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Sound quality improvement for the body-conducted speech of a sentence unit using differential acceleration

Speech is a human instrument for communication, and many applications of speech have been proposed. However, the sound quality of speech is reduced by noise in air, and many researchers and engineers have investigated speech measurement methods in noisy environments in terms of signal processing and the use of noise-robust microphones. Conventional approaches of signal measurement can measure speech in an environment with a high signal-to-noise ratio; however, these approaches do not work well in an environment with a low signal-to-noise ratio. By contrast, body-conducted speech, which is speech conducted through the bone and skin of the human body, can be measured in such an environment. However, the frequency characteristics of body-conducted speech are poorer than those of air-conducted speech, and the sound quality needs to be improved for speech applications and conversations. With this background, the paper discusses and investigates sound-quality improvements for the sentence unit of body-conducted speech using differential acceleration, which is a signal retrieval method employed to improve sound quality. The performance of the method is investigated in terms of signal retrieval from body-conducted speech recorded by an accelerometer and Optical Fiber Bragg Grating microphone.