Regarding Low Frequency...In any large hall used for recording there is a very low frequency rumble that is always present even when the musicians have gone out to lunch. It represents the natural frequency of the hall, and is excited by such things as the air conditioning system and passing road trafic. This subsonic noise is plainly audible on some recordings if you have suitable speakers and you don't activate your rumble filter.
But is it "noise"... something undesirable. It can be argued that this "hall sound" is part of the musical experience, and reproducing it adds to the realism of the recording. I find that is true for some recordings and not for others, probably depending on how severe the background rumble is.
But is it "noise"... something undesirable. It can be argued that this "hall sound" is part of the musical experience, and reproducing it adds to the realism of the recording. I find that is true for some recordings and not for others, probably depending on how severe the background rumble is.