I just realized that there are quite a few replies from Dave. Definitely put a twist on things and opened a can of worms. I need to check out more info. Thank you.
A pipe is onlya half-wave resonator if it is sealed (or open at both ends). A voigt is a quarter-wave resonator. Note that they all really need mass-loading mto help tame th eripple. And that also gives you more latitude/degrees of freedome in the actual line geometry.
