1) At this time there is no standard method of testing corner absorption.
2) Absorption measurements below 100 Hz have an increasing level of error due to the inability of a test chamber to maintain the same level of diffusion of very large sound waves as is present with smaller waves.
3) This test uses only 8 linear feet of corner for testing and would not be suitable for comparison to tests taken with larger specimens counts as the smaller than typical sample size used in this experiment would tend to exhibit higher absorption numbers than a test with a larger sample size. Nonetheless, these tests are valid comparisons of the included specimens. All of the data sets below were collected in the same configuration for each specimen set, in the same lab, on the same day.
What does this test show?
1) All 3 absorbers have considerable low frequency absorption.
2) Acoustic Foam has low frequency absorption performance comparable to mineral wools.
3) Porous absorbers achieve enhanced effectiveness when corner mounted.
4) This test also leads to many new questions.
Attached and depicted below are results derived from a series of tests conducted at Riverbank Acoustical Laboratories on four common approaches to providing absorption in that most critical of room locations... namely the corner. These tests and the sharing of the resultant data with the public has been orchestrated by our esteemed forum member here at http://forum.studiotips.com, Jeff D. Szymanski. Jeff is the Chief Engineer at Auralex Acoustics and he and his firm deserve a big round of applause [and wolf whistles] from the peanut gallery for this public service.
Jeff.. Auralex... we salute you.
This data was collected as the result of a request / challenge made by me some months ago to Jeff. After thousands of posts discussing various means of addressing the need to install absorption devices in the rooms we help design and build, we needed some laboratory grade test data comparing apples to apples as to some of the common absorption devices. Auralex Acoustics, at Jeff's behest, has come to the fore, Let the scales fall from your eyes brethren, arise from the depths of ignorance and go forth into the corner of thy room and slay the dragons of LF resonance with a sword of knowledge in thy mighty hand.
While you peruse the below-listed, please also give thanks to Eric Desart for helping to correlate the data and validate the processes involved.
This information is presented in a fashion to allow a designer / builder to rationally estimate the result of choosing between these four devices [edit: one of the devices has been removed from this side-by-side comparison test at the request of its designer, Ethan Winer] and the impact such choices will have on the acoustic characteristic of the finished room. The MegaLENRD is a commercially sold product made by Auralex that requires minimal effort to install [just stack them up]. The other two devices - the StudioTips Corner Absorber & the StudioTips SuperChunk - are DIY [do-it-yourself]designs that evolved from discussions here at the StudioTips forums and will be familiar to our membership.
For more information on these devices please surf these links:
http://www.auralex.com/bass_traps_mg-le ... -lenrd.asp
The picture below is just the graph of the data [that's all that will fit at a legible size].
Note: this graph expresses Imperial Sabines, NOT Metric Sabines.
For a look at the raw data together with various links and credits please download the excel file.
Also attached is a sketch by Eric Desart which shows the position relative to the "corner", and the dimensions of the devices.
Document © 2004 http://www.studiotips.com
Data © 2004 Auralex Acoustics, Inc