On the Performance of Active Noise Control FX-LMS and FBFX-LMS Algorithms for Duct Network Noise Attenuation

This paper develops an Active Noise Control System (ANC) prototype to be used over a duct network model. The FX-LMS and FBFX-LMS algorithms were implemented using the TMS320C50 fixed point DSP system. Test results show that the FX-LMS algorithm achieves attenuations of up to 43 dB (at 300 Hz) and a mean attenuation of 38.72 dB for frequencies from 100 to 450 Hz. On the other hand, the FBFX-LMS algorithm achieves a mean attenuation of 31.52 dB for the frequency range from 100 to 450 Hz. Moreover, the step size parameter μ was optimized experimentally to obtain the maximum possible attenuation in the frequency range from 100 to 500 Hz. The best possible value for μ was 2048 and the optimized number of filter coefficients was M=128. Finally, the performance analysis illustrates the simplicity of the fixed point DSP solution in the ANC duct network noise cancellation systems.