The pitch of the piano is its reference tone level. This is usually stated as the beginning note of the temperament system of tuning and carries a number indicating the frequency in cycles per second (c.p.s.) such as A=440 or C=523.3, and so on. A variety of tone generators, such as the pitch pipe or tuning fork, can be used to establish the pitch of the beginning note of the tuning system. Then, several methods to accomplish a reference octave can be used. All the notes remaining are then tuned to these (reference) notes.
The temperament is the system of interval relationships within the reference octave mentioned above. Using the beginning note as the starting point, a reference scale, otherwise known as the “temperament octave,” is completed using any one of several systems to establish the intervals in this sample scale of notes. Most commonly, the notes of the temperament octave are set so that each speaks a consistently diminutive frequency of the note just previous. This system is known as “equal temper.” Although it is the most widely accepted and friendly temperament in the modern music community, there are some 360 different systems in use. Most are historic variations which favor certain key signatures or interval patterns in order to produce the tone color requirements in literature specific performances.
Considering the physical characteristics of the piano, tuning is the aurally accurate distribution of the uneven pressure of all the strings pressing together on the instrument’s sounding board through its harmonic bridges. The piano is engineered so that this pressure arrangement across the entire scope of notes is consistent with a reasonable choice of pitch and temperament. When the instrument is in tune, the sounding board has been forced into a slightly truncated shape, or “crown,” forming the acoustic resonator which is responsible for the bell like tones we recognize as piano music. In relative time, the slow stretch of the strings causes the sounding board’s crown to change slightly and the instrument is “out of tune.” It is important to observe the tonal condition of your instrument at all times, and have it pitched, tempered, and tuned regularly by a qualified piano technician.