Acoustic filter

[johnab]

(a)what makes side branch to act as high pass filter, expanson chamber as low pass, helmoltz resonator as band pass?
(b) how to define location of side branch/helmoltz on duct?

tried to look into internet like wipikedia/SAE paper but didn't able to find answer so proper direction would be appreciated.

 

[johnab]

I think my previous question probably misunderstood or really not sure. The question was what mechanism or physical process to act:

(a) quarter wave as high pass filter that attenuate low
frequency (I understand, defintely the phase change
activitiy at open end)

(b) expanson chamber as low pass filter to attenuate high
frequency (there would be reflective wave when it
expands)

(c) Helmoltz to act as band pass or low pass & how to
control that?

I apppreciate if some one can reply,

 

[GregLocock]

http://asa.aip.org/publications.html#pub04

Cheers

Greg Locock

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