Piano, Organ, and Keyboard/question on pitch

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Question
Hi!
I recenty had my piano tuned by a professional tuner. But I am a bit confused. I have a an app on my phone which gives the pitch of certain sounds. When I play the key of A it says something like 435hz. It doesn't say 440hz. I am aware of other strings vibrating due to something called overtones but shouldn't it be 440hz? What is going on with my piano?
Doesn't piano tuners go by the exact pitch that a note should be? The standard is A=440 aftar all.

Answer
Yes, your piano should be A-440.  I question how recently it was tuned, and was there a pitch raise involved?

Actually, pianos can vary their pitch due to changes in temperature and humidity, as the strings are terminated on each end by an iron plate, which expands and contracts with temperature.  Typically this is not enough to make a substantial difference, as most pianos are kept within a small range of temperature extremes.  Humidity, however, is a different kettle of fish.  The strings are stretched across a wooden soundboard, and wood expands with moisture and contracts with dryness.  During the summer the relative humidity can average 85% depending on where you live, and in the winter with your heat on it can plummet to around 12%.  So, if you had your piano serviced to A-440 in the summer and now are running heat in your home making conditions dry you can expect the soundboard to have contracted enough to drop the pitch to A-435, which is about 20 cents (1/5 of a semitone).  That is pretty extreme, but it can happen.

Good luck!

Piano, Organ, and Keyboard

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William Rowland

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PLEASE NOTE! I do NOT give values of pianos OR dates! The piano service questions I can cover include general information about piano tuning: how often should a piano be tuned, what if a piano has been neglected, what is a pitch raise, how long does it take, how much should I expect to pay for service, and so forth. I can also provide information about common repairs and adjustments, such as keys that don't work, those that continue to sound after you have let off the key, how important is the regulation, can I change the tone of my piano, how can I get the keytops repaired/replaced, and so on. I DO NOT provide resale values of instruments for two reasons: first, a technician has to physically check out a unit in order to appraise its value accurately, and second, values vary widely from one part of the country to another. I also do not offer advice as to care of the piano case, as that is better left to woodworkers and cabinet makers. I also DO NOT provide information about the age of a piano, that info can be accessed at http://www.pianoatlas.com.

Experience

I have been a piano tuner/technician in the Midwestern USA since 1974, working with customers and music stores to provide service to their pianos. I do tuning and repairs and provide free estimates on my services and have an A+ rating with the Better Business Bureau.

Education/Credentials
Empire School of Piano Technology, 1973, Apprenticeship at Century Keyboards, Joplin, MO. Also I earned a Bachelor of Science degree in Computer Science at Missouri Southern State University in 1990.

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