EC-ANC: Edge Case-Enhanced Active Noise Cancellation for True Wireless Stereo Earbuds

In this paper, we propose an edge case-enhanced active noise cancellation (EC-ANC) system that integrates a piezo microphone, a signal processor, and a wireless module into the charging case of TWS earbuds. Considering the fact that sound travels much faster in solid materials than in the air, the piezo microphone on the edge case will pick up a lookahead signal before it reaches the earbuds. The lookahead signal is very useful for real-time noise cancellation, especially for eliminating high-frequency, unpredictable, and high dynamic range noises. Benefiting from the speed advantage of sound traveling in solid materials, EC-ANC performs well when the charging case is either close to the user or near the noise source. This allows EC-ANC to be easily applied to various noise cancellation scenarios. We implemented EC-ANC on Intel MAX 10 FPGA, and then validated its advantages over the popular ANC method adopted by Bose, Sony, and Apple. According to experiment results, EC-ANC can achieve higher noise attenuation in the 4 kHz range compared with Bose QuietComfort 20 (QC20) and Bose QuietComfort Earbuds (QCE). Even without the noise-absorbing material, EC-ANC's performance at higher frequencies is comparable to QC20 and QCE.