HI FYI,
A fluid (explosion) at work:This mpg demonstrates how a compressible fluid reacts as it travels through a structure with partitions:
b
Whether there are reflections from side walls depend in velocity vector of the wave front and it's relation with the wall. How much reflection will create clearly measurable effects depend in the dimensions of the duct compared to the wave length.
A tapered pipe is the inverse of a conical horn, so instead of having a high to low pressure transformation from throat to terminus it has a low to high transformation that increases vent mass loading with increasing taper ratio (where 'vent' = the terminus's elastic boundary condition) same as a simple MLTL mass loads its vent, only much more so.
GM
No paradox, a sound 'bubble' has 'x' amount of particle density, so when compressed as it would be in an acoustically small pipe for the WL it's just an air mass 'slug' slithering back n' forth during compression/rarefaction same as in a vent at resonance.
GM
Precisely stated "it can't", but that is a gross over simplification. If you mapped out the precise locations of pressure contours as the wave wrappped arround it would not be so simple as to be defined as a reflection versus a diffraction - both are going on in various amounts at all time and frequencies.
It's an angle of incidence and (mis)matching impedance situation, so a LF tone won't be so much reflected as flowed out like a liquid and why room gain modes can be visualized as underwater wave motion in a tank.
GM
I guess you did not have a big enough presence to be singled out, but I bet your were close. Better luck next time.
It is unfortunate that he seems to have a lot of anger and frustration with people who will not automatically fall in line with his way of thinking. He definitely does not listen or read references other then his own. I wonder how he will get along with some of the folks at AA, they are not always shy.
I don't doubt that there is a lot going on - reflection, refraction, different frequencies, the whole schlamazel but I like to make it simple - one frequency, say 20hz and one bend, 180*. Let's leave all the other fodder out of it and concentrate on this one situation, ok?
Explain how a 20hz sound wave does a 180* turn without reflecting.
It is for the purpose of describing typical acoustic resonances where the WL is long WRT its container and why MJK's 'simple' 1D wave equation is adequate to accurately sim resonant cavities.
GM
When I have thoughts like this, I find some time spent with the ripple tank applet helps to clarify them. You can see the waves reflecting (or not).
http://www.falstad.com/ripple/
Seriously, MJL? Physics is always about modelling - if a model is formulated, tested against real results, and shown to be acceptably close, the model is useful.
Would you say that you were hearing a lot of rhetoric if, when asked to explain gravity, a physicist told you that it was "pretty complicated, but comes down to mass bending the 3-dimensional structure of space"?
Would you say that you were hearing a lot of rhetoric if, when asked to explain gravity, a physicist told you that it was "pretty complicated, but comes down to mass bending the 3-dimensional structure of space"?
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