What makes the sound?

[Stryk]

How does a tuba (or other brass instrument) make a sound?

Is it because it is simply amplifying the buzz of the lips? (this is what I always believed and taught)

OR

Is it the because the air traveling through the horn actually makes the sound and causes sympathetic vibrations in the lips?

Physicists and players like Renold Shilke say it is the latter: John Harbaugh explains

[iiipopes]

The simple answer is to ask Gilbert Spiteri of K&G mouthpieces, who has an engineering degree, and who uses his degree to design and build mouthpieces according to accepted principals of physics. Not myth, not derivatives of traditional designs, or anything else. Physics.

The answer without all the math is that when you form an embouchure and blow air through it, that is an application of Bernoulli's principal. As the air goes through the mouthpiece, pressure drops, the lips come together. This actually slows the air so that pressure increases and the lips separate to where they were. Depending on the embouchure, this rapid back and forth create pulses which we call pitch. This happens whether you use a mouthpiece or simply buzz your lips.

The function of the mouthpiece, therefore, is to channel the air and these pulses into the horn. Once the air flow clears the mouthpiece throat and expands into the horn, velocity of the airflow drops to essentially zero, kind of like a river emptying into a larger body of water, creating the delta when suspended particulate drops out of the stream. This sets up the resonances we call pitch and tone through static fluid dynamics. Watch a bobber in a lake. When you throw a rock in, creating waves, the bobber will bounce up and down on the waves, but really doesn't travel laterally. Those are the nodes and antinodes in the horn that are controlled by the valves changing the effective length of the horn for each pitch of each overtone series.

"Stuffiness" or "Free-blowing" is usually a function of something, whether it be a tubing turn, brace positioning, etc., that either impedes an antinode, or stays out of the way, depending on the horn and its construction.

[tadawson]

The buzz of the lips is "exciting" the resonant length of the horn to produce a certain note (determined by valves, etc) and the resonances of the horn, brass, etc. determine to coloration and overall sound of the note played, so it's a combination . . . Just blowing air into the horn gives nothing, and just the lip buzz does not produce the instruments full tone.

[Mary Ann]

It took me a long time to realize that the people who say "it's the size of the hole in your face" were right. Brass suddenly became easy; the only strength I need (other than to be the Air Bellows) is to maintain that hole's shape. I'm sure my lips vibrate, but I'm not buzzing them.

[bloke]

It took me a long time to realize that the people who say "it's the size of the hole in your face" were right. Brass suddenly became easy; the only strength I need (other than to be the Air Bellows) is to maintain that hole's shape. I'm sure my lips vibrate, but I'm not buzzing them.

smart person ↑

[iiipopes]

It took me a long time to realize that the people who say "it's the size of the hole in your face" were right. Brass suddenly became easy; the only strength I need (other than to be the Air Bellows) is to maintain that hole's shape. I'm sure my lips vibrate, but I'm not buzzing them.

You're right. You are really not buzzing them. Again, to review Bernoulli's principal, when you blow air through the embouchure, velocity increases and the pressure decreases. This causes the lips to come together. As they come together, airflow is restricted and pressure increases. When pressure increases, the lips are forced back apart to their original position by the air pressure. That's what we call breath support. Then the process repeats. It is the control of the embouchure that makes the process repeatable, or in physics terms simple harmonic motion, which we call supporting and producing pitch.

[bloke]

Y'all are going to trigger the people who believe that a clarinet reed is actually thumping against the tip of the mouthpiece, the blades of a bassoon reed actually hit each other at the tip over and over, and the piece of spring steel in a jaw harp is actually somehow hitting against the supporting frame.

Everything is a percussion instrument !!!

[Mary Ann]

Oh I can tell you when the two sides of the tip an oboe reed hit each other -- it's when you try to play oboe right after you play horn, you just blow the thing shut, and it won't play at all!

[bloke]

Anyone who glanced at my bass saxophone thread in the repair forum knows that I have an instrument that I am just about ready to finish restoring so I can see about becoming more proficient on saxophone, and obviously I'm only interested in owning and playing a bass. I purchased a really soft reed so I can blow past the leaks with the original century old pads. It's a synthetic read, and - unless I blow just right - the tip of it articulates the tip of the mouthpiece and yep just as Sergeant Schultz would say: "NO THING !"

