Sound Absorption

[cvengr]

Question:
What common commodities are best utilized to insulate the listening room from sound leaking out and disturbing neighbors and technically what expressions might be used to quantify and qualify that dampening?

I'm interested from a mathematical perspective in calculating frequency absorption at various sound intensities, for different density and thickness materials.

For example, foam panels are great simple solutions,...if I happened to have several freight cars of gold bullion to trade, ...but instead, egg crates might be preferable. Since egg crates might not have the aesthetic value and are easily deformed plastically, I might consider using the egg cartons as forms for foam or concrete, then isolate the panels by other mechanisms at specific frequencies.

My search is to find some general equations expressing how to isolate a room for sound listening from adjacent rooms and to prevent disturbance to neighbors.

Any textbook recommendations?

Thanks in advance.

[Mr. Widget]

Question:
What common commodities are best utilized to insulate the listening room from sound leaking out and disturbing neighbors and technically what expressions might be used to quantify and qualify that dampening?

I'm interested from a mathematical perspective in calculating frequency absorption at various sound intensities, for different density and thickness materials.The unit of measure is the Sabin... however to lessen the sound going through a wall, Sonex foam or mattresses will not do that much. Coating the interior walls with absorptive material will dramatically affect the sound in the room, but sound will go through it and get transfered by the framing to the other side of the wall. Do some Google searches. There is no magic bullet solution. You probably can find equations that will give you a ball park idea of the sound transfer, however since rooms are complex and the number and type of windows will affect the result as will the type and quality of the construction, I doubt anything short of a computer model will do you any good. Your problem is a fairly simple physical one. Essentially you need to de-couple the room from the exterior of your house. This can be done as completely or as minimally as your budget permits. Look at recording studio construction and other websites discussing noise control.

Check out QuietRock:

http://www.quietsolution.com/html/quietrock.html

Also, if you are going to redo or add in-wall insulation, use cotton instead of fiberglass. There is a product made from recycled denim jeans. It is sold in a variety of R values and is significantly better at reducing noise transmission. It has the side benefit of not making your skin itch too. Here is one brand:

http://www.ecoproducts.com/Building/build_insulation/build_cotton_insulation.htm

Good luck, your task isn't an easy one.


Widget

[ratitifb]

Coating the interior walls with absorptive material will dramatically affect the sound in the room, but sound will go through it and get transfered by the framing to the other side of the wall.absorption vs transmission loss : for a simple wall the sound loss index increases by 6dB (4dB in practice) each doubling of mass or frequency.

Double wall (two panels separated by a thin layer of air or porous marerial) allows to increase strongly the sound loss index compared to double the wall thickness (paradox of double wall).

Very interesting site :

http://irc.nrc-cnrc.gc.ca/pubs/bsi/85_e.html

[Fred Sanford]

This is helpful & well-structured info, but keep in mind it's written/hosted by a company that wants to sell you their product:

http://www.acoustics101.com/

[cvengr]

absorption vs transmission loss : for a simple wall the sound loss index increases by 6dB (4dB in practice) each doubling of mass or frequency.

Double wall (two panels separated by a thin layer of air or porous marerial) allows to increase strongly the sound loss index compared to double the wall thickness (paradox of double wall).

Very interesting site :

http://irc.nrc-cnrc.gc.ca/pubs/bsi/85_e.html

See appendix A It has some useful equations.

Here's an interesting bit of acoustic pornography:

http://www.cedia.net/awards/past_awards.php

[ratitifb]

yep :blink: i don't find appendix A ? Could you post the link ;)

[richluvsound]

This stuff gets great press !
inexpensive and easy to use

http://www.greengluecompany.com/

Rich

[duaneage]

These guys are experts

http://www.acoustilog.com/

Navigate through their site to areas about home and residential and they have tips and situations.

But you can take steps simply to minimize transmissions. If your willing to do construction, a 6 inch thick wall with staggered 2x4 construction and interwoven fiberglass will reduce noise a lot, dual layers of drywall reduce it even further. Sound is energy and if your running at disco levels next to a church your not going to find magic solutions. Speaker placement matters as much, source material matters too. Sometimes the best solution is to just move somewhere else to a single family home.

[louped garouv]

These guys are experts

http://www.acoustilog.com/

Navigate through their site to areas about home and residential and they have tips and situations.

But you can take steps simply to minimize transmissions. If your willing to do construction, a 6 inch thick wall with staggered 2x4 construction and interwoven fiberglass will reduce noise a lot, dual layers of drywall reduce it even further. Sound is energy and if your running at disco levels next to a church your not going to find magic solutions. Speaker placement matters as much, source material matters too. Sometimes the best solution is to just move somewhere else to a single family home.

the guy that runs that business is a living legend IMO...

he made some really neat club and studio gear in addition to his acoustic treatment wizardry

[cvengr]

yep :blink: i don't find appendix A ? Could you post the link ;)

Same as the link you posted, just at the bottom of the page.

[ratitifb]

Same as the link you posted, just at the bottom of the page.ok, I have forgot to delete my post when I realized that A = 1 ;)

[sonofagun]

Best materials/construction is probably similiar to the best materials for building enclosures - non-resonant, sound deadening/absorbtive.

Concrete has been touted for enclosures for years - the denser/heavier, the better.

Bet you can play music pretty loud inside a nuclear blast shelter w/o disturbing the neighbors! :blink:

[gedlee]

The room issolation problem is very tricky. The first point that should be made has been made and that is that there is a big difference between sound absorption and low sound transmission. In general you want the opposite materials for these two things. Concrete walls are great for low sound transmission but are very good sound reflectors. In fact to not transmit the sound it is best to reflect it since absorbing it tends to be a loosing proposition.

I will point out that I have a book that has an entire section on noise control and simple means for effecting this in your home. Its written for the DIY, and I'm not selling any products, although I do sell the book. But you asked for a book reference. I won't post a link directly, but you can easily get to my website with Google, etc.