Electronic device that buzzes like human lips playing a brass instrument?

I'm not aware of any off-the-shelf device like that, but I'm not a musician, (not even a drummer).

What you're asking for sounds like a loudspeaker driver driven by some sort of variable oscillator.

If you're going to try to attach it to brass instruments you'll want feedback from the loudspeaker to the oscillator so it can auto-tune.

Can't see this working. Don't you need some sort of air-flow in addition to the rasping noise? Not going to get much audible power otherwise, I'd have thought.

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Almost certainly not. Lips, like all biological soft tissue, have a highly non-linear stress-strain curve (Young's modulus) - unlike almost all engineering materials. Muscle tension radically changes the spring constant of the tissue, which changes its resonant frequency - in line with the resonance of the trumpet or whatever.

I don't know of any machines or materials that implement this principle. Some no doubt exist, but the idea is definitely not mainstream.

Clifford Heath.

Well, whoopie cushions.

Reeds are also subject to acoustic resonances, though usually the player doesn't need to pinch much to manipulate harmonics, small holes on the resonant tube are used for that.

I'd think synthetic (silicone rubber?) lips with a nice smooth air pump and a servo jaw would get very close. The jaw and lips would be positioned in just such a way that the rubber is pulled tighter as the jaws close, giving a method to simulate tightening the embouchure. The air pump would have to be much more powerful, and variable pressure, to force through the resulting variable-resistance gap, but that might be an easier solution than making muscular lips. (Then again, one could stuff the rubber with muscle wire, or inflatable mesh muscles, for a truer reproduction, and then the lip tension would be independent of jaw pressure.)

Tim

What's wrong with a NE555 and a speaker?

ips do when playing a brass instrument? I.e. a membrane that oscillates but the propagation of the flapping/buzzing/vibrating is caused mechanically/e lectronically rather than using an air stream. The device would need to be adjustable - buzz at various pitches.

Well, sure; the mechanism in reed instruments and in lips is the same, it 's the abrupt closure of the airpath due to gas velocity and Bernoulli effect (which closes the a perture).

So, you want a latch that's set when some threshold is reached, and that un latches according to a settable 'relaxation time'. The latch output gates the input signal to form a buzzing output. Probably the 'threshold' should be AC-coupled. Yes, a '555 does have a suitable bunch of innards for doing this...

It won't respond to the resonance of the pipework, unless you use a speaker with dual voice coils and put one coil in the feedback path.

A blocking oscillator based around a dual coil speaker, or something more complex that can extract the back-emf of a single voice coil while driving it - a hybrid.

maybe this: +---------------+------+ | | | | | | | |7| | | -+- [1K0] [8] | | /| | | | | | | /|--[10k]---+ | +--< | ^ | | \|+---|-----|------+ | | | | / | / |100n=== [680] [8] :=========< | | | | \ | \ | | | | | +-----+------+ | | -+- --- ///

They don't "whoop" over four octaves, as lips can. Because lips have a Young's modulus that varies over a 10:1 ratio.

Air resonance is secondary. First you have to get the mass&spring constant into the right range.

What is the modulus range of silicone? I very much doubt it approaches the kind of ratios that are common with collagen variants. Probably not even 2:1

Collagen does this because it's a triple helix. When the molecule is stretched, the strands tighten against each other like a rope would.

We won't see truly life-like machines until we emulate that behaviour.

An overly simple case, I'm sure. :)

Come to think of it ...has anyone tried that? This is the only useful hit I see on Google, and it's just a couple seconds of action:

It's hardly an octave, so, hard to say.

Also not clear if it's like vocal fry (low pulse rate into a high frequency resonator). You'd need more like a didgeridoo to obtain more trumpet-like action, or a shorter or tighter rubber-flap thingy.

On a related note, I am aware of flatists, but I am not aware of anyone who can manipulate a (single) whoopee cushion into music.

Hmm, I was thinking just tension would do it, but that's fascinating. And, indeed, that would be very tricky to emulate! Thanks.

Tim

baloons can if you stretch the mouth laterally,

The way it's generally done in say linear predictive vocoders for speech compression in telephony applications is some kind of sawtooth wave for the voiced fricatives created by buzzing lips or larynx, and noise pulses for the unvoiced.

It's the most singular insight I've ever had into the divergence between "normal" mechanics and biomechanics. Almost everything about the way muscles, tendons and ligaments do what they do is predicated on collagen. By pre-tensioning muscles, we can set the spring constants to the desired range. I have no problem with us developing super-strong materials like carbon fibres - perhaps one day we'll even match spider silk! - but we need to work out how to make non-brittle structures with it, things with progressive response rather than linear. Once upon a time I hoped that a composite could replace the timbers used in e.g. making violins, but we aren't even within 20dB of that.

Most of the entire discipline of engineering has sought to produce structures than can be analysed, so we don't look too closely at the highly non-linear and non-uniform structures of biology - mainly because we can't mathematically analyse them. I'm sure that your control theory background gives you plenty of room to examine these ideas.

Yes, but that changes the geometry in a way that makes it incompatible with a trumpet mouthpiece. The point is to do it in a fixed geometry - that requires modifying the modulus.

Perhaps, if you are looking to experiment with electronic related things. start with a sawtooth driving filters...

A tape recorder with a pre-recorded buzz of the human lips

• variable motor speed?

Best regards, Piotr

You could try a small voice coil speaker driven with a square wave, but I expect that the acoustic source impedance would be pretty different--back pressure from the instrument will modify the speaker's response a lot more than it would a pair of lips.

That is, it isn't enough to make the same sound--you have to match the acoustic characteristics well enough.

Cheers

Phil Hobbs

maybe mould some silicone rubber lips, if the project is still live. You could probably buy them, but you might not appreciate the pose :)

NT

It's been a year...

It sounds a lot like he's asking for a car horn - he doesn't say that he wants the frequency electronically asjustable, so an electromechanical buzzer (with an adjustment screw) driving a diaphragm fits that spec.

something interesting might be possible usign a 2 coil speaker allowing feedback for the system to adjust to the resonance of the instrument.

Came up as new in GG on my phone, and I didn't notice the date.

Cheers

Phil Hobbs