What is Piano Tuning?
Piano tuning is the adjustment of the tension of each string in the piano to set its optimal pitch. Increasing the tension of a strings causes its pitch to rise while lowering its tension causes the pitch to drop. Though (most) pianos have 88 keys, they typically have over 200 strings. Most notes actually have three strings, while the lowest notes have either one or two strings per note. A tuning typically takes approximately 1.5 to 2 hours.
A piano needs to be very close to standard pitch (A440) before a fine tuning can be done. When the pitch level of a piano is changed by more than 3 or 4 cents (100 cents are in a half step), the change in tension causes tuning instability. As the pitch level is altered, the strings that are adjusted early in the tuning process will change as subsequent strings are also adjusted. So, when the pitch level of a piano is very far off from standard pitch (A440), a quick rough tuning is necessary before a stable fine tuning can be done. This rough tuning is typically referred to as a pitch raise or a pitch correction.
When a piano is significantly off from standard pitch (more than 25 cents flat or sharp), more than one rough tuning is necessary to provide a tuning exactly at standard pitch. I can help you decide if multiple rough tunings are necessary, based on how you will be using the piano. Your piano should be maintained close to standard pitch. It will sound its best at standard pitch, as it was designed with standard pitch in mind. However, if your piano requires a significant pitch correction, it may make sense to make the correction over the course of multiple regular tunings.
What makes a piano go out of tune?
Shifts in tempature and humidity, as well as use and time all affect tuning stability.
Pianos go out of tune primarily due to changes in humidity. Since pianos are mostly made of wood, they absorb moisture from the air or release moisture into the air until an equilibrium is reached. When wood absorbs moisture from humid air it expands and changes dimension. Whereas, when wood releases moisture into dry air, it contracts. You might have noticed this change if you have ever observed wood floors through the seasons. In the winter, when the air is dry from heating, the wooden slats get slightly smaller, while the cracks between the wooden slats grow bigger, causing a gap to appear. The opposite is true in the summer. As the slats expand with moisture, the gap disappears or grows smaller. This is the same phenomenon that causes doors or windows to stick in the summer, but then free up in the winter.
These same changes in the dimensions of the wood in your piano cause it to go out of tune. Specifically, it is changes in the wooden soundboard that cause a piano’s pitch level to change. When your piano is exposed to the dry air in winter, it goes flat, the pitch of the strings lowers. The opposite is true in the summer when moist humid air causes the pitch level to rise, your piano goes sharp. These alterations in pitch don’t always happen evenly throughout the piano. They tend to be most pronounced in the tenor and lower treble. Since these changes don’t happen evenly, we perceive the piano as out of tune.
The humidity level in your home fluctuates most dramatically because of heating. In the winter, your furnace heats the air and dries it out. There is a sudden dramatic change in the humidity level in your home, when you first begin heating in the late fall or early winter. Thus the tuning of your piano will change noticeably during this transition into the winter heating season, as your piano goes flat. Again, in the spring when you stop heating, the air in your home is no longer being artificially dried by your furnace. Then the humidity level will rise and the tuning of your piano will noticeably change once again, as it goes sharp. So your piano will go through two distinct cycles each year, with dramatic changes in the tuning of your piano taking place at the beginning and end of the heating season.
Use, temperature, and time also affect tuning stability. Heavy playing can cause changes in the tuning. However, the better the tuner and the more frequently a piano is tuned, the less playing will cause changes in the tuning. Temperature shifts also cause the pitch level of a piano to change, however, with modest alterations this usually happens fairly evenly across the piano, so the relative tuning may not be significantly affected. Temperature changes during a tuning are problematic though, and a piano should be tuned at the same temperature at which it will be used.
Finally, time also has a gradual effect on tuning stability. Piano strings are set at a very high tension. That tension represents potential energy that wants to dissipate. As it dissipates over time, the pitch level drops and the piano goes out of tune. So, even without use and in a stable environment, pianos should be serviced regularly.
How often should I have my piano tuned?
Piano tuning is primarily for the player and the listener. If your piano is in used, I recommend tuning it at least twice a year. This will facilitate both proper musical development of the ear and the most enjoyment of the instrument. (Additionally I have frequently had customers remark that their piano is more fun to play following a tuning!) Students who are practicing on an out of tune instrument are more likely to become frustrated and to quit. Regular tuning also allows your tuner to catch and correct any problems with the instrument early on.
As previously discussed in the ‘What makes a piano go out of tune?’ section above, the tuning of your piano will change dramatically about twice a year, corresponding with the beginning and end of the heating season. Tuning your piano twice a year will keep it reasonably well tuned throughout the changing seasons. Music professionals, serious players, and institutions will usually have their pianos tuned even more frequently though.
On the other hand, if your piano is not in use, I don’t believe it is necessary to have your piano tuned quite as regularly. A piano will tend to drop in pitch over time. Although, if you wait too long, there could be an additional expense for extra tuning when you decide to have the piano serviced, but a lack of tuning will not damage the instrument as some tuners say. I recommend tuning a piano that is not being used every 2-3 years, or right before you know that it is going to be used (e.g. when your child is coming home from college for a holiday break).