Abstract: A voice changer for use generally with a telephone includes a first port for receiving signals from a microphone or the hand set, a second port for connection to a microphone or a telphone set, and a voice changer circuit for selectively changing the frequency content of voice signals transmitted between the first and second ports. The clocking frequency of analog to digital and digital to analog converters connected to a continuously operating real-tim CPU varies the frequency content of the voice signal to provide masking of voices, for example changing a male to a female voice or a female to a male voice.