This paper proposes a suitable method for simulating impulses with appropriate amplitude, spectral, and inter-arrival characteristics. The statistics used to develop the parameters of this model are based on statistics derived from observations of impulse noise on the telephone networks of British Telecom (BT) and Deutsche Telekom (DT). This paper initially reviews the former DT approach to impulse noise generation for testing digital subscriber line systems, so called xDSL systems. Some problems are highlighted and an alternative technique is suggested that is capable of generating impulses with both appropriate amplitude an spectral characteristics.

In this paper, we describe a new pervasive conversational system that provides access to multiple desktop applications, from multiple client devices, using multiple input modalities. Client devices currently supported include desktop and telephone, and the applications incorporated include email, calendarand address book. When the access is from a desktop, both conversational natural language and graphical inputs are supported. The paper describes the overall architecture to support such a pervasive conversational system, along with innovations in continuous speech recognition, statistical natural language understanding, and dialog management that were developed to build the system. The paper also describes the partially unsupervised Wizard-of-Oz style setup to collect real-use data, and the performance of the statistical models constructed using this data for speech recognition and natural language understanding.

This paper addresses suggestions in the literature that the generation of speech is a nonlinear process. This has sparked great interest in the area of nonlinear analysis of speech with a number of studies being conducted to investigate whether low dimensional chaotic attractors exist for speech. This paper examines a corpus of sustained vowel sounds which were recorded for this study to ensure dynamical invariance. The sounds are assessed by a range of the invariant geometric features developed for the analysis of chaotic systems such as correlation dimension, Lyapunov exponents, and short-term predictability. The results presented suggest that although voiced speech is well characterized by a small number of dimensions, it is not necessarily chaotic. Finally, a synthesis technique for voiced sounds is developed inspired by the technique for estimating the Lyapunov exponents.