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Last week I was asked “Is there an carpet acoustic treatment you would recommend? Is there such a thing?” Well I’ve never heard of anything. This is a new one to me. People and companies attach the word acoustic to almost anything. Just remember that there’s only three things that happens in sound, it’s absorbed, diffused or reflected.

Let’s forget about reflected energy because that’s what everything does. So our sources of treatment are diffusion and absorption. Now carpet by definition is a sound absorbing material. It’s loose, its fibrous, air can move through it, if air moves through it we have friction, we have heat, we have an energy transformation.

So I guess companies attach the word acoustic onto it because they want to sell it as something that’s related to sound but all carpet is a sound absorbing material. So that said, how much absorption occurs and at what frequencies does it occur? Well it’s very thin, well most of it.

So we know we’re not going to get any low-frequency absorption by definition, the laws of physics tell us something one inch thick is not going to absorbing any low frequency energy and that’s true. Now there’s middle and high frequency absorption. As a general rule a human being has about the same absorption qualities as twelve square feet of carpeting. So that would give you an idea of how powerful carpet is in terms of absorbing because human beings are just big bags of water so the sound absorption coefficient that a human being would represent is about the same as twelve square feet of carpeting.

So that’ll give you some guidelines but I’ve never seen absorption coefficients published on carpet so acoustical carpet I think that’s just mainly a marketing term.

Middle and high frequency absorption and low-frequency absorption are completely different animals, completely different science, completely different technologies, completely different approaches. Low-frequency management has its own set of issues. Middle and high frequency absorption has it’s whole set of issues also. So you can’t confuse the two and please don’t.

A lot of companies go out of their way to add to that confusion and hopefully the things that we say here and publish on our website and the new videos that we do, go a long way to helping people understand those differences.

In Summary

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Dennis Foley

I am an acoustic engineer with over 30 years’ experience in the business. My technology has been used in Electric Lady Land Studios, Sony Music of New York, Cello Music and Films founded by Mark Levinson, and Saltmines Studios in Mesa, Arizona, along with hundreds of others.

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