Eminent Technology are a company who speacialise in sub woofers capable of reproducing sound down to 1Hz. Thats right just 1Hz!! The speaker requires installation into a purpose built attic or basement space which works as an infinite baffle/resonant chamber so you don’t actually get to see the cone of the speaker oscillating at 1Hz, but you’ll feel it. And their sub driver looks like no other, its rotary:

According to their website: “Subwoofer electronics usually contain a cutoff filter which sharply rolls off content to the subwoofer below 20Hz to protect the speaker. On the other hand, the rotary woofer has enough acoustic output to move an open door back and forth .5” between 1 and 5Hz! It has enough output to find resonance frequencies of walls and ceilings in a room….”
And based on the warning that comes with the downloadable demo dvd (here) the sounds it can reproduce might well cause a “normal” subwoofer to self destruct…

The warning includes, one presumes, messes created by playing the legendary brown note

So just how low can a sound be & still be perceived by human ears/body organs? According to Eminent Technology that depends on the power feeding the subwoofer, as their research indicates below, extending the Fletcher Munson curves (ie equal loudness contours for the human ear) to much lower frequencies.

There is also a very interesting description of a series of listening tests the company held with a group of 11 ‘audiophiles’ – have a read here as the results are interesting: “There was no difficulty in distinguishing between the tracks that included 4, 8 or 16Hz. The order of file playback did not appear to have any affect on the outcome. Because of room wall/door vibration this test might have validity to 8Hz, certainly to the frequencies above that. The room could not take a clean 4Hz sine wave at 104dB so the perception at this frequency was likely the result of room motion.”

‘Room motion’ – ayekarumba!
Just prey your neighbours don’t get one for their home theatre!!