An electronic entertainment device which allows an untrained vocalist or instrumentalist to easily synthesize an instrumental lead, and optionally, one or more harmonies, simultaneous with the lead, playing along with predefined background musical sequences. While the background parts to a song are being played by the device, or any outside musical player, the user plays the melody, or "lead", by humming, singing, whistling, or operating any tone-producing device, such as a musical instrument, into the device. The device then identifies the pitch, compares it with a table of allowable pitches, as dictated by predefined data associated with the background music, chooses an appropriate output tone, and drives a music synthesizer to play the chosen instrument at the determined pitch, in accordance with the allowable pitches. The note which is produced by the device is one which sounds pleasing in the context of the musical background. The device facilitates an active involvement in music expression without a need for well developed skills as a vocalist or instrumentalist.