The team has also worked on implementation and analysis of sound zone algorithms from the literature, with the aim of optimising performance and robustness.Initially, these have been evaluated using a range of physical performance metrics, and have systematically examined optimisation methods such as contrast optimisation and least-squares optimisation, which had not previously been compared in the literature.This project is unique in the way that it combines engineering (to create the sound zones) and psychoacoustics (to evaluate and predict the perceived quality).
This was integrated into a novel 'planarity control' cost function, that achieved high contrast between the zones whilst also reducing troublesome interference patterns from the target zone .
The planarity control can also be used to create multiple virtual loudspeakers with differing positions, allowing the creation of 2-channel stereo or multichannel reproduction in each sound zone .
In other words, reproducing sound in specific zones whilst minimising spill into other zones.
An example is shown below of a living room containing two sound zones, A and B, with the remaining space being either a quiet area, or an area where the reproduced sound is relatively unimportant.
The engineering research is being conducted by staff and students from the Centre for Vision, Speech and Signal Processing, in collaboration with engineers from Bang and Olufsen.