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Fusing Bone-Conduction and Air-Conduction Sensors for Complex-Domain Speech Enhancement

Speech enhancement aims to improve the listening quality and intelligibility of noisy speech in adverse environments. It proves to be challenging to perform speech enhancement in very low signal-to-noise ratio (SNR) conditions. Conventional speech enhancement utilizes air-conduction (AC) microphones, which are sensitive to background noise but capable of capturing full-band signals. On the other hand, bone-conduction (BC) sensors are unaffected by acoustic noise, but recorded speech has limited bandwidth. This study proposes an attention-based fusion method to combine the strengths of AC and BC signals and perform complex spectral mapping for speech enhancement. Experiments on the EMSB dataset demonstrate that the proposed approach effectively leverages the advantages of AC and BC sensors, and outperforms a recent time-domain baseline in all conditions. We also show that the sensor fusion method is superior to single-sensor counterparts, especially in low SNR conditions. As the amount of BC data is very limited, we additionally propose a semi-supervised technique to utilize both parallelly and unparallely recorded AC and BC speech signals. With additional AC speech from the AISHELL-1 dataset, we achieve similar performance to supervised learning with only 50% parallel data.