I suppose it depends on the temperature differences room vs operating temps.
but here, my older samsung plasma used to "creak" after being turned off (as it cools down)
I think the former poster is confusing the LCDs with PLASMA monitors
PLASMA are the ones that get VERY HOT and buzz and creak ( plastic and metal expansion due of heat)
Aah I see, I honestly think those buzzing is most due of bad quality components or electrical noise in the power lines (usually when the houses have bad cabling or constant spikes)