Audio adjustment method and associated audio adjustment circuit for active noise cancellation

An active noise cancellation (ANC) adjustment method, applicable to an ANC circuit, the ANC circuit comprising an audio receiver and an audio input unit, the audio receiver being configured to receive sounds, the ANC adjustment method comprising:

• generating a first time domain signal according to an audio to be broadcast or a sound testing signal by the audio input unit;
• generating a second time domain signal according to a background sound received by the audio receiver, wherein the background sound corresponds to the audio to be broadcast or the sound testing signal;
• performing time-frequency conversion upon the first time domain signal and second time domain signal to obtain a first frequency domain signal and a second frequency domain signal respectively;
• generating a frequency response according to the first frequency domain signal and the second frequency domain signal;
• and
• adjusting an active noise cancelling coefficient of the ANC circuit according to the frequency response to improve a noise cancellation effect;
• wherein the frequency response is transmitted to a filtering design unit, the filtering design unit generates a filtering coefficient to improve the active noise cancelling coefficient according to the frequency response, and
• the step of adjusting the active noise cancelling coefficient of the ANC circuit according to the frequency response to improve the noise cancellation effect comprises:
• generating an adjusted active noise cancelling coefficient according to the filtering coefficient, and feeding the adjusted active noise cancelling coefficient back to the audio to be broadcast or the sound testing signal for calculating a difference between a phase of the first time domain signal and a phase of the second time domain signal.