Speech Enhancement Using Bone Conducted Speech

摘要

Speech enhancement techniques are often required in speech processing applications like hands-free communications, hearing aids and speech recognition. During the past few decades, significant progress has been made in the development of speech enhancement algorithms capable of reducing noise. Unfortunately, such noise reduction methods often introduce distortion and the intelligibility is sometimes degraded in severely noisy environments. In this plenary speech, as an old but new technique for speech enhancement, bone-conducted speech is used. The transmission of voice on bones is called bone conduction. When the voice waveforms are transmitted from the voice source (vocal cord) through the vocal tract wall and skull, they do not confront directly with noise. This is the reason why the bone-conducted speech signal can be utilized in a very noisy environment. However, normally it is known that the quality of bone-conducted speech is comparatively lower than that of normal speech being transmitted through air. This may be caused by the fact that the frequency components more than 1[kHz] deteriorate in bone-conducted speech. A straightforward method to improve the quality of bone-conducted speech is to emphasize the high frequency components. However, this has been not accepted in many cases. One of the reasons of this fact may be that the phenomenon of bone conduction is speaker dependent. Thus, in this plenary speech, as a speaker-dependent technique, the use of an air- and bone-conduction integrated microphone is mainly discussed. Also, it is presented that the quality of bone-conducted speech can be significantly improved by combining adequately both the normal and bone-conducted speech signals. The goal of this kind of research is to obtain a clean speech signal in highly noisy environments.