Can bass traps be free standing?

... sound waves CANNOT bounce off empty space...

Mmm...I don't think anyone suggested that.
It's really about the "corner"...the walls/floor all connecting to form the corner, trap the sound waves there.

The point was that having the corner door open, doesn't let the LF "escape". It may help some...but the buildup is still there, and you need to find a way to put some trapping there, even if it something movable, just to suck up the LFs.

I wonder if it makes more sense to close the door, and also put some trapping there...that way there is a symmetry between the two corners...rather than leaving the door open at one corner....?
 
It was my understanding that sound absorbance was referenced to an open area, a "hole" if you will that opens onto infinity.
Thus any form of material in the way must have an absorbance less than the hole?

Dave.
 
It was my understanding that sound absorbance was referenced to an open area, a "hole" if you will that opens onto infinity.
Thus any form of material in the way must have an absorbance less than the hole?

Dave.

You lost me there buddy...

From what I understand: High frequencies are more easily reflected. Low frequencies travel through structure while also reflected and build up in corners. That is obvious just by sticking ones head in the corner of any room. Worse at intersections between two walls and ceiling/floor.

The tough part is controlling room modes that low end frequencies travel. Especially in small rooms.

There is no way to actually absorb all low end frequencies. But treatment does help.

Not sure about the whole 'hole' size thing you mentioned. Either way, acoustic treatment is advised. Hole/door/closet, whatever. It better addressing the situation than ignoring it.
 
Mmm...I wouldn't call an "open hole to infinity" as absorptive.

Absorption of sound is more about the friction and conversion to, and dissipation of heat energy.
There is friction in air...but most other materials will create more friction...so an open hole would not be more absorptive, it would let the sound pass more easily and away...but the "infinity" thing will rarely apply in any real-life situation WRT to audio recording.

Back to the door/corner thing...sound waves often are depicted in a linear, "singular" way...but they're actually radiating in a 3D circular way, and so even if your speaker is aiming at the open door in a corner, you'll never be able to "aim" all the sound to pass through the door.
I know this is obvious to most of us...I'm just saying it to better make the point about why the open door in a corner doesn't solve LF buildup. :)
 
Mmm...I wouldn't call an "open hole to infinity" as absorptive.

Absorption of sound is more about the friction and conversion to, and dissipation of heat energy.
There is friction in air...but most other materials will create more friction...so an open hole would not be more absorptive, it would let the sound pass more easily and away...but the "infinity" thing will rarely apply in any real-life situation WRT to audio recording.

Back to the door/corner thing...sound waves often are depicted in a linear, "singular" way...but they're actually radiating in a 3D circular way, and so even if your speaker is aiming at the open door in a corner, you'll never be able to "aim" all the sound to pass through the door.
I know this is obvious to most of us...I'm just saying it to better make the point about why the open door in a corner doesn't solve LF buildup. :)

No, I am not saying that an opening will fix LF standing waves, it is clearly impossible to use "nothing" in a room to control sound. I just mean that, as someone else said, "sound goes out, never to return" ("infinity" is used in the practical sense that any reflecting surface is too far away to matter)
No kind of sound absorber is as "perfect" in fact it was said that the mechanism is the conversion to heat by internal friction. Thus, there must be particle movement to create friction and if there is movement there must still be sound energy left. Unless the absorber was "infinitely" thick?

"aiming" at the hole? Sound in a room is a diffuse field. (with "hotspots")

Err? Some of you might be pleased to know I shan't be around for a few days, maybe a week. Major op.

Dave.
 
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