In This Section
Reflecting on Reflections - June 2014
Audibility of a CD-Standard A/DA/A Loop Inserted into High-Resolution Audio Playback - September 2007
Quiet Thoughts on a Deafening Problem - May 2014
AES Conference Papers Forum
Active Acoustic Absorbers Revisited
This paper continues an earlier exploration of using low-frequency loudspeakers as acoustic absorbers, with absorption cross-sections that far exceed their geometric size. Theory for a point active absorber immersed in the acoustic field of a point source is reviewed as it would apply to normal loudspeakers used as either sources or absorbers at low frequencies for which they act as compact sources. This theory contains an extra problematic term, which is suppressed if averaged over frequency or distance. In rooms, such suppression is expected due to the varying distances from all the source images to the absorber. Impulse responses in several small rooms were measured from a few sources and absorber loudspeakers to both a few listening microphones and near-field microphones mounted at the absorbers. These data were used to implement active absorption. The efficacy of the active absorber is assessed and the results are somewhat enigmatic. A room simulation was done to check on the actual measurements, and results are similar to theoretical expectation. The discrepancy should perhaps be attributed to the rather complex implementation issues.
No AES members have commented on this paper yet.
Subscribe to this discussion
Start a discussion!
If you are not yet an AES member and have something important to say about this paper then we urge you to join the AES today and make your voice heard. You can join online today by clicking here.