AtD: The Parsons-Short Auxetophon

[Robin Landseadel]

Naturally, the link concerning the Parsons-Short Auxetophone had to,  
in some way, connect to "The Rocket":

	AUXETOPHONE TECHNOLOGY TODAY.
	Surprisingly, it's important. Very important, in its specialised
	field. We probably wouldn't have got to the moon without it.
	Compressed air modulated by valves is used to generate
	enormous sound levels in test chambers.

	Left: Compressed-air noise generator.
	The machine in the picture can generate a Sound Pressure
	Level of 165 dB from an air supply at 120 psi. The air is
	modulated by a servo-driven reciprocating poppet valve that
	sounds as though it is the direct descendant of Parson's comb-
	valve.

	To put this in perspective, 130 dB SPL causes instant hearing
	damage. About the only thing in the world that generates such
	extreme levels as 165 dB is a rocket engine at close quarters-
	and that is exactly what these noise generators are used for-
	testing rockets and jet aircraft to make sure they can withstand
	the noise of their own engines.

	Sometimes it is Rocket Science.

http://tinyurl.com/yk2uje4