The most basic service required to maintain a piano is to have it tuned regularly. Exactly how regular depends on a variety of factors such as the frequency and level of play, changes in humidity and whether the instrument is moved from one location to another. A standard tuning on a regular basis is an important step in maintaining a piano’s musical appeal and value.
A tuning once a year is the absolute minimum recommendation. Waiting longer than a year between tunings can invite problems down the road, not to mention the need for a Pitch Adjustment when the next service appointment is scheduled.
A more advisable frequency of tunings is twice a year, or every six months. Most professionals would suggest to time each tuning so that they occur a couple of weeks after each change in the climate (that is, when the heat or air conditioner is turned on and then later when turned off).
Tuning the piano only when it “sounds” bad usually means that too much time has passed and instead of a slightly out of tune piano, it sounds offensive to the ear. Tunings should not be delayed until the piano “sounds” bad. A professional technician makes a general inspection when conducting a regular tuning and this review can help spot troublesome issues when they are only minor repairs.
The Tuning Process
The process of tuning a piano involves first setting the pitch or frequency of one note to a standard. Usually, the note is “A” above middle “C” (also called A4) and the standard frequency is 440 hertz. The note A4 tuned to this standard is therefore called A440.
Tuning the standard piano so that a musician can play in all the different tonalities that we recognized in music involves a compromise in the pitches assigned to each key. This is due to the true acoustical properties of musical tone and the need to arrange those musical tones neatly on a standard keyboard layout with white and black keys. Most pianos and other keyboard instruments these days are tuned in a manner called Equal Temperament. When someone wants a piano tuned today this is what they are really requesting, even if they don’t know exactly what it means.
Pianos can also be tuned in a manner that is not Equal Temperament. These alternate tuning arrangements are called Historical Temperaments. Before about the beginning of the 20th century, there was no scientific way to create a true Equal Temperament. Therefore, musicians and tuners prior to the 20th century utilized other Historical Temperaments to tune their instruments. While Equal Temperament is the standard used today, there has been a resurging interest in Historical Temperaments.
After setting one pitch of the piano (A440, for example), the next step involves “Setting the Temperament.” The temperament is set for the notes spanning the interval of an octave or a tenth in the middle of the keyboard. Starting with the first standard pitch, each note is tuned according to acoustical properties and in relation to each other.
Once the temperament is set for the notes in the middle of the keyboard, the rest of the notes on the piano are tuned. They are tuned by building on the temperament and progressing both up and down the keyboard.
Another phenomenon that piano technicians must account for in this process is called “inharmonicity.” This occurs due to densities of the piano wire and causes specific frequencies of notes to “stretch” slightly outside of their scientific values. Because every piano incurs this a little differently, it is true to say that every piano is uniquely tuned and no two pianos are tuned exactly alike.