Physics question

[Acemorgan]

I broached this subject on another forum about a year ago, and didn't receive much useful feedback. Feedback yes, useful no.

Having switched to euphonium from contrabass tuba, my upward expansion has been slow, but is progressing. But I have hit a significant sandbar as I try to go from F4 to the G or even the Gb above it. And I have begun to wonder about the physics involved.

Specifically: you can play C4 with either 1, or 1-3, or with the compensating 4th. So, if the first valve lowers pitch by a major second, when I play that C with the first valve, am I actually using the vibration speed needed for the D just above it? Or when I use 1-3, am I lowering what would otherwise be an Eb to produce the C? Or since the compensating valve lowers the tone by a 4th, am I using the vibration needed for the F4, but sounding the 4th below it?

My point in all this is: the open F4 is pretty consistent for me, but the next open note, Bb4, is a real challenge. Is the G4 "sandbar" a result of having to actually "play" that Bb4, with the addition of a couple of valves pressed? So moving from F4 to G4 is more like going from the F to the Bb?

I realize, bottom line, it takes patience and practice to attain range, but does my theory have merit? This has been bugging me for a while.

Maybe this is why some teachers have emphasized playing through the harmonic series to build range?

Sorry for being long-winded, but I was hoping to make my point clear.

[bbocaner]

no, your lips are vibrating at the same pitch as the note is, period. Doesn't matter what partial you are on or how much tubing you are going through. what can change is the width of the slot and how much resonance you get from the instrument to "lock in" the note on a specific partial. Depends on the acoustic design of the instrument, typically the most secure slot is the one that requires the least amount of tubing, but that isn't always the case.

[franz]

To obtain the upper register, in addition to the practice, it is necessary that the air is blown through the lips at high speed: the higher you go in register, the higher the air speed. The position of the tongue also has its importance: in the low register it should be positioned as if to pronunce the syllable ah, in the middle eh, in the high i, and in the hyper acute sh.

[RickF]

Not sure this is the physics you’re looking for but Sara Willis (hornist) has a video of her during an MRI while playing a natural horn. Linked below is what happens to her oral cavity when slurring to higher notes.

http://www.youtube.com/watch?v=MWcOwgWsPHA&t=1m45s

[dsurkin]

no, your lips are vibrating at the same pitch as the note is, period. Doesn't matter what partial you are on or how much tubing you are going through. what can change is the width of the slot and how much resonance you get from the instrument to "lock in" the note on a specific partial. Depends on the acoustic design of the instrument, typically the most secure slot is the one that requires the least amount of tubing, but that isn't always the case.

Barry is correct. Think of the 9 feet of brass as a megaphone - it takes your lip vibrations and amplifies them (also changes the tone to something beautiful). When your lip vibrations occur at a speed that coincides with the overtone series of a particular fingering (i.e., a particular length of the tube), then the note comes out clean. You can hear an example of when this goes wrong - imagine playing a fast passage and your lips, guided by your ear, aim for a particular note, but your fingers get it wrong. You'll hear a bad note - one lacking tone, resonance, etc. (or as my granddaughter once described a bad note, "sounds like a fart").

Those who know more physics than I do can probably correct any mistakes in my description.

[hyperbolica]

I agree.