At 9:10 AM -0400 8/2/02, Farrell wrote: >Why does a flute sound like a flute? Why does an obo sound like an >obo? Why does a guitar sound like a >guitar? And last, but certainly >not least, why does a piano sound like a piano? Why does Terry's voice sound like his instead of his wife's? The answer doesn't lie in the proportions of the lower eight or sixteen partials but in the entire spectrum of acoustical energy delivered by the particular instrument, as the human being plays it. >Does anyone have a simplistic explanation for what is the cause of >unique sounds/tones among various >instruments? If you play A4 at a >pitch of 440 Hz on any instument, you will hear the pitch of 400 >Hz. >But they will all sound different. (BTW, that's some wicked negative inharmonicity operating on that fundamental, and is that "obo" beginning with an "h" or ending with an "e", my Spelch-Ecker couldn't make up it mind. <g>) Your assumption that all these sounds are construction from the same materials, ie. periodic fluctuations (sine wave or other) in air pressure is a good one. In fact it's the basis behind the Fast Fourier Transform analysis which produces the 3D graphs of sound which we all swear by. (Fourier analysis assumes all vibrations are sine waves.) But as you understand sound production in any of these instruments and the complexity of the local variables involved, you realize that while one skilled violinist might be able to imitate the sound of another violinist, that violinist's skill is completely useless at imitating a piccolo or a xylophone, even just concentrating on the same note on the scale. Local variables include, for all wind instruments, the internal cavities (chest and throat) of the individual players, say for flutes whether the tubes are palladium or nickel-plated "mystery metal", for single reed instruments (clarinets/saxes) whether the mouthpiece is bakalite or steel.....You get the picture. As an aside, a classical saxophonist once told me that in his student days he made a saxophone out of cardboard (no holes or keys, just the tube) and had to conclude that 90% of the identity of the resulting sound came from the saxophone mouthpiece up at the top. >So I guess they all do something different to the soundwave that >reaches your ear. What is that >difference? How does a speaker >reproduce these differences of they only move in and out? In/out happens to be the speakers mode of production, as opposed to the high speed stuttering of a violin bow. As long as the sound system driving the speaker cone has a good electrical analog of the sound of a violin, the speakers' in/out will produce a good facsimile of a violin. Or xylophone or piccolo. Getting back to your voice compared to your wife's, Terry, part of the difference comes because you shave your face every day, where as she's shaving her legs. How that relates to timbre at a common pitch is unclear, but for the time being, I'd classify this observation as a local variable. Next? Bill Ballard RPT NH Chapter, P.T.G. "Never try to teach a pig to sing. It wastes time and annoys the pig." ...........Sign on the wall of a college voice teacher's studio. +++++++++++++++++++++
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