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Completed Project

Effect of Sound-Scattering Surfaces on Sound Field Diffusivity in a Real-World Classroom

Ariana Sharma, Vassar College ’16, Mohammed Abdelaziz, Vassar College ’16 and Prof. David T. Bradley

In an ideal diffuse sound field, all acoustic properties are independent of position (homogenous) and invariant with respect to direction (isotropic). Sound diffusers, surfaces with a non-planar geometry that reflect sound in a non-specular direction, can be installed in acoustically sensitive rooms to increase and/or control the field diffusivity. Predicting, characterizing, and controlling diffusivity is essential to acousticians when designing and using acoustically sensitive spaces. However, although some theoretical and computational modeling work has been carried out to better understand the effect of installing diffusers on the resulting field diffusivity, the current state-of-the-art does not include a clear and systematic understanding of this effect. Furthermore, very little work has been done to characterize this effect in real-world spaces. In the current project, an increasing number of diffusers have been installed in a full scale, real-world classroom: Kenyon 134 on Vassar College’s campus. Field diffusivity has been measured for various configurations of the diffusers using two measurement techniques: 1) a linear three-dimensional microphones grid used to characterize homogeneity, and 2) a spherical microphone array used to characterize isotropy. Results and analysis will be presented. It is anticipated that the measured data will aid in achieving the long-term goal of developing an objective measure that characterizes both the homogenous and isotropic aspects of sound field diffusivity. This material is based upon work supported by the Paul S. Veneklasen Research Foundation under Grant No. 13.09, and through collaboration with Acoustics First Corporation and VisiSonics.