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We all know that breathing helium makes our voices squeaky, because the speed of sound in helium is about 3x that of air. Slightly less well-known is that breathing sulphur hexafluoride gas has the opposite effect, making our voices bassier; this happens because the speed of sound is about half that
So, take a valveless trumpet, and add two valves. Normally, the valves on a trumpet change the length of the resonant column of air, which allows the player to produce a wider range of tones than he otherwise could. These valves work a bit differently.
Two tanks of pressurised gas, one containing He and the other containing SF6, are connected via the two valves to a small nozzle mounted next to the mouthpiece of the trumpet. The player operates the valves while inhaling, allowing fine control over the exact He / SF6 / air mixture in his lungs. The variable gas composition, and hence speed of sound within the instrument, provides the player with an even greater range of tones.
Since SF6 is heavier than air, it is recommended that players stand on their heads periodically during long performances, to allow it to drain from the lungs.
Or use flammable gas... [csea, Mar 02 2011]
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||Would it not work if the gas were injected into the vibrating air column in real time as the trumpeter played? No ingestion should be needed.
||I'm not sure. I did wonder about injecting the gas immediately downstream of the mouthpiece, but I don't know enough about the physics of these instruments to be able to say how much you could inject before it would disturb the resonance.
||Certainly it would reduce the range a bit, though, since inhaling the gas allows you to play a 100% He or SF6 note; something which is impossible if the player is always exhaling 100% air.
||Besides, the risk of filling your lungs with SF6 and passing out just seemed so much more half-baked!
||Hmm. You've got me thinking about building a gas-tuned pipe organ, now. I won't post it as a separate idea though.
||Couldn't extended-range-trumpeters get a peircing in their cheek which can be connected to the tanks of gas with valves oparated by foot pedals - length of playable note now only limited by lip stamina and tank capacity. The plug for the peircing could have a valve in it to allow oral pressurisation in the event of trumpeting without tanks connected.