Decay curves in coupled, reverberant spaces

Jamilla Balin, Melanie Nolan, Efren Fernandez Grande, Jonas Brunskog, Cheol-Ho Jeong, Ning Xiang, Gerhard Graber

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review


This study investigates the effect of panel and boundary diffusers in a reverberant space. Diffusers
are usually mounted in a reverberation chamber to increase the diffuse sound field as
recommended in Annex A of ISO 354. The ISO is not specific about the location or the material
of the panels; the standard only states that the absorption coefficient of a highly absorbing
material will increase and approach a maximum value. This value is usually much higher than
1 when diffusers are added. It is also known that the reproducibility of absorption coefficient
measurements in reverberation chambers is unsatisfying. This study investigates the effect of
panel diffusers, in particular considering that their dispositioning in a room can create coupled
spaces, decreasing the effective volume of the chamber, and leading to an overestimation of the
absorption coefficient. The decay curves are measured in a small chamber with panels placed in
a corner creating a coupled space. Both in the empty room as well as with A = 3 m2 absorbing
porous sample on the floor, the decay curves are evaluated. Additionally, the effect of boundary
diffusers is considered. The decay curves for different room configurations in the occupied
(with high absorption on the floor) and unoccupied state (without any absorption) are compared.
The decay curve in the occupied state without any panels or boundary diffusers has a breakpoint
where the slope changes its value. This can also be observed in the unoccupied state with panels
placed in the corner of the room.
Original languageEnglish
Title of host publicationProceedings of 22nd International Congress on Acoustics
Number of pages10
Publication date2016
Publication statusPublished - 2016
Event22nd International Congress on Acoustics : Acoustics for the 21st century - Catholic University of Argentina, Buenos Aires, Argentina
Duration: 5 Sep 20169 Sep 2016


Conference22nd International Congress on Acoustics
LocationCatholic University of Argentina
CityBuenos Aires
Internet address


  • Reverberation chamber
  • Absorption
  • Diffusivity
  • Diffusers


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