# how to achieve a reduction of noise of -60 dB in as little thickness as possible of insulation material?

I am looking into materials to acoustically insulate a room, and I need to do it in as little thickness of the material as possible.

I found something called Balterio which is a 3 mm thick stuff sold in a roll, looks a bit like aluminum foil. It claims to reduce sound by 22 dB. Which compared to other materials and their thickness required to achieve such a sound reduction, seems a bit unbelievable. Does it really work?

Can I put three layers of this, and achieve 66 dB reduction, which would mean that people speaking on one side of the insulation would be completely inaudible on the other side: normal speech is about 60 dB, minus 66 dB would be below 0 dB - the threshold of hearing - and all that under 1 cm thick? If this stuff was so good, then everyone would be using it in audio recording studios instead of making massive thick complicated walls to reduce by that 60 dB? Where is the catch?

If it doesn't work that way, that what can work, to reduce by 60 dB (for example from 80 dB loud traffic noise to 20 dB at which you can sleep comfortably), in the least possible thickness (certainly not more then 5 cm), at an affordable price?

Think about what you are hoping for. A 10dB reduction means reducing the sound power by a factor of 10. Dropping the sound power by 60dB therefore means reducing it by a factor of 1 million, or stopping 99.9999%

To put this in context, this is equivalent to building a wall that blocks 100% of the sound, (let's say the wall is 9' tall by 10' wide), and then leaving a 1/8" diameter hole in it.

See also the wikipedia article on sound transmission class, which suggests that typical interior wall construction gives STC 33, and that STC 45 is sufficient for loud speech to be inaudible. STC 45 can be achieved with double layer of 1/2" drywall on each side of the partition, over wood studs with batt insulation in the wall.

The material also works by being an impedance mismatch to the floor below and the flooring material on top. It limits the amount of sound from the concrete into the material and the from the material into your floor

Simply doubling the material wouldn't help - you would have to have three layers of concrete-insulator-flooring.

There is a material for walls made of neoprene (wet suit material) which you put under drywall - and between the drywall and studding. It reduces noise in the walls by some claimed large factor.

• The thing is the wall is only made of 2 mm thick stainless steel, nothing else. Besides noise insulation there is going to be thermal insulation in that wall - the goal is to make it all together as thin as possible with as good audio and thermal isolation as possible, in 10 cm total. Maybe there are some materials which provide both audio and thermal insulation at the same time, so the 10 cm available thickness can be used most efficiently? – ria May 2 '11 at 16:51
• I would just put an extra layer of drywall with an air gab and something to isolate the new layer from the studs (some sort of foam gasket under the nails?). Drywall-air-drywall should be pretty good. – mgb May 2 '11 at 16:59