Re: What makes the sound?
Posted: Thu Oct 31, 2024 10:09 am
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It is because the frequency at which they vibrate is caused by the length of the column of air and the amount of air pressure sent past the lips.
Meanwhile we're smh about 1) that "bang against each other" story that thoroughly misrepresents what happens, and 2) the denial of photographic evidence.
Sure, and they show what happens when those people played, when the photos were taken. This is tautological. I don't think it proves that all players on every brass instrument always look the same - especially when the article says they don't. Without photos of a tuba player, moderate volume, middle range note like lower half of the bass clef ... I can't guarantee that lips would close in that case. They likely do, sure, but there's no inherent reason they must.
It's tedious to be interrogated by someone who doesn't seem to have read what I wrote. I have been at some pains to repeatedly point out that, as i understand it, whether the lips touch does not matter to the production of sound. I have several times on preceding pages of this thread presented quotes wherein the physics story is that the lips apparently do not touch in some playing situations. When is that? They say, with high notes, and they say why. You can go back and read it if that's interesting to you.bloke wrote: ↑Thu Oct 31, 2024 1:47 pm - As you (finally) admit that you "can't guarantee that lips would close in that case" (as I contend that closing them would stop the vibration), why would they necessarily close at higher frequencies - such as a tuba player "squealing" out pitches way up at the top of the treble clef staff and above?
It is the standing wave that does the lips vibrate.bloke wrote: ↑Thu Oct 31, 2024 11:49 am non sequitur
Once the engineer understands the mechanics, they're stop.
If they never understand them, they'll never stop.
The air column and the air pressure (via air restriction - a venturi) cause the lips to (individually) vibrate.
Jamming the lips together and making a fart sound into an input receptacle does not cause the air column to vibrate.
The standing wave makes the air pressure in the mouthpiece positive and negative.
It isn't that because of some exceptions which will probably exist that you can dismiss the positive and negative pressure in the mouthpiece forcing the lips in and out and the fact that the efficiency of the standing wave being reflected is the highest when it hits a solid object and not one with a hole in it, that you can state no inherent reason with a high probability factor.donn wrote: ↑Thu Oct 31, 2024 12:47 pm
Sure, and they show what happens when those people played, when the photos were taken. This is tautological. I don't think it proves that all players on every brass instrument always look the same - especially when the article says they don't. Without photos of a tuba player, moderate volume, middle range note like lower half of the bass clef ... I can't guarantee that lips would close in that case. They likely do, sure, but there's no inherent reason they must.
Yes, it isn't like your lips produce frequencies the way a guitar string does, out of their own resonant properties. The air column is the resonating element, here. Lips play a role, but not that role, so it luckily doesn't matter that a lip really doesn't have any resonant property at all.
If I understand you ... I'm just going from the resource you posted, where 1) they believe that under some playing regimes the mouth doesn't actually close, and 2) they explicitly saypeterbas wrote: ↑Thu Oct 31, 2024 3:05 pm It isn't that because of some exceptions which will probably exist that you can dismiss the positive and negative pressure in the mouthpiece forcing the lips in and out and the fact that the efficiency of the standing wave being reflected is the highest when it hits a solid object and not one with a hole in it, that you can state no inherent reason with a high probability factor.
I.e., a hole is enough like a solid object, if the hole is relatively small. If you think that's too sloppy, maybe you'd like to present a discussion of the acoustical closed pipe in terms of a regime where the solid object appears at only one point in the cycle, and during other parts of the cycle there's a hole. I don't know enough about it myself, to say whether that's sound - if the reflection effect happens to apply only at that bottom pressure.For a sound wave, the tiny aperture between the lips – which is on average a much smaller cross section than the bore of the instrument – is enough to cause a reflection approximately like that from a completely closed end.
The camera is an IDT high speed camera with a Nikon Nikkor 35 mm lens. The movie probably has been compressed a lot to be on the website but you can always reach out to the author if he wants to send you a better copy.bloke wrote: ↑Thu Oct 31, 2024 1:47 pm This picture is even crappier than that lips movie...
crappy pic.png
...but
- The movie is low resolution.
- It's not known where the mouthpiece was drilled to insert the tiny camera. The ideal angle would be just below center (as most trumpet players play "down-stream", but that spot would interfere with the throat).
- The higher the pitch, the tinier the space between the lips (just as with the epic difference between oboe double reed and bassoon double reed openings). With trumpet playing, the arc becomes - again - just about microscopic, and the blurry movie is anything-but at the microscopic level, and nor (from what I've seen) is it pointed straight on at the nearly-microscopic space between the lips...so there's really nothing to be seen that demonstrates anything for certain.
