Tuning

Tuning is the most common service that pianos receive. It is a procedure of changing the tension of the piano strings so that they are in pitch to a given reference frequency (usually setting A4, the fifth A from the bottom of an 88 note keyboard to 440 Hz, or cycles per second), and adjusting the remaining notes on the piano to conform to a harmonically pleasing twelve tone scale of half-steps. This is a complicated description for a complicated process of setting a piano so that it sounds musically pleasing when pieces are performed in different keys. It is not as simple as setting each note (of which many have three strings per note) to its theoretical Hertz frequency, as this does not make the piano sound "in tune" with itself; music sounds harsh and dissonant. Pianos must be tuned relative to themselves, that is, so that intervals such as octaves, fifths and fourths sound tuned despite the fact that they may be different than mathematical scale frequencies. 

Pianos need tuning; they were designed for it. Once a year is the minimum that a piano should be tuned; twice a year is ideal. A regular tuning schedule will help the technician keep the piano sounding (see voicing) and playing (see regulation) in peak condition. Without regular tuning, pianos drop in pitch and require greater effort to keep them on pitch. Pianos that "never need tuning" in fact are never tuned, as all pianos require regular tuning. It is hard to judge "good" tuning in a piano if a person has become used to an out of tune instrument.

Regulation

Regulation is a connected series of procedures that align the parts of a piano action. Proper regulation of keys to action, and action to strings ensures that a piano is playing most efficiently. Pianos are regulated first in the factory after assembly, and can require additional regulation after being shipped to a dealer. Piano keys and actions were designed to be adjusted, as the parts are affected by wear and changes in humidity, and will change from their proper adjustments. Once in the home, the regulation of a piano is dependant on the amount of use that it receives. Constant playing will settle the levelling of the keys, changing the responsiveness of the action to the keys, and creating a different feel or touch to the player. A piano in poor regulation is hard to play, and the tone (see voicing) is also affected.

Regulation, like tuning , is a normal, ongoing service concern, and should be addressed with each tuning a piano receives. It is far simpler (and cheaper!) to correct small changes in regulation at each tuning than to perform a major regulation when the piano becomes difficult to play.

Voicing

Pianos are defined by their tone. Piano voicing is ensuring that the tone of the piano is consistent from note to note. Achieving a balanced sound, whether it is bright, medium, or mellow, is the ultimate aim in piano voicing. Unlike tuning, which deals primarily with adjusting the tension of the strings, voicing deals with the piano hammers and their relationship to the strings. 

Hammers are made of dense layers of wool felt that are wrapped and fastened to a wooden moulding. The density and tension of these felt layers determine the tonal quality of a note when the hammer hits the string. Hard hammers will give a brighter tone, where soft hammers give a mellower tone. 

Piano voicing is a process of manipulating the felt layers of the hammers through various means. Hardening hammers can be accomplished by: 1) filing away softer top layers of felt, 2) using heated hammer 'irons' to drive out moisture and increase density of the felt, or 3) using chemicals on the felt to harden the felt fibers. Softening hammers can be achieved by 1) using various needles on the hammers to release tension in the internal layers of felt, 2) introducing moisture into the felt through steam or water/alcohol mixtures, or 3) reversing chemical hardening procedures using solvents or thinners.

Voicing the hammers is dependant on the piano being in good regulation, with all the hammers hitting the strings evenly. Voicing is also dependant on the piano being in tune. Piano voicing changes as hammer felt changes, through playing, which flattens and grooves the felt, or aging, where the felt loses moisture and becomes hard and brittle.