Robert Estrin - piano expert

What is Stretch Tuning?

Learn the basis of the musical temperament

In this video, Robert talks about "stretch tuning", which is the basis of the musical temperament - the universally adapted tuning of the modern musical instruments.

Released on April 5, 2017

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DISCLAIMER: The views and the opinions expressed in this video are those of the author and do not necessarily reflect the views of Virtual Sheet Music and its employees.

Video Transcription

Hi, this is Robert Estrin. Welcome to Virtual Sheet Music and Today, a really fascinating subject, what is stretch tuning? Now when I describe what this is to you, you're going to be amazed, some things that you may not ever been aware of. Well, first we have to talk about, what is pitch? Pitch is actually the ability of your brain to count sound waves. When you hear an A like the orchestra tunes to A440, what that really means is there are 440 vibrations per second and we perceive that as the sound of A. If you double the frequencies you'll get a A an octave higher, 880 cycles per second, and this is what pitches really are about.

Now, there are tuners that can also measure these frequencies with absolute precision, even more precisely than the human ears are capable of hearing. But it goes much deeper than that. Because if you were to play with a tuner, and play perfectly in tune every octave, when you got to the higher octaves, would sound flat even though they'd register perfect on the tuner. The proof of this is if a violin were playing in the very high register, or a piccolo in the orchestra, if they were to play dead center to a tuner with absolute perfect precision, it would sound hideously out of tune. Now how can this be? Well the fact of the matter is, our ears are not perfect. Our ears tend to hear flat in the high register. So in order for it to be perceived as being in tune, the octaves have to be stretched bigger than the doubling of frequencies, which is mathematically perfect. Our ears are not perfect. And this is what stretch tuning is about.

So when a piano tuner tunes a piano, for example, they don't just tune perfectly because if they did it would sound out of tune, and they know how to finesse the pitch just enough to make it sound right to the human ears. There's actually even more to making a piano sound in tune than just stretch tuning, but that's a subject for another video. So remember, you can depend upon tuners only to an extent. Ultimately, you have to use your ears. That's the final judge. Thanks so much for joining me. Once again, Robert Estrin here, and
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Comments, Questions, Requests:

Eddie on December 27, 2017 @2:41 am PST
I have a problem with pitch perception. All is well until about the last 2 octaves at the top end of the keyboard. If I block one ear and play a note, then block the other ear and play the same note, I hear a note that is of a different pitch. I don't mean the note out of tune, it is different by as much as a third or fourth. I have learnt to ignore the "wrong" notes my ears are telling me because I can SEE they are right .... if you see what I mean.
I have often wondered if this is more common than I think as it's only people like ourselves that would become aware of it. I do have a moderate hearing loss and it could be a side effect of that.
So, would any of your readers like to try this little experiment for me ? See what we come up with.
Thank you.
Robert - host, on December 27, 2017 @12:14 pm PST
I have not heard of this problem before. This is more of a medical issue than a musical question. I would consult a doctor.
Dan VD on February 27, 2019 @5:36 am PST
Half a step is the most I can muster doing that, with the same note on different octaves, even that is a little disturbing as I have trained myself to try to ignore the difference and compensate for environmental and perception differences. As Robert suggested, it maybe a medical issue.
Eddie Cocks on March 6, 2019 @2:50 pm PST
Hi, Dan VD. Sorry I'm so long getting back to you. Yes, I have a hearing loss at the high frequencies. A lot of people do these days but only musicians and those interest in music would possibly notice that pitch perception has gone with it. I'm OK around the bottom to the middle of the keyboard but up towards the top 2 octaves I encounter this problem. Like, if some-one played a familiar tune on a piccalo, I wouldn't be able to name it because all the notes would be "wrong" - for me that is. I was told by ENT consultant that my loss was due to hearing damage. I played in a band for about 35 years, 3 times a week. I also have tinnutis which started when I first noticed I wasn't hearing properly. My post on this site was an attempt to see if there were other players out there with the same condition. I was hoping that others would join in the test as hearing loss is common amongst musicians who play professionally or on a regular basis. However, yours is the only response I've had. Try listening to a flute at the top end of the range, see if you have the same difficulty that I have.
Michael Prozonic * VSM MEMBER * on November 22, 2017 @3:00 pm PST
It is not only our ear’s perception. If this were the case, all pianos would use the same amount of ‘stretch’ in the tuning. The laws of physics come in to play. Large concert grands have almost zero stretch while small consoles have severe ‘bends’ in the tuning curves at both ends, the higher registers going sharp and the lower end bending quite flat.
Also, no piano is ever perfectly tuned because the calculated frequency from one note to the next is actually an irrational number but as they say…close enough for jazz
Fulvia * VSM MEMBER * on April 6, 2017 @5:22 pm PST
I seem to have an issue with the lower octaves after my piano get tuned, to me they sound a bit higher than they should. It that also due to my own hearing?
Robert Estrin - host, on April 7, 2017 @12:12 pm PST
Sometimes with smaller pianos, the lower notes are difficult to deal with. Short bass strings have very strong overtones which may conflict with the fundamental pitch of higher notes making them sound out of tune even if they are in tune. A good tuner has to find compromises that make pianos sound good when dealing with these issues.

Here is an article and video which discusses the overtone series:
Michael Prozonic * VSM MEMBER * on November 22, 2017 @3:09 pm PST
If the technician who is tuning your piano is using a meter that automatically compensates for stretch tuning, he may be choosing the wrong stretch file. For example, he/she may be using a file for a large grand piano when you have an upright console. The amount of stretch is dramatically different. Or, perhaps he/she is using a tuner that does not calculate the stretch tuning at all.
On the other hand, if he/she is not using a meter and only tuning by ear they may be inexperienced. I hope you have communicated your issues with him (or her). You deserve satisfaction. Have you tried using a different service provider?
Nigel Cockman * VSM MEMBER * on April 5, 2017 @3:07 am PST
Thanks, Robert, another of your fascinating musical insights. Keep 'em coming!!!!
Nigel (UK)
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