.

sorry ,wrong topic, preparing a new post for garage studio construction.

research is your friend

Bradley, J.S.; Lay, K.; Norcross, S.G. Measurements of the Sound Insulation of a Wood Frame House Exposed to Aircraft Noise, Internal Report, Institute for Research in Construction, National Research Council Canada, (831), pp. 113, March 01, 2002 (IR-831) URL: http://irc.nrc-cnrc.gc.ca/pubs/ir/ir831/ Warnock, A.C.C. Controlling the Transmission of Airborne Sound through Floors, Construction Technology Update, 25, pp. 4, May 01, 1999 URL: http://irc.nrc-cnrc.gc.ca/pubs/ctus/25_e.html Nightingale, T.R.T.; Quirt, J.D.; King, F. "Guide for flanking sound transmission in wood framed construction - airborne sources," Proceedings of 14th International Congress on Sound and Vibration (Cairns, Australia, July 09, 2007), pp. 1-6, July 09, 2007 (NRCC-49468) URL: http://irc.nrc-cnrc.gc.ca/pubs/fulltext/nrcc49468/

thanks

you won't fries wid at?

If the walls already exist, just measure the reverberation in the room. That's sort of what Sabine would have done. The walls themselves alone don't dictate what other absorption you will be needing, the size and symmetry of the room also factors in.

http://www.saecollege.de/reference_mate ... 0Chart.htm http://www.wsdg.com/dynamic.php5?id=res ... absorbtion http://www.gmi.edu/~drussell/GMI-Acoust ... ption.html http://www.greengluecompany.com/soundAbsorption.php http://www.auralexelite.com/resource_ce ... ossary.asp http://en.wikibooks.org/wiki/Engineerin ... cert_Halls etc etc

Absorption coefficients are measured not calculated. Well, you can always bring a piece of your wall to an acoustic lab. :wink: In meantime here's two tables calculated from the top of my head: "wall 1" 125hz 250hz 500hz 1000hz 2000hz 4000hz 0.14 0.1 0.06 0.05 0.04 0.04 "wall top 2" 125hz 250hz 500hz 1000hz 2000hz 4000hz 0.02 0.27 0.63 0.85 0.93 0.95 Not that they're helpful. (If you've done your homework properly, you will catch my drift.)

I'm lost when it comes to acoustics numbers, but I do have a question that hopefully is on topic. Based on the design of the wall and ceiling above, how much will flanking change those numbers when trying to establish them? With hard coupling of the ceiling skin, no noticeable damping in wall or overhead and thin skinned walls anyway...I know this lowers isolation ability but what affect does it have as it applies to picking additional building and acoustic materials?

dahnielson wrote:

If the walls already exist, just measure the reverberation in the room. That's sort of what Sabine would have done. The walls themselves alone don't dictate what other absorption you will be needing, the size and symmetry of the room also factors in.

Thank you Anders,

thanks

Just build some traps and hang them on the wall. SuperChunks in the corners. Possibly a bas trap at the back wall. Normal treatment. Unless you by "dead" mean an approximated free-field condition? That's all I can say. And it's impossible to say anything about the ceiling absorption since you haven't provided any specific data about the mineral wool. What pcf? What kind mineral wool? The slabs thickness (3/4" ?) ? Or more specific any useful and measured acoustic data about the mineral wool (the suppliers can probably provide absorption coefficients for them).

thank you

timogiodeson wrote:

OK but why? All that work for a corner?... Please explain to me, 4 superchunk's? or 4 full walls and a ceiling with 3 1/2 " R insulation? Which will absorb more bass?

4 full walls with 3 1/2" rigid insulation mounted at 3 1/2" distance from the wall. But 90 degree (or less) corners are acoustically generally never good.

timogiodeson wrote:

by dead I mean that as a starting point I don't want any reflective surfaces around , Period!

Well, if you're really serious: http://www.bruel-ac.com/tr/tr9602/tr9602.html http://www.bruel-ac.com/tr/pi9701/PI9701.html ;)

timogiodeson wrote:

The density of the rigid mineral wool is about 22 pounds PCF just like generic acoustic ceiling tile NRC 0.55, thickness 5/8 ... not too bad axially.

The NRC is an average, good for general RT60 calculation, but doesn't tell you anything about specific frequencies. http://www.ethanwiner.com/acoustics.html#sb3 What I previously, rather cryptically, hinted at was the fact that if you really want some absorption coefficients just use the outermost layers coefficient. Two layers of drywall or mineral wool will probably not mean that the coefficient will double, but it will at least in the mineral wool case increase even tough two layers of 2" mineral wool probably will not be absolutely equal to one layer of 4" but close.

dahnielson wrote:

4 full walls with 3 1/2" rigid insulation mounted at 3 1/2" distance from the wall........ But 90 degree (or less) corners are acoustically generally never good... Well, if you're really serious:.............

Wow, great links! Thank you.

if you build the corner traps - superchunk style or spanning the corner with 4" 3pcf rigid insulation, you'll have a bunch of absorption for quite a range (called broadband trapping). then on the walls and ceilings, place some absorbers (say 2'x4'x4") about 2' apart so you have absorption and wall. make the opposite walls staggered so wall reflects to absorber. on the ceiling, just space the absorbers about 1' apart over the kit. see what happens, you can add more absorption if you need it. you really don't want a dead room for drums... you could also build some slats across the corners to change the wall angles plus add absorption without making the room dead. then you could still add porous absorption to deaden it when needed. http://img444.imageshack.us/img444/6908/petercrosbierender1gw3.th.jpg http://img440.imageshack.us/img440/691/pearlsnaprendertz6.th.jpg http://img442.imageshack.us/img442/1661/alejorendersp6.th.jpg http://img144.imageshack.us/img144/4297/alejotg7.th.jpg http://img184.imageshack.us/img184/6566/petercrosbierender2fe9.th.jpg

timogiodeson wrote:

Wow, great links! Thank you.

I'll pass it on to AVare who posted them in the first place. :)

gullfo wrote:

if you build , .............................. http://img444.imageshack.us/img444/6908/petercrosbierender1gw3.th.jpg http://img440.imageshack.us/img440/691/pearlsnaprendertz6.th.jpg http://img442.imageshack.us/img442/1661/alejorendersp6.th.jpg http://img144.imageshack.us/img144/4297/alejotg7.th.jpg http://img184.imageshack.us/img184/6566/petercrosbierender2fe9.th.jpg

Thanks, very inspiring images.