This is interesting... I agree with Ron's perception that the tuned unison "feels" or "is" (not sure which) apparently less loud than an un-tuned unison. I also hear a reduction in sustain, at least in the treble. So the question is, if the amplitude of a tuned unison can indeed be shown to be greater than a slightly out of tune unison via oscilloscope, what is causing the opposite perceived effect, at least to my ear? Thoughts: -some people's experience of out of tune-ness creates a discomfort which makes the sound seem louder than it is? -when there is beating is there periodic cancelling as well as periodic increase. The amount of energy available to those two strings doesn't change whether in tune or not, so is part of that available energy pumped disproportionally into the positive side of the beat? -geez, instruments like accordions are tuned with "wet" unisons purposely. Those suckers an cut through thick textures quite effectively. Tuned "dry" they have much less "power"...I'm not sure I buy that its solely a perception thing. Jim I The strength of the sound a string generates is in its amplitude (the > distance from peak-to-peak as measured with an oscilloscope). Two or three > wires tuned to exactly the same frequency will, being in phase, reinforce > each other and sound louder to the ear and on an oscilloscope. If one > string in a bichord is slightly off tune to the other then a heterodyne > effect is created where the off-tuned string actually detracts from the > amplitude of the combined string combination and can be heard as a "beating" > sound. The beating can be hardly noticeable (i.e., very slow) to rapid. > The beats are a result of the two string frequencies combining in a > non-linear medium (the strings themselves) and creating a difference > frequency (the beats) which is a difference of the two individual string > frequencies. This difference frequency actually acts as an out-of-phase > component and reduces the combined amplitude of the two individual strings, > thus making the overall amplitude less. The effect is even more pronounced > on a trichord. > > In actuality, though, tuning a bichord or trichord will result in an overall > increase in amplitude but it will be a bit less than if the two or three > strings were perfectly in tune (in phase). > > Tom -- Jim Ialeggio grandpianosolutions.com 978- 425-9026 Shirley, MA -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20101230/a5be824f/attachment.htm>
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