Intonation of Thai learners of English for marking narrow focus

Abstract

Languages differ in the ways they mark the focus of information. While English marks focus by means of pitch accent placement and relative acoustic prominence in elements such as f0, intensity and duration, marking focus in Thai can be accomplished by either using a particular word order, changing lexical items or syntactic constructions, using prosody such as extra high tones and phrase-final lengthening to emphasise information, emotions and attitudes, or using combinations of these. In the current study, using prosodic means to express the focus is of special interest. Basically, the prosodic patterns of the two languages involve the use of categorical means such as accent types and gradient means, such as f0, duration and loudness to variable degrees, as well as alignment and scaling. This study thus investigates if there are any differences between Thai learners and native speakers of English in the use of accent choices and the acoustic-phonetic characteristics of focus, in particular via using rising accents. This study presents the first detailed description covering both phonological and acoustic phonetic analyses of the prosodic marking of focus in English produced by Thai learners. The aims of this study are threefold: 1) to investigate to what extent Thai learners and native speakers of English mark narrow informative focus prosodically, in particular in terms of the use of accent types and other strategies such as deaccenting; 2) to describe Thai learners’ and native English speakers’ acoustic cues for marking this kind of focus, as well as tonal alignment and scaling of rising accents associated with marking focus in question; 3) to explore the factors which affect differences in the realisations of focus between Thai learners and native speakers of English, such as L2 English proficiency levels, focus positions, and learners’ gender. The study concentrates on a production experiment conducted on the basis of the Autosegmental-Metrical approach to intonational phonology. Twenty native English speakers and 20 native Thai speakers produced English speech data during question-and-answer tasks recorded in laboratory conditions. Transcriptions of the speech data were based on the Tones and Break Indicessystem with the help ofspeech software, Praat. The results showed that native English speakers and Thai learners predominantly used rising accents (L*+H, L+H*, L+<H*) to mark narrow informative focus and they also relied on other different prosodic strategies such as deaccenting and rephrasing. H* can be found in both groups, but L* in Thai group only. Using a high (H*) accent and a rising (L+H*) accent with or without a later peak reflects Thai learners’ shared characteristics of how to mark focus using pitch prominence to highlight information. In this case, CAH may be applied for prediction in that shared categories of accents are easy to produce and ready to use. The use of an accent alongside prosodic strategies such as compressed pitch range and rephrasing can be considered to be due to either non-shared characteristics or the development of a system concerning the characteristics of the L2 intonation patterns produced by Thai learners in expressing the focus. In this case, if CAH was applied, the deaccentuation which is used by native English speakers will be difficult to produce and Thai learners would transfer strategies such as L1 compressed pitch range and rephrasing into L2 English. In addition, they differed in terms of using acoustic cues, as well as tonal alignment and the scaling of rising accents which they used to mark focus. The analysis of Thai learners’ acoustic phonetic data showed that they tended to employ higher pitch, longer duration and greater intensity and they used rising accents with a delayed peak (L+<H*) resulting in greater pitch slope/size, especially in sentence-initial positions. Factors such as L2 English proficiency level, position of focus, as well as gender still play roles in causing differences such as the misalignment of tonal targets which, it can be speculated, could be a result of the development and use of L2 intonation; whereas an increase in degrees of f0 and duration can be attributed to L1 influence. If Ladd’s (1996, 2008) taxonomy of cross-linguistic differences in intonation and Mennen’s (2015) L2 intonational learning theory (LILt) are taken into account, this study gives evidence for systematic differences and realisational differences between L1 English and L2 English; that is, in using categorical and gradient prosodic strategies in the expression of focus. Finally, one of the findings has pedagogical implications concerning the use of focus-marking strategies. Therefore, apart from learning where and how native English speakers make words prominent, Thai learners should also learn how native English speakers deaccent out-of-focus material or information. This is because deaccenting mostly co-occurs with an accent placement in the marking of focus in the native English speakers’ data. This study makes contributions to L2 research into intonation and the marking of focus, in particular to Mennen’s (2015) L2 intonational learning theory (LILt). It also makes contributions concerning the concepts used to explain tonal alignment and scaling within Ladd’s (2008) AM theory by offering empirical evidence supporting an understanding of these tonal phenomena in Thai learners compared to native speakers of English.