This week's demonstration/discussion session complements the general "volumetric" spatial audio model introduced at the last meeting. We will start by listening to some of the more unusual results obtainable from our steerable beam, spherical array and discuss the various models that have proposed to actualize spatial audio. It is likely that economic constraints and the reductive tradition of psycho-acoustics will continue to require compromises in the resources to synthesize spatial scenes as we have seen in the idea that one can do stereo with a single subwoofer and high frequency pair. We will survey the kinds of compromises already codified in various industries and discuss the possible opportunities for efficient implementations that still afford interesting applications of spatial audio systems.