Abstract: A system for measuring distance to an object. The system comprises a device for producing a high frequency sound impulse. There is a receiver for a high frequency echo sound impulse reflected from the object. A depth clock is connected to clock a counter. An initiator for the depth clock initiates the clock at a first time corresponding to the time of production of the high frequency sound impulse. The depth clock is stopped at a second time corresponding to the time of receipt of the echo sound impulse. The content of the counter is proportional to the distance to the object. A timer prevents stopping of the depth clock until a predetermined delay after the first time. A speech synthesizer produces spoken numbers corresponding to data supplied to the speech synthesizer. Data corresponding to the content of the counter are supplied to the speech synthesizer. The system is safer than prior art systems as it does not need to be observed.