Development of speech technologies to support hearing through mobile terminal userstaro togawa 1 , takeshi otani 1 , kaori suzuki 2 and tomohiko taniguchi 3Mobile terminals have become the most familiar communication tool we use, and various types of people have come to use mobile terminals in various environments. Accordingly, situations in which we talk over the telephone in noisy environments or with someone who speaks fast have increased. However, it is sometimes difficult to hear a person s voice in these cases. To make the voice received through mobile terminals easy to hear, authors have developed two technologies. One is a voice enhancement technology that emphasizes a caller s voice according to the noise surrounding the recipient, and the other is a speech rate conversion technology that slows speech while maintaining voice quality. In this paper, we explain the trends and the features of these technologies and discuss ways to implement their algorithms on mobile terminals. Cellular phones and smartphones are communication tools that can be easily used anytime and anywhere, including in noisy environments. When a user is talking over the telephone in a noisy environment, his/her voice sent to call partner on the other end of the line (sending voice) mixes with the surrounding noise and becomes difficult for the call partner to hear, and the voice that is sent by the call partner (received voice) is buried by the noise surrounding the user. However, various speech technologies for improving the quality of the received voice have been developed and installed in mobile terminals. For example, a noise suppression technology that suppresses only the noise from the sending voice, with which the noise mixes, to improve voice quality has been developed [1]. In addition, a voice enhancement technology that emphasizes the call partner's voice according to the volume and type of surrounding noise in noisy environments such as station platforms has been developed and installed. Furthermore, a speech rate conversion technology that slows the fast voice of the call partner while maintaining voice quality has been developed and installed.We first explain the trends and technical features of voice enhancement technologies for improving the quality of the received voice according to the usage environment of the mobile terminal in Section II and those of speech rate conversion technologies in Section III. We then explain the implementation of the algorithms of our proposed technologies in mobile terminals in Section IV and explain other technologies for improving the quality of the received voice in Section V. Finally, we explain future applications of the speech technologies in Section VI. I IIt is generally known that the quality of received voice is deteriorated by the noise or the reverberation generated in the user environment or the call partner's environment, and information compression according to audio coderdecoder (CODEC) when talking over the telephone with the mobile terminals. However, various speech techno...

No abstract