A Research on Acoustic Hear-Through Technology Based on an Active Noise Cancellation Headphone System

Since in-ear headphones have high-level isolation, ambient sounds that transmit to the human eardrum are attenuated as they pass through the headphones. Acoustic Hear-Through (HT) or acoustic transparent transmission technique is used to enable natural listening of ambient sounds while wearing headphones. Based on the structure of in-ear headphones with active noise cancellation, this paper presents the design of an acoustic HT digital filter and embeds the headphone system with HT function. Combined with the speech spectral subtraction algorithm, the speech enhancement is applied based on the HT system to achieve selective HT of noisy speech. Compared with the acoustic transfer functions in the natural listening environment and the no HT headphone-wearing environment, the proposed HT headphone performs well in reducing the attenuation of the headphone system. Finally, the idea that the proposed selective HT function has great potential to improve the quality and intelligibility of the noisy speech heard by the eardrum is verified.