Title:
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Reverberation : models, estimation and application
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The use of reverberation models is required in many applications such as acoustic measurements,speech dereverberation and robust automatic speech recognition. The aim of this thesis is toinvestigate different models and propose a perceptually-relevant reverberation model with suitableparameter estimation techniques for different applications. Reverberation can be modelled in both the time and frequency domain. The model parametersgive direct information of both physical and perceptual characteristics. These characteristicscreate a multidimensional parameter space of reverberation, which can be to a large extent capturedby a time-frequency domain model. In this thesis, the relationship between physical and perceptualmodel parameters will be discussed. In the first application, an intrusive technique is proposed tomeasure the reverberation or reverberance, perception of reverberation and the colouration. Theroom decay rate parameter is of particular interest. In practical applications, a blind estimate of the decay rate of acoustic energy in a roomis required. A statistical model for the distribution of the decay rate of the reverberant signalnamed the eagleMax distribution is proposed. The eagleMax distribution describes the reverberantspeech decay rates as a random variable that is the maximum of the room decay rates and anechoicspeech decay rates. Three methods were developed to estimate the mean room decay rate fromthe eagleMax distributions alone. The estimated room decay rates form a reverberation model thatwill be discussed in the context of room acoustic measurements, speech dereverberation and robustautomatic speech recognition individually.
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