Originally Posted by ChaoticG8R
That tone is not actually audible. Any perception of sound is due to mechanical/air movement.
It's possible, however what we're hearing in that video is just as you state, the mechanical actions of items moving in the room, and air movement via the ports perhaps.
To utilize tones this low, you've got to determine the actual distortion level of the sine wave generator to begin with. Many so called tone generators are heavily fraught with high levels of distortion.
Also, and most importantly here, is the threshold of human hearing at these low frequencies. Our hearing and detection of these very low frequencies is anything but linear. It varies according to level, and with frequency. The threshold at 10hz is approximately 98-100dB. Conversely, the threshold at 20hz, one octave higher, is about 70db.
That said a pure, undistorted tone, at of 10hz and 100 db is barely audible. However, 100dB at 20hz is 30dB above audibility. Playing loud, low frequency tones indoor, creates all types of noisy artifacts in structural movement, driver noise, port noise, items within the room vibrating etc. I prefer to purchase small sticky back felt pads, and with tone generators at various frequencies, go around the room and seek out noise producing items,...and silence them. There is even a hand held, hard wired remote called "The Rattler", just for such use.
Additionally, even if you fed the drivers a pure 10hz tone, and you were in a concrete bunker with no moving parts and pieces for room noise, the sound emanating from a sub system is likely to be a significant amount of upper harmonic distortion.
All said, still the room shaking, and all the accompanying sounds are still very exciting, and add a wonderful visceral component to the HT experience.
Thanks for sharing