Summary and overview of my PhD thesis taken from its introductory chapter:
The contribution of intonation to the perception of foreign accent
While it is generally acknowledged that prosody and especially intonation contribute to the impression of foreign accent, the number of studies and analyses explicitly dealing with the description of prosodic/intonational foreign accent is rather small, particularly in the context of models of second language acquisition.
Contrastive studies of intonation in two or more languages (for example Grabe's comparison of aspects of German and British English intonation) are however relatively frequent and do give strong indications of possible causes and manifestations of intonational foreign accent that are likely to occur, if native speakers of one of the contrasted languages were to speak the respective other language. Apart from these comparative studies of intonation there are only few studies directly combining the areas of prosody, particularly intonation, and foreign accent.
A notable exception is the 1983 dissertation "English intonation from a Dutch point of view" by Nico Willems which examines intonational deviations in the English productions of native speakers of Dutch, draws up a corresponding inventory and confirms the deviations' relevance in perceptual experiments using resynthesis. The main aim of Willems's study is to give an exact phonetic description of these relevant deviations and to use it in the creation of an effective course of (British) English intonation for native speakers of Dutch. Willems neither specifically relates his findings to an encompassing linguistic framework, nor does he analyze them within the context of second language acquisition.
Segmental aspects of foreign accent, on the other hand, have been described in detail in their various forms. Accordingly, the existing models of second language acquisition have been developed on the basis of the segmental aspects of acquisition and foreign accent. For the reasons stated above it can thus be claimed to be the overall motivation of this study to give a detailed, coherent account of intonational foreign accent (in the comparison of two specific languages) and to attempt to connect this description to the established theories of second language acquisition. In more concrete terms the major objectives of this study can be summarized as follows.
To ensure a scientifically exact identification of intonational foreign accent the use of speech technology is advantageous. In an analysis-by-synthesis procedure a foreign-accented utterance will be compared with utterances differing in only one particular tonal aspect. The respective judgments regarding the perception of foreign accent will determine if the detected and subsequently altered tonal characteristics are indeed instances of intonational foreign accent. This is also the main reason why American English and German were chosen for this analysis. For both languages the necessary intonation description and possibilty of F0 generation are available. While the aspect just described controls to a large extent how the analysis is performed, the second objective of the study must define the conditions under which a meaningful analysis of intonation and intonational foreign accent is possible. This concerns especially the recognition of the fact that the form of the detected intonational deviations, i.e. instances of intonational foreign accent depends on the chosen model of intonation description. In addition to this, elaborate assumptions about the role of context and variation in intonation must also be taken into consideration in the identification of intonational deviations. On the basis of these prerequisites the third objective of the study can address the actual identification of concrete manifestations of intonational foreign accent in the German productions of native speakers of American English, and vice versa in the American English productions of native speakers of German, as well as the subsequent systematic classification of major types of intonational foreign accent. Finally, the study aims to investigate the contribution of prosody and intonation in particular to the general perception of foreign accent, also determining the shares of intonation and the remaining aspects of prosody in relation to each other and comparing both with the contribution of segmental aspects.