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ANC earphone audio - Production Test

Project Overview

With the development of TWS (True Wireless Stereo) technology, another equally popular technology is ANC (Active Noise Cancellation), which is a noise reduction technique applied in headphone noise reduction.

The ANC noise reduction technology works by analyzing the sound waves of noise and then sending inverse sound waves to superimpose and neutralize, thereby achieving the effect of noise elimination. The advantage lies in its significant control effect on low-frequency noise, effectively isolating low-frequency noise and reducing the impact of noise on people's health. Generally speaking, the effective frequency range for ANC active noise reduction is between 50Hz and 2kHz. For noises above 2kHz, noise-cancelling headphones can combine passive noise reduction methods through structural design and material selection of the headphones.

An Introduction

The noise reduction effect of ANC headset is determined by two aspects, one is the design of the filter, the second one is a series of gain values of the product. In the RD phase, once the filter design finish (for more RD filter design tools), their will not be changed during the production phase. But during the mass production phase, as the incoming Q mic and loudspeaker quality difference and cavity difference generated during the assembly process, the fixed filter can not garanteed the Noise reduction effect. In order to compensate for these difference, achieve the effect of noise reduction and noise reduction effect of balance, in the mass production phase, a serial of gain value need to be fine-tuned online.

The traditional method is manually adjusted, manually verify, until the noise reduction effect can meet the effect of noise reduction, and then finally, manually burn the gain.

This traditional manual method will cause a series of problems once in the mass production stage:

The adjustment efficiency is low. The average skilled personnel need at least 1~2 minutes, which is a great waste of capacity.
The adjustment precision is low. Because manual adjustment can not be precisely adjusted to the best effect of noise reduction, further more, product consistency is low, and quality can not be controlled, which affects the core competitiveness of products.
The rate of failure is high. For example, AMS chip only have 3 times burning, manual adjustment can not guarantee 100% success, which will lead to an increase the waste of manpower and material resources.
It is no chance to meet the speed requirement of Hybrid product. The hybrid design require FF and FB total 4 registers, it really complicate system. Manually adjustment is unrealistic.

The ANC option of AudioExpert supports the mainstream noise reduction chips, such as AMS, BES, etc. It can automatic adjust a serial of gain, and automatic test and burn the chips on line, further more, base on its sequence editor, user can define other audio test step, such as general frequency response, THD, etc, generate report automatically. MegaSig now has been cooperating with first-rate ANC chip provider, and solution provider, keeping update, creating value for our customers.