As I was tuning a piano in Sheffield last week, a customer asked a question about the ringing quality of an individual string on the piano. He had recognised what are know as false beats.

As most of you know, each note on the piano is sounded by the hammer hitting 3 strings which are tuned in unison to each other. A badly out of tune piano will have the recognisable ‘honky tonk’ sound, where . A well-tuned unison will sound practically beatless, although there is always some noise coming from each individual string which give the note a singing quality. Some strings, however, produce what are called ‘false beats’, where multiple beats are produced on a single string making one string sounds like a bad unison. Even though these false beats are a nightmare for the piano tuner (getting a unison in tune with fluttering harmonics ringing away is extremely difficult),  we have no other option that to try and work around it, as even electronic piano tuning devices don’t know what to make of such notes. As false beats best to spend extra time on strings with false beats to get the unison as well-tuned as possible. Replacing the string sometimes helps  but usually the problem is caused by bad design and the cheaper the piano the more false beats will be found (particularly in the high treble).

– Richard Lidster, Piano Tuner Sheffield.