This paper gives an overview to speech enhancement algorithms using a bone-conducted (BC) microphone. Unlike conventional air-conducted (AC) microphones picking up particle movement in the air, the transmission channel of the BC microphone is only related to the human body. Therefore, voice communication with the BC microphone is not affected by ambient noise. However, since the high frequency components of the BC microphone signal are attenuated significantly due to transmission loss, additional signal processing techniques are needed to provide comfortable communication. This paper summarizes the idea of BC-based speech enhancement algorithms. It also provides some pros and cons of the approaches, which might be helpful for determining the direction for further research in the BC microphone-based speech enhancement field.