Ya my exact thoughts.The whole idea sounded a bit odd to me as well,unfortunately, my first / second year physics is just to old to rationalize a good explanation. I did notice one DIY site for bass traps stressing the importance of having a sealed tube. From this I was infering that the sound waves where compressing the air within the tube causing a loss in amplitude??????????????? As well a Bass trap manufacture showed baffels in their models, meant to elimate standing waves. WIth a standing wave in the tube I guessed this would eliminate compression/expansion of the air in the tube, making it ineffective???????? But I'm just hand waving.........Any physicists out their? Hopefully Alan has some insights on Bass traps and proper placement of absorptive panelling.
Thanks, El