Engineering360: "How Soundproofing Acoustic Foam Actually Works"

Part of this is incorrect. The surface being non flat does not disperse the sound. The dimensions are too small to be effective at audio wavelengths. In fact, convoluting or shaping the surface simply reduces the amount of absorption because there is less foam. Published research in support here - https://www.acoustics.asn.au/conference_proceedings/ICA2010/cdrom-ICA2010/papers/p149.pdf

Nice research (and I don't doubt your results for the materials tested), however, it doesn't account for the high aspect ratio wedges one commonly sees in anechoic chambers (https://en.wikipedia.org/wiki/Anechoic_chamber#). In a chamber that has, say for example, 15 degree wedges that are 48" deep, your theory would say that a solid block of the same foam / fiberglass that is 24" deep would produce the same anechoic effect . . . yet no one builds an anechoic room with a flat thickness of absorption material. Any speculation or research references as to at what point the surface irregularity depth / angles do begin to matter for the 20-20KHz range?

The big wedges with acute angles are effective impedance transformers, coupling the impedance of air to the impedance of the absorber. So no different to electrical impedance, it's reasonably easy to calculate. I think you are asking where the cutoff point is when it is more effective than a solid block? Which is worth investigating. But I do think the acoustic anechoic chambers use the minimum possible for sufficient effect as it gets very expensive to build and they would do no more than necessary.

what the convolutions do-- just like rough surfaces with light-- is increase the potential that the pressure wave(s) hit the foam more than once before heading back into "open space"...
Also, the sound is "damped", and the foam is "damping" the sound. "Dampening" has to do with water ;P

rubbish, sound and light is not always a valid analogy. Read the attached published research.

More surface area is only beneficial if it has more absorption behind it. By convoluting the foam you remove absorption.

poppycock, convoluting does not necessitate removal. Convoluting could be performed by addition of material or by distortion of a flat sheet. Either of those cases results in more sound absorbing foam.