Abstract: An audio vehicle speedometer in which two pulse trains, one having a frequency which varies as a function of vehicle speed and the other having a frequency which varies as a function of desired vehicle speed indicated by the manually set portion of a potentiometer, are produced and compared to produce a further pulse train having a frequency which varies as a function of the difference frequency between the first two trains. The further train is applied to a speaker to produce an audio pulse train whenever the vehicle speed exceeds the desired manually set speed.