What is "tuning"?
"Tuning" is the adjustment of the tension of a piano's strings. There are physical laws that are followed, but tastes, custom, and tuning systems, as well as the instruments themselves, have varied from country to country through history. Most tuning systems have kept the unison and octave pure, but everything else - the number of notes to the octave, the distance between notes, and the sound of the harmonies - has varied. Pianos have around 200 strings under high tension. Moving them delicately into the correct tune is difficult and time-consuming enough that piano tuning evolved as a separate profession.
Why do pianos go out of tune?
One reason pianos go out of tune is that they are mostly made of wood, and wood swells and shrinks as the humidity changes. That happens to a greater degree when pianos are placed near doors or poorly insulated windows, or sit in a beam of direct sunlight. Some pianos are harder to tune than others, and with age may become un-tuneable. Some tuners are better than others, and a piano will go out of tune more quickly if the tuner lacks good technique. Finally, if a piano hasn't been tuned for a long time, the pitch may drop. In all of these cases, the piano will sound dissonant, particularly when used with other instruments.
If you're an engineer, physicist, or a person who thrives on details, may I recommend reading all about piano tuning in Wikipedia:
What if your piano sounds too harsh, or too soft?
If your piano is in tune but you still don't like the way it sounds, the problem could be voicing. Modern methods of piano manufacture often leave pianos sounding too loud and harsh once they've been "played in", but quite often there are quick, inexpensive ways to modify an unpleasant sound, or change it completely! That's called "voicing". Voicing means modifying the sound of the piano so it makes the best possible sound, according to the owner's preference. Voicing might mean making the whole piano or certain notes louder or softer. It might mean reshaping the felt hammers or changing the density of the felt to get a more singing tone.
The way the hammer strikes the string affects the sound. "Voicing" may be a major part of the remedy for a poor or uneven sound, but another part of the remedy may be putting it correct mechanical adjustment. This improves not just the touch, but affects the sound, too. Mechanical adjustment is called "regulation".
What is it called when a piano malfunctions or seems hard to play?
Pianos are machines! Inside them is a rather complicated wooden machine (called the "action"). For each key, there are numerous points of adjustment in the action, to compensate for wear, weather, and the compression of materials. There are many steps between not working at all and working perfectly. Technicians may recommend troubleshooting a specific problem, repairing parts that are worn out or broken, or "regulation". Regulation refers to adjusting the action so that it works the way it was designed to work. A piano that's been regulated allows the pianist to play with the greatest amount of dexterity, dynamic expression and control. A regulated piano minimizes fatigue and joint pain.
Troubleshooting and repairs:
It's best if I can get a description of any problems before I come to your home. That helps me schedule enough time, and have on hand what I need to fix it. To give an example: if a note keeps sounding after the key has been released, it could be a damper problem. Fixing it might involve replacement of the damper felt, or perhaps merely alignment of the damper felt to the strings or adjustment for the proper lift with the pedal. Accurate descriptions are most helpful! For a technician, "the note keeps sounding" is a much better description of a damper problem than "a key is sticking." To a technician, "a key is sticking" means the key does not come back up when it is released - a whole different scenario!
There can be structural problems from age, sun, or damp. There can be problems or noises in pedals, benches, soundboards, and case parts. Both cats and mice have been known to do bad things to pianos. So have toddlers. There can be decades of dirt, dust, and rust inside. Ivory keytops can be damaged or falling off. One reason I love my job is that I never know what I'm going to find!
How do people find me?
Angie's list, word-of-mouth referrals from satisfied customers, the Piano Technicians Guild website, google searches and my own website.