[Tim Jackson]

I have not gone down this road of chat lately because it seemed most folks around here were resistant to such ideas. First, I say, it's not about which way you think, it's about what can be gained from the journey of exploration into all ideas.

Here's something I saved years ago:
To Buzz or Not to Buzz | Bob Gillis: M ... ress.com)

In certain ranges of the tuba, to me, it's obvious the lips are not touching.


TJ

[bloke]

Contact is how to dampen a vibration. Percussionists are taught to get their sticks and mallets off of whatever they're hitting as quickly as possible (other than some special effect).

Those who play tuba and use the so-called "one lip trick" for playing extremely low might possibly be using the lip as if it's a drumstick against the inner wall of the mouthpiece, but I'm not certain because I don't employ that technique. When I hear it used, it sounds like suddenly the player is playing a different instrument than before.

[Stryk]

Just blowing air into the horn gives nothing

Did you watch the video? Physicists contend it does.

[bloke]

Just blowing air into the horn gives nothing

I could fashion a single reed mouthpiece, a bassoon reed, an oboe reed, or a jaws harp whereby blowing through any of those mouthpiece or reeds - or plucking that jaw harp - would give me nothing. The embouchure (or mouthpiece/reed/jaw harp geometry PLUS embouchure) promotes the vibration.

Obviously, randomly-tensioned or flaccid lips on a mouthpiece will not promote/encourage/set up a vibration.

flashing on a house:
Only if bent up a certain way (incorrectly, as it's supposed to sit flat down against it's adjacent surfaces) - and with the wind blowing from a particular direction - will flashing on a house vibrate in the wind (as if a single reed, double reed, or pair of human lips).

[tadawson]

Just blowing air into the horn gives nothing

Did you watch the video? Physicists contend it does.

I can just blow into mine, and all I get is basically white noise (the soft sound of air moving) . . . Not sure what "physicist" said that, but apparently not a good one (or was taken out of context)

If the lip is moving at all, for any reason, to me, that's a buzz, not just blowing.

Were this to be true, you could play the tuba with an air compressor . . .

(But no, have not yet watched the video . . . )

[bloke]

With apologies, I can't think of a way to restate what I posted more clearly or more concisely.

When I place my lips into my mouthpiece (inserted into a tuba) and make a fart sound (lips jammed together), there is noise, but it's not any type of noise that believe I could market.

[UncleBeer]

The buzz merely 'tickles' the column of air. Not much air actually goes through the instrument. All you're doing is getting the column of air to vibrate at the resonant frequency which belongs to a tube of this particular length. The vibration travels past the bell (0.6 the radius of the bell), and is bounced back into the instrument, all the way back to the mouthpiece. This wave then bounces again past the end of the bell, back to the mouthpiece, etc, setting up a standing wave, which reinforces this frequency. The degree of how well this standing wave is reinforced by the taper determines the success (or failure) of the instrument's design.

[arpthark]

What about when you hit the bell with a drumstick?

[bloke]

Most everyone agrees that the lip vibration sympathetically vibrates the column of air, but it's difficult to convince some that their lips are vibrating like a reed, rather than like a single-stroke drum roll. I've given up attempting to convince the not-convinced. (What does it matter to me what they believe? I show up where I agree to show up, do it the way I do it, get paid, and go home.)

[Mary Ann]

Reminds me of my very first encounter with a brass instrument. Neighbor found an old WWII pretty smashed up Army bugle in his attic (this is 1950s) and I wheedled my way into owning it. I had been told "it takes a lot of air to play one of those," so I wrapped my lips around the (totally stuck) mouthpiece and blew my brains out. Nothing. I tried everything under the sun for quite a while, and at one point I guess my lips were inside the cup, because for a second I got a sound. But I had NO idea how that had happened, I certainly wasn't buzzing, and I wasn't able to repeat it either.
Finally my dad got home from work, I asked him if he could play it, he made a toot, I said HOW DID YOU DO THAT? and he buzzed his lips.
It went from there --- and I developed the Biceps Method of range on the bugle. Stayed there a very long time, too.
What's sad is that when I did officially take up horn at 45, the instruction wasn't any better.

[UncleBeer]

...the Biceps Method of range on the bugle.

I call that the "Armstrong method". (Arm strong. Get it? It's also a double joke, as it can also refer to a particular overuse pathology known as "Satchmo's Syndrome")