Pitches in Pianos
If you haven't seen a tuning fork in action before, it's a real treat. Sound waves have so many unique properties that musicians and physicists alike are still learning about, but the science behind a tuning fork is fairly well established. Below is a YouTube video from the channel Jeri Crosby showcasing how they work; you hit the fork, and while holding it in the air you can barely hear anything, due to there being nothing but air to vibrate on. However, when touched to a surface, it resonates, and the more porous the surface the better the result.
I also find this video by the channel Zen Ezekin very interesting, as it showcases a particular aspect of resonance; as the sound waves travel, they will "activate" other similar sound waves. Because both tuning forks are tuned to the same pitch, one fork's resonance causes the other fork to also begin vibrating even though they aren't touching. This is actually a very important thing to consider while tuning a piano; one string tuned to middle C can quietly produce the sound of the C above it, as well as several other notes in the piano. This is called the partial system, but it is far too complicated to explain in a blog format. The sound theory rabbit hole goes very deep!
Because tuning forks are carefully manufactured, technicians can use them to tune any instrument, from guitars to violins and, importantly, pianos. The standardized pitch in today's world is A440, meaning that if you play middle A, or A4 to be exact, it should resonate more or less at 440 Hertz. Frequency of sound waves is really all tuning comes down to! While the traditional method of tuning a piano involves a tuning fork, there are many perfectly adequate technologies today to tune a piano without a tuning fork. With a tuning fork, one first tunes A4, then tunes A3 to where it has no conflicting sound waves with A4, and then based on your methodology, one can skip around the keyboard, counting "beats," which are conflicting sound waves, in order to get all of the intervals correct throughout the piano. This requires an immense understanding of music theory, tuning theory, the way that the piano reacts to a tuning, and years of practice.
Of course, tuning with an ETD, or electronic tuning device, still requires much knowledge of the piano as well. However, because you are measuring the pitch of each individual piano and then running it through a computer algorithm, you can more or less eliminate the need for counting beats while still producing an excellent tuning. This is because ETDs allow a tuner to start from the lowest note and move chromatically (from note-to-note without skipping any keys) all the way to the highest note. I personally use ETDs because I find the process of counting beats to be strenuous to my ear, and I would prefer to keep my hearing through my life!
The screenshots above are from the Cybertuner app, a professional piano tuning app that I use for my work. Good and Fair refer to the quality of the sample recording taken.
So, back to the A440 pitch: why is it standardized, and how do we interact with it? Older pianos were commonly tuned to A435 or another lower pitch because the piano manufacturers hadn't designed their pianos for higher string tension. German musician and inventor Johann Heinrich Scheibler recommended A440 all the way back in 1834, and it was adopted by German musicians that same year. Musician societies in America informally adopted A440 in 1926, and soon companies were manufacturing instruments with that pitch in mind. In 1936, it was officially recommended that the piano be tuned this way by the American Standards Association, and in 1955 was recommended by the International Organization for Standardization (formally adopted in 1975).
Why did we decide on A440? It's hard to pin down an exact reason, but my guess is that it was a compromise between orchestras and piano manufacturers. String instruments actually prefer to be a bit sharper than 440 Hz, sitting anywhere between 442-444 Hz, but the piano as it is currently designed has worse tuning stability at that pitch, with higher chance for string breakage to occur. It would be more expensive to produce a piano that can comfortably sit at A444, and so I think it's likely that pianos were raised from A435 to A440 to get closer to the stringed instruments, whereas they had to drop down to A440 for performances with a piano. Since virtually all music today is composed and performed at A440, I prefer to tune pianos to that pitch; otherwise, my client could sit at their piano to play along to a song only for their piano to be slightly out of tune on every note. The piano would be in tune with itself, with no audible beats, but since the song is at a higher pitch, it would never sound the same.
When it comes to alternate pitches, I don't find any of the arguments around any one pitch being "better for you" to be compelling, but I also personally have no issue with tuning a piano to an alternate pitch, usually A432, for my clients when requested. My only concern is keeping the piano's tuning stability intact while making sure that you are able to enjoy your piano in the way that seems best to you!
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