The repetition rates of audible sounds are correlated to the audio frequency values of tones. While the invention can be carried out by mechanical apparatus, the specific improvement disclosed utilizes electronic equipment for efficiency, effectiveness, accuracy and reliability. Electronic equipment produces audible tones and audible sounds. Manually operated controls select a tone or a sound, select an octave range for the tone or the sound and control the duration and repetition rate of the tone or the sound. A electroacoustic transducer connected to the controls produces the selected tone or sound in the controlled octave range at the controlled duration and repetition rate to relate pitch tonally and numerically to the repetition rate of pulse beats.