In factories, workers suffer from noise induced hearing loss.
They sit along the production line and are exposed to the noise
generated by manufacturing equipment for prolonged hours. Protective
measures are urgently needed to solve this problem. Since
verbal communication may be hindered by passive noise control,
ANC seems to be the most feasible solution [1]. In an ANC system,
the noise source is called the primary source. The secondary
source, a.k.a. the control source, transmits an anti-noise wave with
the equaling amplitude and opposite phase of the noise wave.
Based on the superposition principle of sound waves, cancellation
of the noise wave can be achieved at the control point, where the
error microphone is set up to make the ANC system a closed loop
control