The Reflection Phase Grating Diffusor: Design Theory and Application
The far-field diffraction theory of the Schroeder reflection phase grating diffusor, which provides broad-bandwidth wide-angle coverage, is reviewed. Design parameters are discussed, and theoretical diffraction patterns are presented for a quadratic-residue and a primitive-root example. The diffraction patterns are obtained using a new reflection phase grating program, which was developed to facilitate the design and evaluation of these acoustical diffusors. Experimental energy-time curves are presented and discussed for two models. A few recording studio applications are mentioned, and a recent installation is pictured. Observations in recording control rooms suggest that the reflection phase grating diffusor helps maintain the stereo perspective across the width of the mixing console and adds the sweetening of a concert hall to a treated room.
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