An electronic device that receives a signal indicative of the sound made my a musical instrument in order to determine the instantaneous rate of play of melodic notes on that instrument in terms of notes played per second and display the rate in real time via a display. The regularity of the musician's rate of play is further indicated by the stability of the display reading. Individual sustained melodic notes are identified utilizing differential capacitance and circuit delay time constants to generate a voltage differential in response to a step signal. The device is also selectively operable as a conventional metronome to provide an exemplary sound cue to the musician corresponding to a given number of notes per second and convertible by a switch or foot pedal to monitor the musicians rate of play as he tries to match the demonstrated rate.