What is a pitch correction?

And why does my piano need one?

Picture a scenario that many piano owners experience: It’s been a few years since your piano was tuned. You fell out of practice, life gets busy, maybe you inherited the piano from your grandmother, or bought it from your neighbor. In any case, it’s been years since it was last tuned and it’s hard to call the sounds coming out of it “music” right now. You call your technician and after some inspection they tell you “it needs a pitch correction.” What does that mean?

Pianos go out of tune whether they’re played or not. You can check out my other article on why they go out of tune if you’re curious. Over time the strings lose tension and the pitch goes down. When you call your technician for a regular tuning visit, they should be tuning the piano to A440 every time to help fight this perpetual drift flat. If it’s been too long, the piano may be too flat to fine tune.

Each string holds approximately 160lbs/ft of tension. This varies by piano but it’s a decent benchmark. Multiply that by about 250 strings on the average piano and you have a massive amount of tension. As your technician brings each string up to tension, the increased tension on the soundboard and plate will cause the surrounding strings to go flat. By the end of a tuning, the piano will have sunk about 30% below the target pitch. So then it must be tuned again. Technicians joke that “to tune a piano you must first tune the piano”.

If your piano started out with A4 at 438hz, and it gets tuned to 440.2hz, it will settle pretty gracefully to 440hz by the end of the tuning. Not a big deal, a good technician will do a touchup pass at the end and everything will sound great. If we start out at 435hz or lower we can expect the piano to be pretty temperamental and will almost certainly need to be tuned twice.

Unfortunately, after a pitch correction you can also expect your piano to go out of tune a little faster than normal. The steel strings need to stretch and settle around the contact points at the bridge, plate, and tuning pins. Having your piano tuned regularly by the same technician is an exceptionally good strategy to cultivate tuning stability.

But why A440? There are a lot of reasons A440 is important. If you’re playing against recordings or with other musicians, being at the correct pitch matters so that the other musicians can tune to the piano. The piano also sounds and functions differently at the correct pitch. If the tension is too low, the strings will be too loose, increasing hammer to string contact time during play, and making the tone sound dull or muddy. Ultimately this isn’t fatal and it’s okay to refuse a pitch correction if you understand the musical consequences of the decision. A good technician will always advocate for making your piano sound the best it can, but will respect your decisions about the care and maintenance of your instrument.