Surround sound can be delivered to consumers more efficiently

Recent research conducted by scientists at the University of Surrey in collaboration with Bang & Olufsen and the BBC, shows that surround sound can be delivered to the consumer more efficiently by taking into account the results of perceptual tests. Although improvements in the audio quality of consumer entertainment systems such as DVDs, CDs, digital TV, home cinema and computer games are technically possible, they may no longer be necessary. In fact, the intelligent limiting of sound quality, based on the results of perceptual tests using real programme material, could enable media companies to use network capacity to increase the number and types of services available, while still delivering good surround sound quality.

The research also revealed that if visual and audio images are presented simultaneously, such as when watching TV and films or playing computer games, subjects’ perception of sound quality was altered.

Describing the outcomes of the project, Dr Francis Rumsey, the project leader, said “we were surprised to find just how much we could reduce the sound quality of some of the channels in a typical five channel home cinema system without our listening subjects reporting a large change in overall quality. These were expert listeners, highly trained as sound engineers, so they would have noticed if there were major changes. Although we can’t claim that all material can be delivered with these sorts of compromises, there is certainly a lot of typical music and audio-visual material that could be treated in this way. We have developed a prototype expert system that can be used to predict the resulting quality when certain changes are made to the sound quality of specific audio channel. This could be used by broadcasters and other media delivery organisations or equipment manufacturers to optimise the use of their networks. It means that they can still deliver good quality surround sound to their audiences without necessarily taking up as much bandwidth as would be needed normally. Our results could be used in conjunction with existing technology that is used to squeeze high quality audio into a small space, such as MPEG and Dolby Digital coders.”