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# Physics: Determining Sound-Absorption Coefficient (1 Viewer)

#### Darren Davis

##### Stunt Coordinator
I'm working on a science project where I measure the dBs lost in a box lined with certain materials and I think I'd like to incorporate the coefficient of sound-absorption for the different materials in the project. I've looked through my physics II book (nothing found) and checked out google but the sites seem either for construction or other physics lessons where the coefficient is merely mentioned. I'd like maybe some good physics websites that can go a little more in-depth with the subject. Nothing too advanced but I'll take from beginner to whatever level you think a fairly smart 11th grader could handle.
I'd like to be able to experimentally find the coeffiecents for a few different materials and then compare with the originals (yay, teachers love error analysis). I've done another project in which I found the coefficient of static friction and I figured through manipulation of the formula and determination of the other variables the sound-absorption coefficient can be found similarly.
Thanks for any help.

#### Grant B

Senior HTF Member
Darren
Sounds like a good project. I have a book, Sound Reinforcement Handbook;Written for Yamaha By Gary Davis & Ralph Jones (2nd Edition)
Page 54 gives a fairly good explanation and table for about 20 materials (Example: Carpeting (with pad) .10 .30 .70 @ 125 1k and 4KHz). An open window- which does not reflect any sound is considered theperfect absorber and has a coefficient of 1 (100%)
A perfect reflective surface is 0.
Email me if you cant find it in a library/web - its too much to even paraphrase here.

Have you tried the society of accoustical engineers?
I remember the web site had a lot of good info
Try those and if you strike out let me know
Good Luck
Grant

#### Darren Davis

##### Stunt Coordinator
hey, Grant B, sorry about not replying for a while. I got so busy for a while there I almost completely forgot about this thread. I was able to get some help from my teacher and from some online sources and earlier this week turned in my 20+ page lab report and gave a presentation on it on wednesday night. Your post did help me, however; I got a better grasp on some stuff. So, thank you very much for helping me.
Ahhh, I'm so glad this week is over. This coming week is an easy week, only final exams.
Once again, thank you!

#### Grant B

Senior HTF Member
Darren

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