Methods related to the design of intensity modulation fiber-optic microphone are reviewed. A novel scheme to realize the reflective fiber-optic microphone by using single-mode fiber (SMF) fusing multimode fiber (MMF) is proposed and verified experimentally. The MMF with appropriate length and refractive index of parabolic distribution has the function of collimating lens, which is fused with a SMF. For this fiber-optic microphone, the structure is secure, the volume is miniature, and the cost is low. Also there is no intensity noise caused by the instability of higher order mode. By using single frequency sine wave signal source, the fiber-optic microphone is tested. The frequency of output sine wave voltage signal is the same as that of the drive source, and the change of amplitude is linear. The results show that the fiber-optic microphone can be used for voice communication.