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I need an enclosure to block outside noise by about 30 to 40 DB. The noise I'm most interested in blocking are in the 0 to 2000 Hz range. I understand that mass is important for blocking (insulating) noise. Here's my proposal:

On a table top, place a sheet of acoustic foam or rubber sheet. Place a 1/2 inch thick steel plate on top of the acoustic foam or rubber sheet to serve as my bottom layer. Place a 1mm or 2mm rubber or silicone sheet on top of the steel plate to serve as a seal for my enclosure which is composed of a 5 sided box.

I would like to use acrylic for the 5 sided box because transparency is an advantage for my application and it's easy to buy a custom acrylic 5 sided box rather than making my own (like using MDF). The thickness will be 1/2 inch. To further enhance sound proofing, I would to use TWO 5 sided acrylic boxes each being 1/2 inch thick sized such that there will be a 1/2 thick air gap between the 5 sides between the inner and outer box. Both boxes will be placed on the steel bottom layer with a rubber sheet in between for an airtight seal.

Another option is to use a 1 inch thick Delrin or acrylic plate rather than steel for the bottom layer. I need to drill a hole for placing a wired microphone inside the box and plastic is easier to drill than steel.

Would this cause a lot of echo in the box? I will have a microphone inside the box to record the sound of a object placed inside the box. I wonder if echo will cause issues.

Thanks

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  • It really depends on the size of the box, which you didn't specify… but imagine you put a bucket over your head & speak... – Tetsujin Aug 17 '20 at 15:25
  • so putting some acoustic foam inside will help? – user173729 Aug 17 '20 at 18:29
  • Acoustic foam will modify the decay of some frequencys and the frequency response of the box and the microphone. Whether it helps is a larger question - help with exactly what? – ghellquist Aug 18 '20 at 5:13

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