Spaced object absorbers, sound absorption coefficients, and the noise reduction coefficient rating in architecture

Abstract

Spaced object arrays (e.g., vertical baffles) are a growing trend for reverberation time reduction in architectural spaces. Unfortunately, the acoustical considerations for these products are significantly more complex than traditional continuous ceiling treatments. Architects and designers are familiar with sound absorption coefficients (Sabins/ft2) and the NRC Rating, but these are technically not applicable to spaced object arrays. Further, product manufacturers consider the correct Sabins/Object over 1/3 octave bands to be too technically complex for marketing purposes. The ASTM E33 committee is currently exploring ways to create a single number rating for spaced object arrays. A status update of proposed revisions to ASTM C423 will be shared. IP Units are substituted for SI Units in this abstract for the sake of clarity. [Eric Wolfram serves as Laboratory Manager for Riverbank Acoustical Laboratories and is currently Chair of the ASTM E33 Committee on Building and Environmental Acoustics. https://www.astm.org/COMMITTEE/E33.htm]