A fiber-optic microphone based on intensity modulation has been fabricated and tested. The device possesses sufficient sensitivity to detect acoustic waves in the frequency range from 300 to 3400 Hz. The signal to noise ration is 43 dB relative to 0. 1 pa 1 KHz. Since the device has been fabricated with standard GI (50 / 125) fibers it can be built quite simple and inexpensively with higher stability and reliability. The sensor is compatible with present fiber communication systems including sources, detectors and components.