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In Reply to: RE: Whereas a Trombone can generate a Shock Wave posted by John Marks on December 14, 2014 at 08:55:54
Legend has it that Dizzy Gillespie's signature "V-shaped" trumpet was actually the invention of an angry spectator.
As the story goes, Dizzy was blasting away one night when a big guy sitting directly in front of him in the front row got tired of getting blasted and falling over backwards in his own chair. The guy stood up, grabbed Dizzy's trumpet, and bent it over his knee.
Dizzy actually liked the way his *new trumpet* sounded. The rest is history...
Follow Ups:
The scientific literature I have read is all about trombones, and here might be the reason why only trombones:
"Because nonlinear propagation effects are cumulative, the resulting distortion of the signal can be spectacular, leading to the formation of shock waves in the instrument, especially when the tube [read: "slide"] is at its maximum extension (figure 2)."
SOUND MECHANISMS OF BRASS INSTRUMENTS, LAST TWENTY YEARS RESULTS, Joël GILBERT, Laboratoire d'Acoustique de l’Université du Maine (France).
It might seem that the trumpet's tube is too short to have the transient reach speeds faster than the speed of sound.
But as far as the Dizzy G. story goes, a trumpet can get dangerously loud without creating shock waves. Shock waves are different from being just loud.
JM
> The scientific literature I have read is all about trombones:
> "Because nonlinear propagation effects are cumulative, the resulting
> distortion of the signal can be spectacular, leading to the formation of
> shock waves in the instrument, especially when the tube [read: "slide"] is
> at its maximum extension (figure 2)."
The trombone's waveform is also highly asymmetrical; see fig.1 at the page
linked below, which is Art Baron's 'bone captured at the sessions for
Jerome Harris's "Rendezvous" Stereophile CD.
John Atkinson
Editor, Stereophile
Thanks, John...
But, the thing that I have read before in the literature, but which has never been explained, is:
WHY is the trombone's waveform's asymetrical-ness baised toward NEGATIVE?
Tympani thwacks having a negative pressure front makes perfect sense... . Compress the air inside the kettle, rarify the air above the skin.
But trombones don't work like that. I have seen papers about the inside of the mouthpiece, etc., but, frankly, they were observational and never seemed to explain the why of it.
NB, it could be that trumpet mouthpieces work the same, but that the path length inside the trumpet is not long enough to get the mutual reinforcement past the critical point.
Oh well, don't sweat it.
It's not as though we were talking about violins or something really important like that!
John
Pass the Ear Plugs, Please....
A box of them is at each entrance to the Stage at Davies Hall.
Not the Golf-Tee shape, but a dense cylinder of expanding Foam, they work well for Self-Defense.
I tried Custom, but these block more sound.
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