Joint Blind Enhancement and Passive Source Localisation of Acoustic Signals

This proposal addresses joint tracking and enhancement of signals received from a target which admits an acoustic signature. Processing of real-world analogue signals measured using a variety of sensors, such as microphones, and which propagate in multipath or reverberant environments such as any building, is fundamental to a variety of applications. Within civilian and domestic settings it is important for teleconferencing and hands-free audio enhancement applications. Within the homeland security and defence sectors it is crucial in a wide variety of fields such as forensics and surveillance, and a number of problems requiring target detection and identification -- for example outdoor gunshot detection and localisation in urban environments.Any signal radiated in a confined space exhibits reverberation, also known as multipath propagation, due to reflections off surrounding obstacles. However, many existing signal processing technologies fail to explicitly model the multipath response. Consequently, multipath causes significant problems in signal enhancement and separation, signal detection, high-resolution source localisation, and joint detection, classification, and localisation technologies -- these are all technologies with which consumers are becoming familiar through every day devices such as mobile telephones and audio playback devices.Blind multipath equalisation can be improved with accurate modelling of the acoustic distortion which, in turn, depends on knowledge of the target-position, thereby requiring target tracking. However, many passive target tracking methods -- those which do not actively emit a signature signal, such as active radar and sonar -- suffer from the presence of multipath leading to substantial errors in tracking. Target tracking can thus be improved by modelling the effect of, or even equalising, the acoustic reverberation from the observations, thereby allowing identification of the true source from signal reflections. Target tracking and blind multipath equalisation should therefore be solved jointly rather than separately.The objective of this 12-month research programme is to address the detrimental effect of multipath mitigation by developing algorithms for joint blind enhancement and passive source localisation of speech sources in an indoor multipath environment.