As wonderful as pianos are, one thing will probably always remain true about acoustic pianos: they go out of tune! Normal fluctuations in humidity within the home will usually put a piano out of tune to a small degree within days of a professional tuning. After six months to a year, a piano can be so far out of tune that it can be detrimental to a students progress. To a student, their piece simply doesn't sound right and they are not sure why. Their frustration level increases and their motivation to learn the piano decreases.
Pianos that have not been tuned for several years
can be so far out of tune that the piano can be physically damaged.
Pianos are built to have a specific string tension. After a few years,
pianos will often lose that tension and go flat. For every semitone
a piano goes flat, the overall string tension is reduced by 5000 lbs.
Putting that tension back onto a piano after several years can be a
tuning nightmare. Strings can break, tuning pins can loosen, even the
frame or soundboard can crack. In this case, the tuner must raise the
strings tension higher than their normal level and then let the piano
settle back to concert pitch (the ideal string tension). A second tuning
is almost always necessary. My flat rate for each tuning is $125.00.
However, if a piano needs to have its string tension restored, I will
have to do two tunings. I usually tune the piano again about a month
after the first tuning.