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The other day, the piano tuner came to the semi-annual tuning of my piano (a Blüthner baby grand). I was not at the house when he did the tuning. When I got home, the piano was tuned in respect to itself but not according to the absolute pitch (about 15 cent down). I used the "Cleartune" Iphone app to determine that. This piano tuner has been tuning my piano for three years and is very professional.

Is this considered a tuning mistake? Is an absolute difference of 15 cent is even distinguishable by a human ear?

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You have used the same piano tuner for three years, kept the piano regularly tuned, and this is the first time it has been tuned lower? Or is this the first time you have checked it against an external source? –  200_success Apr 16 '12 at 22:42
@200_success I checked the two visit before the last visit , and this is the first time it was tuned lower. –  iddober Apr 17 '12 at 7:05
I can understand tuning it low if it was already flat, so as not to put too much stress on the frame all at once. However, if it was already close to standard pitch, that's just bizarre. I would ask your tuner to stop by to check it whenever he happens to be in the neighborhood. –  200_success Apr 17 '12 at 14:55
Which keys did you measure? Did you take stretched tuning into account? –  endolith Jul 7 '12 at 16:53
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4 Answers

up vote 12 down vote accepted

It's pretty common place to tune a piano lower as it gets older since that puts less mechanical force on the frame. However that should better be done by consulting the owner and then bite the bullet and tune it down a full half step (so you can still play with others by transposing).

15 cent close to the "just noticeable difference" or jnd but it can certainly be audible. This website has some audible example of a middle C at different rates of detune.

It's also possible that your iPhone's internal crystal is slightly out of whack. In order to build a good tuner you need a reasonably good reference clock and the IPhone hardware has no particular reason to have one with a tightly controlled center frequency.

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Good thinking about the crystal precision, but 15 cents off is too large for that. 15 cents at the 440 Hz A is an offset of around 4 Hz, that is 0.1 %. A crystal in the iPhone should be at worst +/- 20 parts per million (ppm), 0.1 % would be outrageous. That said, I wouldn't trust the writers of the app to give that level of precision, even if the hardware should. –  Gauthier Apr 13 '12 at 18:11
Playing with others isn't really an issue unless their tuning holds well, and it takes more than a few minutes to re-tune. Other than melodic percussion and recordings, there wouldn't be many instruments inside a house that would pose a problem. Guitar, string, and wind instruments all have to be tuned each time they're played (or in the case of wind instruments, when they're played with others) anyway, so having the piano 15 cent out isn't that big a deal. Still, bring it up with your piano tuner. –  MBraedley Apr 13 '12 at 23:14
@Gauthier: I wasn't implying that the clock drift itself is out of spec, but that at some point Apple switched vendors or parts with a slightly different nominal frequency (say for the CPU clock). They have no reason not to. –  Hilmar Apr 14 '12 at 15:48
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From the perspective of a piano tuner, 15cts is a huge descrepency. It must have been tuned that way on purpose. Probably because a piano that low would require a pitch raise (and thus an additional charge) to bring up to concert pitch. Since you weren't there, he/she probably decided to leave it where it was. I would always talk to the owner before leaving a piano anywhere but right at concert pitch.

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Did you measure at A above middle-C? (A4) The Cleartune app may not take the inharmonicity of your piano into account. Depending on how far away from that reference it is measured, you may see confusing results.

When I installed the professional tuning software called Tunelab on my iPhone and iPod Touch, it did not need calibration at all on either device when compared to the NIST analog standard. Spot-on, to the accuracy allowed by the calibration function of the software. I do not know if this is typical, but I suspect there is not that much variation between devices, at least not enough to be off by 15-cents at A4 (about 4 Hz).

Was there direct sunlight on the piano when you measured it? A tuner should call out environmental conditions that may affect your tuning stability. Temperature change is one way to get very rapid instability on your tuning.

A possible reason for "floating" pitch, since you say it is tuned twice a year, is if your piano has a relatively wide natural variation in pitch from low to high humidity seasons. Depending on the particular time of year, a tuner may not watch to "chase" the pitch up and down with the seasons. In this situation, I would try to recommend the best time of year to tune such that a piano would be close to pitch for as long as possible.

There are many variables, I would definitely ask your tuner what his intent was, describe how you took the measurements, and see what his response is.

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I highly recommend you do the following.

1) get a calibrated tuning fork and test one more time that your A 440 is off. So you are absolutely sure.

2) have a friendly chat with your tuner to discuss why this is off.

No one here can read minds. You really need to talk to your tuner about why he/she did not tune it the way you expected.

I also recommend that you are around the next time the tuner comes as this is a good time to discuss the condition and care of your piano. Have him check the action and check the hammers up close. My tuner removed the action last time and showed me what is breaking down. Although my studio grand is reaching 100 years old, it can still be tuned to concert pitch. I suppose because this was a quality build that it is aging well (Steinway).

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"Is this considered a tuning mistake? Is an absolute difference of 15 cent is even distinguishable by a human ear?" <--- That is the question. What does reading the OPs mind have to do with this? –  jadarnel27 Apr 13 '12 at 19:24
Mind reading refers to the piano tuner as no one here knows what he was thinking, what he perceived and why he made his choices. –  filzilla Apr 13 '12 at 19:34
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