In this paper, we review our recent research on technologies for processing body-conducted speech detected with Non-Audible Murmur (NAM) microphone. NAM microphone enables us to detect various types of body-conducted speech such as extremely soft whisper, normal speech, and so on. Moreover, it is robust against external noise due to its noise-proof structure. To make speech communication more universal by effectively using these properties of NAM microphone, we have so far developed two main technologies: one is body-conducted speech conversion for humanto- human speech communication; and the other is body-conducted speech recognition for man-machine speech communication. This paper gives an overview of these technologies and presents our new attempts to investigate the effectiveness of body-conducted speech recognition.