lots of experiments in the laboratory that can finish unsuccessfully, we have developed in MATLAB a simulated model of the system in order to test more easily in advance any variation of the basic algorithm. Apart from the cancelling algorithm chosen, the model includes the experimental estimate of the primary and secondary path transfer functions. The model has been tested with the Leaky FxLMS algorithm with shaping of the residual noise previously implemented in the TMS320C32 DSP and the achieved and simulated results have been compared. Not only the effectiveness of the FxHLMS algorithm -in terms of convergence speed, excess mean squared error (MSE) and stabilitybut also the parameters that limit the viability of the implementation on the DSP such as computational costs and address pointers required have been considered.