buzzing on the mouthpiece...NO one agrees with me, EXCEPT...

[timothy42b]

I would assume that anyone - using a guitar pick, etc. - could replicate what I did and show themselves that the lips are vibrating independently of each other.

Would anyone who has been following this care to explain, why the razor or whatever would have interrupted the sound? I as yet do not understand what that experiment proved or disproved.

What I think he is saying is that he would be able to feel his lips touch the razor blade, not that it would interrupt the sound.

I'm one who has always believed that the lips close completely on every cycle. That is based on my readings in acoustics and those videos that show it, with trombone and trumpet players I think.

Bloke is pretty convinced it doesn't work that way for him. I'm wondering if the tuba air stream is at such a low pressure that the waving of the lips in the air stream can set up a buzz even without closing? while the same doesn't seem to happen on trombone and trumpet? Just thinking out loud. But then I have to answer how such a slow and low air flow can suck the lips toward and away from each other.

Maybe we could coat the razor blade or guitar pick with dye of some kind and check for marks on the lips. A charcoal pencil would work.

[timothy42b]

I just tried an experiment, buzzing and trying to insert the corner of a business card.

There's no way. Even the tip of it makes contact with both lips. That doesn't prove they close all the way, but I think they do. Well, mine do. Caveat: I tried the Bb and the F above the one bloke used, I don't usually buzz as low as that.

[Doug Elliott]

A thin strip of a business card has no effect when inserted during a buzz. The lips just close over it. Doesn't prove anything.

[timothy42b]

A thin strip of a business card has no effect when inserted during a buzz. The lips just close over it. Doesn't prove anything.

Right. I can still buzz with the strip in the "aperture." But there is resistance to moving it in or out, which probably means the lips are touching each other during the buzz, and that's what bloke disagrees with. Probably anyway.

[Donn]

What I think he is saying is that he would be able to feel his lips touch the razor blade, not that it would interrupt the sound.

But if his lips can't feel each other upon touching, would they feel the blade? Maybe, but it isn't obvious.

Just to make sure, I held a razor blade between my lips and tried it again.
My lips still arched (again, into the shape of a contrabassoon reed) and (well...) vibrated independently.
sure...There was a subtle change in the sound (air whistling past the razor blade), but everything worked the same.

I would assume that anyone - using a guitar pick, etc. - could replicate what I did and show themselves that the lips are vibrating independently of each other.

So let's say it is proved, that they vibrate independently. Would anyone have thought otherwise? If so, what is the nature of the interdependency of the lips, that might have been affected by the razor blade, and what would have been the outcome?

In other words, the experiment shows that the lips are independent, because the razor blade affects ______, and if they are dependent the result would be ______?

[ Note that "buzz" is not the same as playing. Has anyone claimed that you can "buzz" without lips touching? I don't think so. ]

[peterbas]

Here a link with videos with some academic background. You can see the lips touching but the time they're touching is very short compared to the time they're open. Look at a standing wave and see the small amount of time needed for change around zero (max speed)
https://www.youtube.com/watch?v=IaE2ALP ... eaLN8qi37H

But that is not what most people mean when they use the term "resistance". In electronics, impedance is resistance at a particular frequency, and that is the resistance that people are missing when they buzz a mouthpiece. In the frequency domain, where musical notes reside, we really should think about resistance in terms of impedance. Leland got a start on this with his word "resonance", which is the inverse of impedance, and resonance peaks when impedance is near zero. But zero impedance is also bad, because it would require so much airflow that we would be unable to sustain the note. In a resonant bugle, the only frequencies that resonate are harmonics of the fundamental frequency of the bugle. Other frequencies have high impedance (as opposed to mere resistance) and are attenuated. The reason the impedance is high is because the pulse bouncing back from the bell cancels out a pulse coming at the wrong time (because it is at the wrong frequency). That's why buzzing off-pitch undermines the sound--it kills importance harmonic resonance even if we are forceful enough to sustain the buzz.

Rick,
I think you're forgetting that brass instruments are closed pipes, you're discription is for open pipes (flute)
See the excellent website
http://newt.phys.unsw.edu.au/jw/brassacoustics.html

[Donn]

See the excellent website
http://newt.phys.unsw.edu.au/jw/brassacoustics.html

Hey thanks! that's quite apropos to the topic -

Playing softly and loudly

This simple picture already allows us to explain something about how the timbre changes when we go from playing softly to loudly. If we play softly, and especially if we play a high note softly, the lips don't move fast enough and don't have enough time to close completely. In this case we observe approximately sinusoidal vibration: the system is behaving like the linear mass-and-spring oscillator of physics texts. This means that the fundamental in the sound spectrum is strong, but that the higher harmonics are weak. This gives rise to a mellow timbre. Playing loudly, the lips do close, and may even close abruptly. This gives what physicists call clipping and nonlinear behaviour, which produces more high harmonics. As well as making the timbre brighter, adding more harmonics makes the sound louder as well, because the higher harmonics fall in the frequency range where our hearing is most sensitive (See hearing curves for details).

