material with highest absorption coefficient at low frequencies

[Tenson]

It is used for filling cavity walls.

 

[rl guy]

ouch, i couldnt wait and already purchased and paid for that stuff on ebay.

building supply store like lowe's and home depot?

 

[Cal Weldon]

That other stuff is a water retainer for in plant pots. Hope you like gardening. As mentioned before: Go to the lumber yard and get some rock wool batts. You may have to buy a bag but that will be extra for future projects and can always be stored in your attic when not in use.

 

[Inductor]

rockwool(sheet)

 

[thadman]

very well said Svante!
thadman, fiberglass and rock-wool has almost the same absorptive data if same compression (so same weight). Any store of products for heat insulation has large range of products...the more density, the more absorption in the bass range.
Follow what said Svante, he is right; if you don't have enough room to place rock-wool panels at least 1m far away from walls you will not get any low-bass absorption.

Does Rock wool have the same acoustic properties as Corning Owens Rigid Fiberglass for a given density?

Also, I heard it mentioned that higher density lends itself to reflecting higher frequencies whereas lower density absorbs less. Why not cover the front with low density fibers and then progressively transition to denser fibers?

Should I even bother myself with reflections (ie density argument) off the fibers at the frequencies im concerned with (10-100hz) or just go with the densest fibers I can find?

 

[Ron E]

I'm just trying to get an idea of how many feet of said material I'd need to have a 1.0 absorption coefficient at 10hz.

I think you need to back up and start at the beginning. Describe the problem.

 

[MJL21193]

Does Rock wool have the same acoustic properties as Corning Owens Rigid Fiberglass for a given density?

Rockwool is denser to start with, it has better sound dissipating properties than fiberglass.

Also, I heard it mentioned that higher density lends itself to reflecting higher frequencies whereas lower density absorbs less. Why not cover the front with low density fibers and then progressively transition to denser fibers? [/B]

In order to dissipate sound waves in the low bass range, you have to take the wavelength in consideration. The material has to be thick enough to react with as much of the wave as possible. This thickness can be reduced by having the wave bounce back through it, or back and forth - such as a bass trap.
The average listening room with window drapes and furniture and carpet may have enough treatment for high frequency.
Better to concentrate on midrange to low.

 

[Inductor]

I think you need to back up and start at the beginning. Describe the problem.

Lead also has very good acoustic properties.
Are you building a sub? or just being scientific about it. If a studio (or public-interior use) you need to be careful with fire (fireproof materials). Please give some more details where you want to go.

 

[banana]

Nothing beats resonator on bass absorption.

 

[banana]

Either tuned port or passive radiator works well below 100Hz.
It needs tunning to get right though.