Standing Waves - Loud and Soft spots

[VagrantPirate]

Ok, I've got a conceptual issue that I can't seem to resolve.
Basically, as far as I know, standing waves can be visualised as displacement standing waves or pressure standing waves and I know that pressure nodes are displacement antinodes and vice versa.
However, I've been told that pressure antinodes are "loud spots" due to maximum pressure variation although I've also heard that displacement antinodes are "loud spots" due to maximum displacement of the particles. Obviously, they can't both be loud spots so which one is true and what's the theory behind it? It would be appreciated if the loud/soft spots could be explained in terms of both pressure and displacement.

 

[sophiecentaur]

I think the answer to this one involves what you mean by "loud". Afaik, your ears respond to pressure so the subjectively loud spots will be where the pressure variations are greatest. For a nice long wavelength of sound - say 100Hz / 3.3m - you wouldn't 'hear' the air rushing back and forth round your head (at pressure nodes) as much as you would 'hear' the large pressure variations a quarter wavelength away. BUT, because your head would get in the way, the waves won't behave quite the same as they would if they were unimpeded. There will be resultant pressure changes around your ears even at the velocity antinodes.
'Proper' measurements would involve small (enough) velocity or pressure measuring probes - then you would get good nodes and antinodes.