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Ed Anderson wrote:
According to the theory (If I understand it correctly) what is happening to deaden the sound is that the exhaust pulse encounters a disc (what appears to it as a solid disc) and is reflected backwards. When it encounters other incoming waves it interacts destructively thereby attenuating both waves. If energy survives to reach the up-stream end of the chamber it hits that disc and reverses direction again, etc. This would occur in each of the chambers between discs repeatedly many times a second. So you have this chaotic mixing of the waves in the chambers attenuating the sound wave but not seriously interfering with the exhaust gas movement out the tube (hopefully).
The sound waves are reflected from each side of each disc and a bit from the open end as well - however, if the discs have done their job the exhaust sound pulses are considerably attenuated by the time they reach the end of the tube.
Ed
Another very lucid explanation. Thank you, Ed.
My thought is, could you reflect multiple waves over the same distance by having a disk with a large hole for the short waves, then a disk with a smaller hole for the longer wave? Let's see if I can do as good a job of ascii art as Kevin:
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A
-B--|
|--C--|-D--|
|----E-----|
|F-|
So, you have wavelengths A through F, all attenuated within the same foot or so of tube.
--
http://www.ernest.isa-geek.org/
"This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."
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