Fuzzy neural systems for controlling sound localisation in stereophonic reproduction

The paper presents a new fuzzy logic control (FLC) approach which leads to a stereophonic reproduction controller for localising an auditory image in the desired direction and at the expected distance. Since an auditory event is usually less precisely resolved than the physical sound space, the auditory event need not coincide with a physical sound source, and can occur at a position where nothing is visible to a listener. It turns out that controlling the auditory image is more difficult than the localisation of a sound image. Unlike the conventional sound image localisation approach, our fuzzy logic controller can take account of knowledge in human auditory perception. The ambiguous human auditory perception in conjunction with the spatial reverberation from the surrounding environment can be represented by a number of fuzzy-set values. From these fuzzy representations, the auditory image localisation controller characterises the function of how control outputs depend on control inputs as fuzzy implications or associations. Furthermore, the overall stereophonic reproduction controller can be realised by a 45-rule fuzzy associative memory (FAM) system. The performance of FLC-based auditory image localisation is verified in a number of experiments.