Originally Posted by G. E.
I've never "noticed" this impedance jump principle in the literature before. I guess I'm back on track with the well-known corner bass-traps.
GE, regarding the tangent, the entire concept of absorption and diffusion is based upon the concept of complex impedance, just as it is more commonly encountered in electronics.
Each material has a characteristic acoustical-mechanical impedance. And each transition involves the acoustical analog of the maximum transfer theorem.
And using the acoustical analogy of the the maximum transfer function, a perfect impedance match between signals transported via mediums of different complex acoustical impedance results in all of he acoustical energy being absorbed.
Likewise, any differences in the impedance match between signals results in a dependent mix of partial absorption and partial reflection with respect to both time and frequency, the degree and nature of each being dependent upon the degree and manner of mismatch.
This perspective provides a much more comprehensive view of such behavior. But it one wants to delve into it in significant detail, one must be open to dealing with the language defining the precise relationships - math.
A pretty good and accessible description of the concept is presented in chapter one of
D'Antonio & Cox.