Speech enhancement for an in-ear communication system using bone-conducted and acoustic signals
Kyriakos Papanagiotou, Boaz Rafaely, Christine H. Shadle · The Journal of the Acoustical Society of America · 2001
The main requirement for mobile radiotelephony nowadays is an ergonomic, robust, and functional system. One weak point of existing devices, such as hands-free kits for mobile telephones, is poor speech intelligibility due to factors such as environmental noise and poor signal reception. This work investigates the potential of speech enhancement using post-processing of signals from two types of transducers: a miniature microphone placed on the opening of the ear canal, and a miniature accelerometer mounted on four locations around the head. The microphone provides good speech quality with the drawback of being sensitive to external noise, while the accelerometer senses vibrations that are immune to ambient noise, but are a distorted, low-pass-filtered version of speech sounds. The use of optimal filtering, which enhances the signals acquired from the miniature transducers by matching them to a reference recording of the same material, was investigated. The methods investigated here could then be applied to improve speech quality and reduce noise in communication earsets. Initial results with speech, based on sustained phonemes and phonetically balanced sentences, showed potential for improvement in the quality of the speech signals and also suggested that different filters might be used for different phonemic contexts. [Research funded by EPSRC Grant No. GR/M86026.]