Spatial soundfield reproduction in complex environments

Abstract

Personalized sound environments are becoming increasingly important to the entertainment and audio industries. Using spatial multizone soundfield reproduction, an individual sound environment can be produced to each listener inside an enclosure without physical isolations or the use of headphones. Realization of such a multizone soundfield reproduction system is a conceptually challenging problem in acoustic signal processing, as currently most of the existing techniques concentrate on a single zone. This thesis considers the theory and design of a soundfield reproduction system using arrays of loudspeakers in given complex environments including multizone and reverberant environments. Cylindrical harmonic and spherical harmonic analysis are used to provide mathematical descriptions of spatial soundfields. A continuous loudspeaker concept is first developed to overcome the limitations of existing single-zone soundfield reproduction techniques. Three novel approaches to achieve spatial multizone soundfield reproduction are presented. In the first approach, a generalized framework on 2D (height-invariant) multizone soundfield reproduction using a single loudspeaker array is proposed. The reproduction is based on the derivation of an equivalent global soundfield consisting of a number of individual multizone soundfields. A multizone soundfield reproduction problem is then reduced to the reproduction over the entire region. In the second approach, a spatial region filtering technique is presented to suppress interzone interference in the regions of interests and pass the desired soundfields with no distortion. The third approach involves a design and analysis of a multizone soundfield reproduction system using multiple loudspeaker arrays. The performance of these multizone soundfield reproduction approaches have been verified through numerical simulations. The favorable results indicate that the re-production of multiple independent soundfields in separate zones is possible. In addition, this thesis reveals the fundamental limits on 2D multizone sound field reproduction and shows the extensions of multizone soundfield reproduction in reverberant environment. A car model is also proposed to demonstrate that implementing a simultaneous entertainment system in a car is feasible. Show more