Non-exponential decay curves in reverberation chambers
* Presenting author
ISO 354 Annex D gives recommendations to increase the diffusivity in reverberation chambers by installing diffusers. The absorption coefficient of a sample will be increased with the amount of diffusers until it reaches a maximum value. This paper discusses the reasons for the increase of the absorption coefficient and how this can influence the interlaboratory reproducibility. When an absorber is placed on the ground without any diffusing elements in the room, the energy decay will exhibit a non-exponential nature at mid and high frequencies due to the resulting vertical and horizontal sound field. Calculating the reverberation time with linear regression is questionable in those cases. Measurement results with varying number of diffusers will be discussed showing that the slopes of the inital and late part of the energy decay as well as the bending point are changed.