Why is it that sound from a sub-woofer is non-directional?

Question

You know how you can't tell which direction sub-woofer sound is coming from (and that's why, in large part, it doesn't matter where in the room you put your sub-woofer).

Is that because sub-woofers make everything in the room - possibly including your head - vibrate and the sound seems to be coming from everywhere?

Is it because the wavelength of sound in that frequency range exceeds the size of the room?

Is it all of the above or is it another reason altogether?

Thank you!

Answer 1

its because no noise come from the actual woofer.. it comes from teh air getting moved around in the box.. and the box doesnt project the noise it just "thumps"  

Answer 2

Grumpy Mac has the right idea. Due to the combination of wavelength and wall reflections it is very difficult for humans to localize low frequencies in a small room. By small I mean anything short of a concert hall.

If your sub-woofer is set at the proper volume most people can not tell what direction sounds from 80Hz and lower are coming from. It has nothing to do with the extremely small difference in the time the sound hits one ear as opposed to the other ear since after even one reflection the timing cues are muddied and bass frequencies can reflect multiple times in a normal room.

Answer 3

The lower a frequency, the less directional it will.  For the most part your subwoofer creates "inaudible" tones which are felt rather than heard.  If you are really hearing your subwoofer, this means that the crossover is set too high and that is creating a localizing effect(you can tell where it came from).

Why do you think whenever the voice of God(which is usually very deep and weighty) is portrayed in a movie, it sounds like it is coming from everywhere?

Also the waves on very low tones are so long that the space between your ears becomes inconsequential compared to the wave length.

Answer 4

Subwoofer sound IS directional. In a parking lot you can tell the direction of a 'boom car'.

But you get a LOT of subwoofer sound by wall reflections in a room rather than by direct radiation like other speakers.This is why people say it is omni-directional.

The frequencies from a sub often exactly match the length of a wall in the room. I cannot remember the formula, but the walls in a room will reflect some frequencies better than others because the wall-length matches 1 frequency, 2X the frequency and even 4 X the frequency.