Bob, and all, > A cent is 1/1200 of an octave (100 cents = 1 equal tempered semione). Most books on musical acoustics > quote a threshold of 4 cents for human pitch discrimination. I don't remember what the basis is or whether anyone > has tested to see if those who claim they can do better really can.
I don't know if the books on musical acoustics have used tests for pitch discrimination, but I can say they have been made. My A.B. in psych (of many, many years ago) came from a "rat running" department. We made mechanical tests of all aspects of the human (and animal) senses. I don't remember the results for pitch discrimination (it is a variable skill among people), but the test was a pair of "pure" tones in sequence - and the choice of lower, higher or same. That eliminates the question of overtones or beats. It is not a musical discrimination, but a pure physical capability. One could probably find an "adept" at pitch discrimination who had no sense of sonance or dissonance. That is, in part, a matter of training and/or accustomization. And one could probably find a musician with less physical pitch discrimination, yet a "better ear" because of his understanding and experience. [BYW, I found out why I wasn't a great athlete. We tested raw reaction times by asking the subject to release a key on the flash of a light. My time to remove my finger from a button was .25 seconds, the same time it took our 225 pound football captain to jump off a keyed platform. He moved his entire body in the time it took me to move one finger, his finger time was .1 sec. ]. > Comma is usually used to refer to discrepencies in pitches. The main one you are concerned with is the > Pythagorean comma - 12 perfect 5ths and 7 perfect octaves "should" get you to the same note - but they > don't: 12 perfect 5ths get you about 23 cents higher (~1/4 semitone) than the seven octaves. > Temperament is the business of where to sweep the 23 cents under the rug. I love that last sentence Bob, it sums it up. Stewart has made a fine and brief description of the actual numbers, and one of value to those who aren't familiar with the concepts of cents and commas. But to take your analogy to the fullest I might say "how to spread those last 23 cents worth of dirt that the vacuum cleaner didn't pick up around the rug so your wife won't notice". But your sentence is briefer, and more to the point. Best, Jon