So it would seem, bloke is simply more mellow than the rest of you.

[Donn]

Those things are generating sound, directly (cymbal) or indirectly (guitar string) simply from the vibrating object; if the object's physical properties cause it to continue vibrating, it will continue to make sound.

Wind instruments don't really have any tone generating vibrating object, instead they have reeds/lips etc. that interact with an air stream that's resonating to a pitch. No air stream, no sound. Accordion reed for example - it's springy enough you can "twang" it, but that doesn't make an accordion sound at all. When the air stops, the sound dies.

[Doug Elliott]

Bassoon reeds don't touch?

From "Physical Forces at Work in Bassoon Reeds" by James B. Kopp
http://koppreeds.com/physicalforces.html#section6" target="_blank

In its first or static phase, the bassoon reed is at what a physicist would call atmospheric pressure. When we begin to blow air into a reed (during the initial transient), we raise the air pressure, causing the blades to “inflate,” or open further (second phase). Air begins to pass through the reed tube. Because the tube is narrower than the blades, the air accelerates, just as water forced through a hose nozzle accelerates. The upstream pressure, supplied by the player’s abdominal muscles, is above atmospheric, a physicist would say.

This is an instance of a Bernoulli effect, a physical force arising from a sudden narrowing of the air column: as an air column narrows, the downstream pressure decreases, and the result of this is that the air speed increases. The acceleration of air through the reed tube creates a suction (or negative pressure), which causes the blades to “deflate,” passing through the static position (third phase), until the tip closes (fourth phase)

[Donn]

Bassoon reeds don't touch?

They do. Saxophone would be more more like the account of brass embouchure above (from UNSW.) The reed usually beats against the mouthpiece, but played quietly and with good air support it may stay open, creating a "purer" tone.

[peterbas]

https://hal.inria.fr/file/index/docid/4 ... laying.pdf

On page 20 you can see the open close time of the lips. Total time is about 20 msec and thumb measured the time the lips are closed is about 1 msec.
You'll need a high speed camera to catch that moment, see p 17

I should publish or print/distribute an article with a set of diagrams, and what I believe I am observing will - then - also be viewed as science.

Sure you could if your article complies to the 'scientific method' it could revolutionize the knowledge about how brass instruments work.
But give it some time your geocentric model also needed more the thousand years to be corrected.

[Doug Elliott]

If a reed doesn't close during its vibration cycle, why would it be important for the facing to be flat across the tip of the reed, and have the curve that creates the opening?

If it doesn't need to seal, it could be any old shape.

[Donn]

*...and - if this is embraced as "truth", how could the reed tip movement be ONLY three millimeters, as the rebound surely flexes the reed tip back PAST it's at-rest position.

I believe that's why large tip openings (like .120) are generally expected to sound like they have larger "chamber" volume, so much more commonly seen in mouthpiece styles (like Berg Larsen for example) where the internal chamber is reduced with a "baffle." Because the generous reed travel is indeed somewhat symmetric, and thus expands the area of air "inside" the mouthpiece.

Anyway ... "breathtaking", etc.? Are you saying, the reed doesn't really oscillate over the whole tip opening? You know, the air going through there is under some pressure. I had problems for a while, combination of technique and too-soft reed, where upon unusually enthusiastic playing, the reed would close - and stay closed.

[Doug Elliott]

Strikes, seals, closes... all the same thing. You''re saying it doesn't do that.

[Donn]

absolutely. The reed tip oscillates over (well...under) the tip opening...
...so (rather than claiming that the reed tip strikes the tip opening of a clarinet or sax mouthpiece dozens-to-hundreds of times per second) you're now altering your claim to align with mine?

over
...
2. expressing passage or trajectory across

The reed oscillates within the area defined by the mouthpiece facing. As I have said several times and I believe furnished citations from other sources, it may or may not actually strike the facing, depending on the instrument (clarinet/saxophone), reed strength, playing technique etc.* Striking the facing ("beating") is not essential to the production of sound, it only changes the timbre. Just as with brass+lips, if the UNSW story is right.

[ * I don't know if anyone has been able to determine to what extent the reed beats or doesn't beat. Unlike double reeds, the gradual curve of that facing suggests that the reed might contact the facing along part of its length without closing all the way to the end. My sense is that what you hear is when it gets to the end and stays there during part of the cycle. Lips could be the same - maybe there's a range of not-fully closing that could be detected in the transition between soft and loud playing, if we had incredibly fine resolution film. In any case, I think the key point might be that it doesn't matter, until you get to the point where the lips stay together for part of the cycle, and then there will be a tonal effect. ]