Mobile 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.
