Increase in very low frequency noise perception when one ear is closed

This was observed by chance.


It started off as a test on how accurately two different microphones, each one in turn, would capture outdoor ambient full spectrum noise.


Each microphone was in turn placed near an open window.


Quality was judged by listening to headphones and comparing this to how the ambient noise sounds using our own ears, head close to the window.


At one point the right hand covered the right ear. Therefore only the left ear which was close to the window would hear the ambient noise.


A dramatic increase at very low frequency rumble was perceived. It disappeared when the right ear was uncovered.


This low frequency content seems to be in the region of 10-30Hz.


The experiment was repeatedly performed with the same results. The outcome was the same in various areas including indoors. At some point an earplug was placed on one ear to exclude the possibility of hand induced vibration.


So it appears that when both ears are on there is some cancelation mechanism of this disturbing noise.


Is this another reason why a single microphone when no bass filter is added captures so unnaturally and exagerated very low frequency content?


It seems it captures what is there.


But we humans have a mechanism of canceling this disturbing sound.


A low cut to perception when we use both ears?