Abstract: A method and apparatus that enables tuning a piano to exact equal temperament includes beat time template generator. The beat time template generator is provided a fundamental key describing the fixed pitch the reference key is tuned and a secondary key to be tuned. The beat time template generator determines all the harmonics of the fundamental key and the secondary key. A difference beat frequency for all the harmonics is calculated for the fundamental key and secondary key and one beat time is selected as a reference beat time template signal. The reference beat time template signal is then transferred to a speaker for reproduction. A piano tuner then adjusts the strings of the secondary key such that when the fundamental key and the secondary key are struck simultaneously, the beat time of the struck keys is identical to the reference beat time template signal from the beat time template generator.