Reply
 
Thread Tools Display Modes
  #1   Report Post  
Posted to rec.audio.pro
Sean B Sean B is offline
external usenet poster
 
Posts: 31
Default Adding Multiple Absorption Coefficients

Hello,

So let's say I have two different acoustic absorbers covering most of the area of a room, say a bass absorber and a higher broadband absorber. They cross over at around 250 Hz. If both have a 0.5 absorption coefficient at 250 Hz, how do I calculate a total absorption figure for both acting at the same time?



Thanks,

Sean B
  #2   Report Post  
Posted to rec.audio.pro
Scott Dorsey Scott Dorsey is offline
external usenet poster
 
Posts: 16,853
Default Adding Multiple Absorption Coefficients

Sean B wrote:

So let's say I have two different acoustic absorbers covering most of the a=
rea of a room, say a bass absorber and a higher broadband absorber. They cr=
oss over at around 250 Hz. If both have a 0.5 absorption coefficient at 25=
0 Hz, how do I calculate a total absorption figure for both acting at the s=
ame time?


A square foot of a thing with a 0.5 absorption coefficient has the same
effectiveness as half a square feet of open window (which has an effectiveness
of 1.0). If you have a thing with a 0.25 absorption coefficient, you will
need four square feet of it to get the same effectiveness as a square foot
of open window.

Multiply the absorption coefficient of all the materials in the room by the
area of each of those materials, sum them up and get the total room absorption.
In a larger room you can plug this into the sabine equation and get the
reverb time of the room. In a smaller room where you don't care about the
total reverb time so much as specific room resonances, it's a little harder
but the relevant equations are in the F. Alton Everest book on small studio
acoustics.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #3   Report Post  
Posted to rec.audio.pro
Phil Allison[_4_] Phil Allison[_4_] is offline
external usenet poster
 
Posts: 499
Default Adding Multiple Absorption Coefficients

Sean B wrote:

-------------


So let's say I have two different acoustic absorbers covering most of the area of a room,


** What area is that?

All six surfaces with two independent absorbers ?

Not very realistic.


say a bass absorber and a higher broadband absorber. They cross over at around 250 Hz. If both have a 0.5 absorption coefficient at 250 Hz, how do I calculate a total absorption figure for both acting at the same time?


** The figures applies to the absorbers, not the room.

Nothing changes if one sits over the other.



...... Phil

Reply
Thread Tools
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Sound absorption in air. WillStG Pro Audio 3 January 13th 06 10:06 PM
Sound absorption in air. Chris Whealy Pro Audio 2 January 12th 06 03:23 PM
Sound absorption in air. Phil Allison Pro Audio 0 January 12th 06 12:30 AM
Tascam US 122 and Adobe Audition - Multiple Sources to Multiple Tracks [email protected] Pro Audio 5 September 29th 05 01:41 PM
Multiple Input to Multiple Output Video (Muliplextor/Splitter) Ben Nguyen Pro Audio 2 October 25th 03 04:28 AM


All times are GMT +1. The time now is 08:50 AM.

Powered by: vBulletin
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AudioBanter.com.
The comments are property of their posters.
 

About Us

"It's about Audio and hi-fi"