If a keyboard has a harmony button, does that cause it to cause keys to repeat?
Not necessarily. It depends on the keyboard and how the manufacturer built the harmonizer function, but normally they work by adding an unplayed note to the melody line that is in harmony with the note you played. If you're playing chords with the left hand the harmony note will be selected according to the chord you're playing. Otherwise the note will be selected according to rules of harmonization that are programmed into the keyboard. The harmony note will sound nice usually and will be correct according to the rules, but it may or may not be the note you really wanted. That is, there can be a number of notes that will harmonize with the melody note and the computer inside the keyboard may pick a different one than you would have chosen yourself or that the composer of the song you're playing actually used.
