The study of reverberation, broadly defined as the multipath propagation of sound in an enclosed space, has attracted significant interest from speech processing engineers and researchers alike. This is due in large part to the proliferation of speech processing technologies that facilitate distant talking speech input. In such scenarios, understanding the impact of reverberation on speech quality, and mitigating its detrimental impact through dereverberation techniques, are important and practically well motivated tasks. This research concerns both these topics. More specifically, in this work we (1) extend and develop an objective measure for predicting the level of perceived reverberation, (2) conduct an experimental investigation into reverberation perception and (3) propose the use of a spherical microphone array rake receiver to perform speech dereverberation.

In order to assess the level of perceived reverberation in speech, we develop the extended Reverberation Decay Tail (RDTx) measure. Employing an improved perceptual model, the performance of the measure is first evaluated objectively. Later, we propose experimental methodologies and listening test schemes to collect subjective assessments. From the data obtained, the acoustic parameters most strongly correlated with reverberation perception are identified. The insights gained from the experimental investigation are used to further develop and validate the model of perceived reverberation incorporated in the RDTx measure. The final contribution of this work, is the formulation of acoustic rake receivers in the spherical harmonic domain, which exploit signal reflections to perform speech dereverberation. Evaluating the proposed designs using widely adopted objective metrics, as well as the objective measures developed in this work, demonstrates the constructive use of early reflections can lead to substantial dereverberation.