[CAUT] Sacrifice (was tuners- technology)

[Ed Sutton]

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It would be worth remembering our discussion of temperature and pitch change when doing such an experiment.  Temperature changes induced by mutes, breathing, test equipment  or HVAC could produce such a small change in pitch.

ES


----- Original Message ----- 
From: Fred Sturm 
To: College and University Technicians
Sent: 3/3/2005 8:20:54 PM 
Subject: Re: [CAUT] Sacrifice (was tuners- technology)


On 3/2/05 8:31 AM, "Wimblees@aol.com" <Wimblees@aol.com> wrote:


Doing unison tuning by ear is described best by Virgil Smith. He says that the human computer can analyze the beats much better than the ETD. This is evident when tuning octaves. As he put it. "...octaves were right on when only one string of the upper octave was sounding, but was flat when all three strings were sounding".


    Yes, this is what Virgil says. That a unison goes flat overall when it is tuned (ie, if one string is tuned “perfectly,” when the other two are tuned to it, the overall pitch of the unison will be flat of where the originally tuned string was). And about nine years ago Jim Coleman confirmed this claim through measurements he made with a new RCT (RCT had just come out). I questioned Jim when he asserted he had made such measurements, as I had been unable to measure this phenomenon with my newly acquired SAT. Jim shared his data (I think this discussion was on Pianotech), explaining in some detail his methodology. Bottom line: through careful measurement he had confirmed that a tuned unison was between 0.1 and 0.2 cents flat of the average pitches of the three individual strings. In his experiment he had tuned each of the strings to within a measured tolerance of 0.1 cents of one another.
    I more or less accepted that at the time, thinking that RCT was perhaps more precise than SAT, hence you could read such a small effect using SAT, but I had to say that a difference of such a small magnitude was not going to be significant in the actual tuning of a piano. My own take being that Virgil was using this purported “fact” to justify stretching octaves. Remember he was asserting at the time (he has since recanted) that he tuned by listening to the beat between the fundamentals of the two notes of an octave, and made that utterly beatless. He also said (and wrote) that this produced pure and beatless triple and quadruple octaves.
    Your mentioning this unison/octave “apparent phenomenon” led me to be curious. Having an RCT of my own now, I decided to try to duplicate Jim Coleman’s experiment. First step is to tune each string of a unison within a measured tolerance of 0.1 cents – not a real easy task. Among other things, it is difficult to get repeated readings for a single string that are within 0.1 cents of one another. It requires playing at an utterly consistent level of volume. To have any credibility at all, one needs to be able to do at least three sample readings of each string, and have all of them be within 0.1 cents of one another.
    But, yes, I was able to do this, and proceeded to read the unison, with the same care and the same number of samples. And then I went back and repeated every step (re-measuring each string individually, etc). My results: I did not confirm Jim’s data. I found what I consider to be completely random results. Sometimes the three strings played together would be flat, sometimes sharp, sometimes the same. I am by no means saying that Jim did anything but a very careful and credible job, as I know him to be a very careful and utterly honest person. But my results were, shall we say, varied to such a degree as to lead me to believe that it would need a great number of repetitions of the experiment to persuade me that there was any measurable difference between the pitch of three strings sounding together and the pitches of the individual strings. 
    I realize that Virgil has taught this in classes, and that he has demonstrated, and that people have been persuaded by listening to his demonstrations. I suggest that it is quite possible that, in many instances, they heard what they thought they did. First, it is next to impossible to tune a unison within a tolerance of 0.1 cents, and I would say that it is utterly impossible without the use of a machine. It’s a problem of resolution – 0.1 cents is at the threshold of where a pitch produced by a piano string can be measured. They just don’t produce pitch that clearly defined. Variance in volume, and not that large a variance, will change pitch more than that.
    So my explanation of “how it works” in Virgil’s demonstrations is that, in fact, the unison tuned is not “absolutely perfect.” That one of the strings is likely to be, say 0.3 to 0.5 cents flat of the originally tuned string. And that the aural resolution of the pitch of three strings of slightly different pitches will be affected by the factor of phasing (phenomenon where strings will tend to phase with one another, locking their pitches to one another just like PitchLock does), so that it is quite possible that the perceived (and measured) pitch of the entire unison would be lower than the original string, because of one string having a lower pitch. And the unison might sound very clean. A unison within a tolerance of 0.5 cents generally sounds “perfect” to most everybody. But I know most if not all of us can hear a difference of 0.5 cents in context of octaves, M3s and many other intervals.
    At any rate, I would take Virgil’s assertion with a very large pinch of salt. Maybe there’s some truth in there somewhere, but it isn’t what I would give the status of a fact.
Regards,
Fred Sturm
University of New Mexico 
PS I would be interested in hearing the results of anyone else who replicates the described experiment.

     
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