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I've been able to find plenty of info about acoustic instruments that create sounds close to sine-waves, and I understand that sounds approximating square, triangle and sawtooth waves are produced by different types of acoustic instruments.

Are there any acoustic instruments that produce sounds very close to pure square, triangle or sawtooth waves? (The kind of artificial sounds produced by primitive electronic synthesis.)

I understand that these sounds are easily created by electronic synthesis, and why this is this case.

Suggestion of sounds produced using extended techniques are equally welcome (eg. "excess-pressure-grinds" on bowed strings; multi phonics on winds…), as are examples of mechanically produced (but acoustic!) sounds.

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Most of them :-). brass instruments are square waves (smoothed slightly by the instrument bore shape). Single reeds are close to triangle waves; bowed strings are sawtooth. –  Carl Witthoft Apr 23 at 19:57
    
Cheers, Carl. This makes sense to me, thinking about how the sounds are produced on these types of instruments (I read a bit online about how bows create a sawtooth type wave). Just wondered if anybody had examples that were particularly close to the artificiality of pure square, triangle and sawtooth waves, so recognisable from primitive sound synthesis. In fact I'll edit the question to make this clear... –  Bob Broadley Apr 23 at 20:05
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But only generally. None of those are pure square/tri/saw waves as a digital oscillator would make em. Their timbre changes -very- dramatically over the lifetime of a note. That's what makes them sound better. Your ear gets bored of a static sin wave =real= fast and starts ignoring it. The timbre changes in an acoustic instrument keep your ear (and brain) tuned in. –  Stephen Hazel Apr 23 at 21:07
    
Sure. So what about instruments more detached from the player? Ummm, organ, hurdy-gurdy, football rattle, or something invented by Busoni... –  Bob Broadley Apr 23 at 21:10
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Here is a useful link that describes in depth the acoustics of most orchestral instruments: Music Acoustics. Check the links on the left side to study the individual instruments. Very interesting reading! –  Hovercraft Full Of Eels Apr 23 at 21:44
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By itself, a bowed string produces something very close to a sawtooth waveform: the bow "catches" the string, pulls it a distance, then it releases rapidly returning back towards (or past) the equilibrium position, and then is caught again. This is described at the UNSW Music Acoustics site; note that the second figure down the page on the right is the speed of the string, the displacement of the string is close to sawtooth (or at least a very asymmetrical triangular wave in that model). However, the resulting sound coming out of a real stringed instrument will be modified by all of the various resonances in the instruments body.

The sound produced by free-reeds, e.g. accordion reeds, is pretty close to being an asymmetric square wave, essentially, one puff of air is emitted each time the reed flexes.

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Thanks for the link, looks great, plenty for me to get my teeth into and great that it has wave-form examples. –  Bob Broadley Apr 23 at 22:00
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