- As you (finally) admit that you "can't guarantee that lips would close in that case" (as I contend that closing them would stop the vibration), why would they necessarily close at higher frequencies - such as a tuba player "squealing" out pitches way up at the top of the treble clef staff and above?
Why would a higher frequency range necessarily create an allowance or an exception?
summary:
- crappy low-res micro-camera movie
- unknown filming angle (which could well not reveal the opening, due to where the hole is trilled and how the mouthpiece is "clocked")
- admission that lips could possibly vibrate without touching each other
- as lips (and oboe reed blades vs. bassoon reed blades) become infinitely closer to each other (as the frequency increases) they can certainly become closer-and-closer to each other, YET never actually touch (at the tinier-and-tinier spot where they continue to vibrate at higher and higher frequencies).
One of you just loves charts and graphs. Here's a graph showing an arc whereby the arc creeps infinitely closer to nothing, YET never reaches nothing:
(something I was shown in elementary school)
Seriously, you two guys are pm-ing each other and coordinating your trolls, yes?
Also:
I've heard that people who deal in "engineering" and "science" stuff - who encounter others who disagree with their observations - often embrace a hobby of (regardless of what actually is - which isn't the point) attempting to demonstrate that those - who disagree with their findings - are foolish or stupid...(again: a whole bunch like the totalitarian/equal distribution/keynesian -vs- libertarian/free-market/hayekian arguments on social media). I'll READILY ADMIT that I am both foolish AND stupid, if that's what y'all are attempting to pull off.
You are of course right that we have very little measurement of different players and different instruments but that is because setting up a scientific sound experiment is expensive.donn wrote: ↑Thu Oct 31, 2024 3:21 pmIf I understand you ... I'm just going from the resource you posted, where 1) they believe that under some playing regimes the mouth doesn't actually close, and 2) they explicitly saypeterbas wrote: ↑Thu Oct 31, 2024 3:05 pm It isn't that because of some exceptions which will probably exist that you can dismiss the positive and negative pressure in the mouthpiece forcing the lips in and out and the fact that the efficiency of the standing wave being reflected is the highest when it hits a solid object and not one with a hole in it, that you can state no inherent reason with a high probability factor.I.e., a hole is enough like a solid object, if the hole is relatively small. If you think that's too sloppy, maybe you'd like to present a discussion of the acoustical closed pipe in terms of a regime where the solid object appears at only one point in the cycle, and during other parts of the cycle there's a hole. I don't know enough about it myself, to say whether that's sound - if the reflection effect happens to apply only at that bottom pressure.For a sound wave, the tiny aperture between the lips – which is on average a much smaller cross section than the bore of the instrument – is enough to cause a reflection approximately like that from a completely closed end.
[edit] You may obtain extra credit for a discussion of the same principle in the saxophone or clarinet, where I believe we agree that the reed doesn't always close. [/edit]
I haven't read much about saxophones, but there is someone at a uni in Belgium doing a Phd on this and one of his preliminary experiments shows that the reed closes 20% and even more depending on the mouthpiece which is a lot longer then lips on a mouthpiece.donn wrote: ↑Thu Oct 31, 2024 3:21 pmIf I understand you ... I'm just going from the resource you posted, where 1) they believe that under some playing regimes the mouth doesn't actually close, and 2) they explicitly saypeterbas wrote: ↑Thu Oct 31, 2024 3:05 pm It isn't that because of some exceptions which will probably exist that you can dismiss the positive and negative pressure in the mouthpiece forcing the lips in and out and the fact that the efficiency of the standing wave being reflected is the highest when it hits a solid object and not one with a hole in it, that you can state no inherent reason with a high probability factor.I.e., a hole is enough like a solid object, if the hole is relatively small. If you think that's too sloppy, maybe you'd like to present a discussion of the acoustical closed pipe in terms of a regime where the solid object appears at only one point in the cycle, and during other parts of the cycle there's a hole. I don't know enough about it myself, to say whether that's sound - if the reflection effect happens to apply only at that bottom pressure.For a sound wave, the tiny aperture between the lips – which is on average a much smaller cross section than the bore of the instrument – is enough to cause a reflection approximately like that from a completely closed end.
[edit] You may obtain extra credit for a discussion of the same principle in the saxophone or clarinet, where I believe we agree that the reed doesn't always close. [/edit]