Tuning a Piano
How often should a piano be tuned?
This is the most common question people as about their piano. (Often it is the only thing they ask!)
How frequently a piano "needs" to be tuned depends on the tuning criteria of the person playing it, what the piano will be used for, the environment the piano is in, whether the piano has brand new strings (a new or restrung piano), and of course, how much money the owner or performer wants to spend on tunings.
At one extreme, pianos used for professional performances are usually tuned before every performance. Clearly, that is not the standard for most pianos.
The pitch of the strings on a piano change very, very gradually, and the rate of change is not consistent across the whole piano. These changes are happening all the time, and the will happen whether the piano is played or not. Because the change in pitch happens so gradually, the owner may not notice that the piano is out of tune until it is extremely out of tune. A tuning on a piano that is extremely out of tune will not be as stable as a tuning on a piano that was close to being in tune to begin with.
In addition to the strings not staying in tune with each other, over time the entire piano gradually drops in pitch until over several years, the whole piano is "flat" - below the pitch at which other instruments can tune to it. More information about this is on the A = 440 page.
Pianos in the home, church, school
After the first year of a new or restrung piano's life, when the wire has stabilized, all the major piano manufacturers recommend that pianos be tuned twice a year. This is because changes in humidity and in temperature are the main things that cause the piano to go out of tune, and humidity and temperature change with the seasons. During 12 months, the piano has usually gone through 4 cycles of change. Unfortunately, different sections of the piano change in pitch to varying degrees. The entire piano does not rise and fall in pitch together, so the piano sounds "out of tune with itself".
I find that in southern Oregon, where temperature changes are not as extreme as in some other geographic locations, one tuning per year is often adequate for the piano to be "enough in tune" for the typical piano in the home where family members play for their own enjoyment or are taking piano lessons. Music teachers and serious musicians will probably want their pianos tuned twice a year. If the ambient humidity or temperature is constantly changing, as in a school or church, the piano may need more frequent tunings.
Allowing a piano to go much more than a year without being tuned means that the entire piano gradually drops in pitch until over several years, the whole piano is "flat" - below the pitch at which other instruments can tune to it. More information about this is on the A = 440 page.
New or restrung pianos
New piano wire is extremely elastic. Even tho a new or restrung piano is tuned many many times before it is delivered to its home, the wire is still "stretching out". New or restrung pianos need to be tuned three to four times during the first year, at which point the wire will have reached a point of stability in tuning.
Concert tuning
Professional musicians such as those who appear at Britt or the Craterian have contracted with the venue to have the piano they are using tuned at least once before their performance. Concert tunings are ideally scheduled as close to the performance as possible. In some cases, the piano is tuned early in the day, before a sound check or rehearsal, and then "touched up" before the performance.
Ideally, the piano will be in exactly the location in which it will be played before it is tuned, and will be permanently housed on a piano dolly. Changes like moving the piano from indoors to outdoors, ambient temperature and humidity, direct sunlight, and stage lights all affect the tuning. The more of these variables that can be controlled, the more stable the tuning will be. Even pushing a piano around on a stage can affect the tuning - more so if it is not on a dolly.