Materials, Building Components and Structure Testing
Scattering and Diffusion
The absorption parameter is used to calculate the reduction of energy in the room. Scattering can also be used to do the same thing but is also used to indicate the percentage of energy that is randomly reflected back into the room versus the energy reflected in a specular way.
Absorption had well known test procedures that were later standardized to create the parameter, "absorption coefficient", but scattering coefficients were inserted into the programs and "tweaked" by users based on "experience" This method was better than nothing as long as measurements were not available and standards had not been developed.
This ended with the adoption of ISO-17497-1
The standard, ISO17497-1, was developed in Europe. It was based, primarily, on research conducted by Vorlander and Mommertz using a free field method. This was later converted to a method that used a reverberation room instead. Initially all research and measurements were done using scale models of the scattering surface. NWAA Labs was the first research and testing facility to develop a "FULL SCALE" method to perform scattering tests. There were numerous initial problems converting the scale model method to full scale but Ron Sauro made breakthroughs developing "corrected" procedures to get consistent and repeatable measurements of the full scale samples.
Our clients insist that the scattering data NWAA Labs has already delivered to such companies as Armstrong World Industries, MBI, Pyrok, Wenger Corporation, and Auralex Acoustics has provided insight into their products' performance -- and that allows for not only finer-tuned development, but also better informed marketing and business decision making.
Even though NWAA Labs normally uses the standard test procedures described for testing, Ron is constantly trying to improve or create better ways of measuring relevant acoustic parameters.