Active denoising system for flexibly adjusting denoising signal time delay

Abstract

The invention provides an active denoising system for flexibly adjusting denoised signal time delay. The system comprises a noise collection channel and a music playing channel. The noise collection channel comprises a microphone, an AD converter, a denoising filter, a phase-locked loop which accesses the AD converter and has an adjustable clock frequency, and a first time delay control unit whichis connected between the AD converter and the denoising filter. The music playing channel comprises a music playing source, a first upsampling filter, an adder, a DA converter, a player, and a secondtime delay control unit which is connected between the adder and the DA converter. The adder is used for coupling and superposing a noise reference signal processed by the denoising filter and a music signal processed by the first upsampling filter, thereby outputting a mixed signal. The active denoising system provided by the invention is applicable to different earphone plugs, frequency response of the microphone and the player can be fitted well, and a relatively good denoising effect is realized.

Description

technical field [0001] The invention relates to the technical field of earphone noise reduction, in particular to an active noise reduction system for flexibly adjusting the delay of a noise reduction signal. Background technique [0002] Active noise reduction earphones use the active noise reduction system to emit sound waves in phase opposite to the ambient noise to offset the noise sound waves and eliminate the ambient noise, thereby achieving the effect of noise reduction. The specific principle is to use an external microphone to collect external noise, and then use the active noise reduction system to generate an anti-phase sound wave with the same amplitude as the noise and a phase difference of 180 degrees to cancel the noise, thereby achieving noise reduction. The specific function of the active noise reduction earphone is to reduce the external environmental noise and provide a quiet environment for the wearer. [0003] At present, after a lot of research and dev...

AI Technical Summary

Problems solved by technology

But the digital solution introduces delay problems, including AD conversion delay, DA conversion delay, down-sampling or up-sampling filter delay

If the delay is too large, the anti-phase sound wave cannot be generated, and the active noise reduction will lose its effect; if the delay is too small, the audio sampling rate of the active noise reduction work is required to be high, but this will reduce the accuracy of the noise reduction filter, which cannot be very effective. Good fit to the frequency response of the microphone and speaker, affecting the noise reduction effect

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