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This thesis addresses the intelligibility enhancement of speech that is heard within an acoustically noisy environment. In particular, a realistic target situation of a police vehicle interior, with speech generated from a CELP (codebook-excited linear prediction) speech compression-based communication system, is adopted. The research has centred on the role of the CELP speech compression algorithm, and its transmission parameters. In particular, novel methods of LSP-based (line spectral pair) speech analysis and speech modification are developed and described. CELP parameters have been utilised in the analysis and processing stages of a speech intelligibility enhancement system to minimise additional computational complexity over existing CELP coder requirements. Details are given of the CELP analysis process and its effects on speech, the development of speech analysis and alteration algorithms coexisting with a CELP system, their effects and performance. Both objective and subjective tests have been used to characterize the effectiveness of the analysis and processing methods. Subjective testing of a complete simulation enhancement system indicates its effectiveness under the tested conditions, and is extrapolated to predict real-life performance. The developed system presents a novel integrated solution to the intelligibility enhancement of speech, and can provide a doubling, on average, of intelligibility under the tested conditions of very low intelligibility.

Social theorists have advanced a number of analyses of the social significance of the position and role of the engineer as mediator of relations between technology and society. Some approaches have stressed the technological determinants of the occupational organisation and social consciousness that defines and guides the engineer in the execution of their professional expertise, and others the influence of prior economic determinants. Implicit in these approaches is the view that questions about the social position and significance of the role of the engineer involve a consideration of their position in the wider system of social stratification. This thesis examines the position and role of the industrial engineer in the context of recent theoretical debates on the identification and character of the new middle class, and examines the utility of class analyses in understanding the organisation and consciousness of British engineers. Part I outlines some of the more salient themes in the analysis of the role of the engineer, and examines the theoretical debate on the formal conceptualisation of the new middle class and the character of organisation and consciousness within it. This forms the basis for the analysis of the organisation and consciousness of British engineers undertaken in Part II. This latter section of the thesis presents an examination of contemporary developments in the occupational organisation of British engineers and reports new findings from a study of the social consciousness of industrial engineers. The major conclusion of the study is that the peculiarities of the position and role of British engineers are best explained by conceptual models which are able to highlight the influence of sociocultural variables in the definition of the occupational roles which form the basis for occupational organisation and social consciousness. Of particular importance in the case of the British engineer is the low cultural value placed upon engineering expertise which is reflected in the narrow definition of the occupation's role, their weak occupational organisation and self-consciousness, and, ultimately their ill-defined position in the system of social stratification.