Room Acoustics to reduce Echo.

I would like to a avoid rockwool and glasswool because of the harmful properties vis a vis the chemicals... Which is why I was thinking of using thick foam or even cotton filled mattresses with a cotton cover.. But as you said it does not absorb the lower frequencies, I will take look for other alternatives..
 
I was also in a similar boat so decided to build a box with the thinnest plywood and then fill the box with rockwool and then seal it. In this way, the rockwool cannot harm you plus the thin plywood doesn't do anything for mid to low frequencies.
 
I was also in a similar boat so decided to build a box with the thinnest plywood and then fill the box with rockwool and then seal it. In this way, the rockwool cannot harm you plus the thin plywood doesn't do anything for mid to low frequencies.
This seems like a nice alternative. Is it built or yet to be done? If its built, do you have any pic of your box and how and where you have placed? Its dimensions. How much of Rockwool you have placed inside the box. Is it high density or low density type..
Sorry for the long list of questions. :p
 
Here is the post from a thread where I had detailed on how to build it.


Obviously one can build bigger and deeper ones. While ideally one would need to use loose rockwool but that thing is super messy and itchy to handle to I went back to 48 density slabs. If I had to rebuild it would have alternated the slabs with air gap and made a thicker bass trap possibly a feet in depth atleast.
 
Sorry OP for few off-topic discussion..

I would like to a avoid rockwool and glasswool because of the harmful properties vis a vis the chemicals... Which is why I was thinking of using thick foam or even cotton filled mattresses with a cotton cover.. But as you said it does not absorb the lower frequencies, I will take look for other alternatives..

Am not sure if Ceramic wool will be of the same category as Rockwool / Fiberglass.. But i had seen my brother using it for the DIY car exhaust experiments.. I had read abt ceramic wool sound absorption properties. but can't seem to find the chart.. But vaguely remember, it has lesser absorption in low freq.. But if one increases the size, there there is some absorption..

Here is one article, if you wish to consider it - http://www.ceramic-fiber-blanket.co...r blanket has,density and air flow resistance.
 
If it helps

Table 5.1 Typical porosity values for some
materials from References 5 and 1
Material Typical porosities
Mineral wool 0.92–0.99
Open cell acoustic foams 0.95–0.995
Felts 0.83–0.95
Wood fibre board 0.65–0.80
Wood wool board 0.50–0.65
Porous render 0.60–0.65
Pumice concrete 0.25–0.50
Gravel and stone chip fill 0.25–0.45
Ceramic filters 0.33–0.42
Brick 0.25–0.30
Sinter metal 0.10–0.25
Firebrick 0.15–0.35
Sandstone 0.02–0.06
Marble 0.005

Source: Acoustic Absorbers and Diffusers: Theory, Design and Application - Trevor Cox, D'Antonio
 
If it helps

Table 5.1 Typical porosity values for some
materials from References 5 and 1
Material Typical porosities
Mineral wool 0.92–0.99
Open cell acoustic foams 0.95–0.995
Felts 0.83–0.95
Wood fibre board 0.65–0.80
Wood wool board 0.50–0.65
Porous render 0.60–0.65
Pumice concrete 0.25–0.50
Gravel and stone chip fill 0.25–0.45
Ceramic filters 0.33–0.42
Brick 0.25–0.30
Sinter metal 0.10–0.25
Firebrick 0.15–0.35
Sandstone 0.02–0.06
Marble 0.005

Source: Acoustic Absorbers and Diffusers: Theory, Design and Application - Trevor Cox, D'Antonio

Absorption rate at specific freq is more critical and would also be helpful.. Plz share if you have link to that table or in PDF..
 
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