Abstract: A microphone which consists of a speaker having a base resonant frequency, a suppression circuit for reducing the frequency response of the speaker at the base resonant frequency, and a high pass filter for reducing the base frequency response of the speaker is disclosed. The speaker creates electrical signals in response to sound waves received and the suppression apparatus reduces the relative magnitude of the electrical signals having frequencies substantially equal to the base resonant frequency of the speaker. The high pass filter reduces the magnitude of all electrical signals having frequencies below a predetermined frequency, and thus a desired microphone frequency response is obtained.A communications system which uses a receiver to drive a speaker in one mode of operation and uses the speaker as a microphone followed by a compensation network and a transmitter in another mode of operation is also disclosed.