brian mitchell wrote:

Density and Decoupling are the two main requirements for sound
absorption, so the best materials are loose and heavy: sand and earth.

For a recording studio I would build a wooden frame of, say, 2" x 2"
battens as far inside the brick wall as you can bear to lose space, but
a minimum of 3" I'd think, and fill the gap with loose dry sand in
plastic bags, pedal-bin liners for example. I would fix something like
weldmesh to the inner edges of the frame uprights (ie., between the
frame and the brick) as I went up with the sandbags to keep them in
place. The sand would entirely fill the gap between brick wall and frame
but it wouldn't create an acoustic bridge and would be highly absorbent
in both directions.

Thanks, that sounds both suitably cheap and within my DIY capabilities.

The same sort of thing would work for the ceiling or roof.

That doesn't though, but:

Another idea would be to have a turf roof and not worry about
the weather.

Two birds with one stone; I've always wanted a turf roof.

I don't know if the floor would need treatment of any kind. A concrete
slab on earth is pretty deadening, I would have thought. But if train or
traffic rumble, for instance, was getting picked up then a floating
floor of carpeted chipboard flooring just sitting on sand would reduce
it well.

I'm more concerned with making the floor warmer.

Daniele
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