Tweakers' Asylum

Posted by robertopisa (A) on April 27, 2007 at 15:16:17

I use foam panels for absorbing sound, and it usually comes 2cm thick or more.

Is there any thinner material (say 0.5cm) that is as flexible and sound absorbing as foam? I cannot use thick foam and cutting foam into thin slices probably does not help.

Thanks
Roberto

• Probably not… - David Aiken 23:44:41 04/28/07 (3)
  In Reply to: sound absorbing posted by robertopisa on April 27, 2007 at 15:16:17:

  If there was, everyone would be using it. The reason acoustic treatments tend to be thick is that thick is more effective than thin. Thick has problems like appearance, and fitting it in to some rooms and the like so if there was an effective thin material, manufacturers would be offering commercial products utilising it, even if they came at a price premium.

  Vibration damping materials like the ones HumanMedia suggested aren't intended for acoustic use, and the thin foam panels he suggested are intended to work in the small, enclosed space of a computer cabinet with reflective metal walls which they damp. Sound will tend to be reflected inside the cabinet because of the metal walls and the reflective path is short because of cabinet size. As a result the sound gets reflected many times and meets a thin sheet of foam each time, but many reflections means that the sound passes through that thin sheet of foam twice on each reflection (in and back out) and does it many times. That effectively adds to the equivalent of a much thicker foam layer. In a larger space like a room with a much longer reflection path, thin foam will only be effective at the highest frequencies and that isn't too helpful. You really want absorption over a much wider bandwidth for the best results.

  Even your 2 cm panels are relatively thin and you would get better results with thicker panels than that.

  I realise that this isn't what you want to hear but unfortunately it's the way things are. You can try the foam computer case damping panels HumanMedia suggests, or something similar, and you will get some absorption but if all of the absorption you are getting is at the highest frequencies, and that is going to tend to be the case, you are likely to end up with a room that sounds dead because it's lost the highest portion of the reflected sound but the bass and midrange reflections are totally untouched. The ideal is uniform absorption across the whole audible bandwidth and while no material gives that, getting absorption over as wide a bandwidth as possible does yield noticeably better results. Unfortunately you need thickness to get effective absorption at mid-range frequencies and below.

  David Aiken
  
  

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  • Re: Probably not… - robertopisa 11:57:25 04/29/07 (2)
    In Reply to: Probably not… posted by David Aiken on April 28, 2007 at 23:44:41:

    Thanks David for the clarification. I do not need to treat my listening room (which I already did with thicker foam and panels) but some small device. That's why I need a thin damping (better than nothing...).

    Bests
    Roberto
    
    

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    • Re: Probably not… - David Aiken 13:16:35 04/29/07 (1)
      In Reply to: Re: Probably not… posted by robertopisa on April 29, 2007 at 11:57:25:

      You didn't mention the purpose in your original post.

      For absorbing soud from a small device, the foam panels intended for computer use should be helpful but they will be more effective inside rather than outside. Inside, they absorb each time a reflection falls on them. Outside, sound escaping from the case is going to go through them once only on exit and then get reflected around the room. Yes, some reflections from the room will eventually strike the case again but the case is small in comparison to room area so that won't happen too often.

      If you can't fit the foam or whatever you use inside the device's case, can you build a small cabinet to enclose the case and line the inside of the cabinet instead?

      David Aiken
      
      

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      • Re: Probably not… - robertopisa 04:17:45 04/30/07 (0)
        In Reply to: Re: Probably not… posted by David Aiken on April 29, 2007 at 13:16:35:

        Thanks David. I forgot to specify that I'm damping a small device (usb soundcard) in the first post. Using an external case could help, but I would like first to see if this works. I'm also using Blue Tac.

        Cheers
        Roberto
        
        

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• Re: sound absorbing - HumanMedia 20:35:25 04/27/07 (1)
  In Reply to: sound absorbing posted by robertopisa on April 27, 2007 at 15:16:17:

  I dont know if it would suite your needs, but I love the following stuff which has adhesive backing. I use to dampen just about every component.

  http://www.quietpc.com/nz/materials.html

  This Soundcoat stuff is similar, not as effective but much thinner and maybe better for your needs.

  http://www.partsconnexion.com/catalog/dampingmaterials_isofeet.html
  
  

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  • very helpful, thanks (nt) - robertopisa 16:52:42 04/28/07 (0)
    In Reply to: Re: sound absorbing posted by HumanMedia on April 27, 2007 at 20:35:25:

    nt
    
    

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