Enhancement of virtual acoustics rendering using boundary mounted dipole loudspeakers

Abstract

The Immersive Media Lab at McGill University hosts a Virtual Acoustics Technology (VAT) system incorporating a suspended array of omnidirectional loudspeakers. Using a convolution reverb engine, acoustic simulations of real spaces can be realized via a catalog of Room Impulse Response measurements. Reflected sound in the room helps to disguise the location of the sound emitters rendering virtual acoustics. One limitation of the system, however, is the interference between the lab’s natural acoustics and the virtual environment generated by the VAT system. The improvement under consideration is to enhance diffusion along the walls of the lab, in order to mask the acoustical characteristics related to the physical dimensions of the room. Dipole loudspeakers are installed on the room boundaries and used to scatter reflections and reverberation along the wall surfaces enlarging the effective radiation surface of the walls. The scattered energy may mask specular reflections and reduce localization of the virtual acoustic sources. Investigations compare the result of scattering reflected sound vertically as opposed to horizontally across the boundaries. Measurements illustrate the effect of the dipole loudspeaker system when used on its own as well as working in conjunction with the existing omnidirectional loudspeaker array.