Since Chomsky & Halle (1968), English stress preservation – oríginal -> orìginálity, óbvious -> óbviousness – has been important in generative discussions of morphophonological interaction. This thesis carries out empirical investigations into English stress preservation, and uses their results to argue for a particular version of Optimality Theory: Stratal Optimality Theory (‘Stratal OT’) (Kiparsky, 1998a, 2000, 2003a; Bermúdez-Otero, 1999, 2003, in preparation). In particular, the version of Stratal OT proposed in Bermúdez-Otero (in preparation) and Bermúdez-Otero and McMahon (2006) is supported. The empirical investigations focus upon the type of preservation where preserved stress is subordinated in the preserving word (‘weak preservation’): e.g. oríginal -> orìginálity; àntícipate -> antìcipátion. Evidence for the existence of weak preservation is presented. However, it is also shown that weak preservation is not consistently successful, but that it is, rather, probabilistically dependent upon word frequency. This result is expected in light of work like Hay (2003), where it is proposed that word frequency affects the strength of relationships between words: stress preservation is an indicator of such a relationship. Stratal OT can handle the existence of English stress preservation: by incorporating the cyclic interaction between morphological and phonological modules proposed in Lexical Phonology and Morphology (‘LPM’), Stratal OT has the intrinsic serialism which is necessary to predict a phenomenon like English stress preservation. It is shown that the same cannot be said for those of models of OT which attempt to handle preservation while avoiding such serialism, notably, Benua (1997). Bermúdez-Otero’s (in preparation) proposal of ‘fake cyclicity’ for the first stratum in Stratal OT can capture weak preservation’s probabilistic dependence upon word frequency. Fake cyclicity rejects the cycle which has previously been proposed to handle weak stress preservation, in LPM and elsewhere; instead, fake cyclicity proposes that weak preservation is a result of blocking among stored lexical entries. Blocking is independently established as a psycholinguistic phenomenon that is probabilistically dependent upon word frequency; in contrast, the cycle is not a probabilistic mechanism, and so can only handle instances of stress preservation failure by stipulation.

The present study aims to investigate how the acoustic cues (i.e., mean pitch, duration, and mean intensity) are utilized by Taiwanese EFL learners to produce English noun-verb stress contrasts in falling and rising intonation. In addition, we examine how English native speakers perceive the English noun-verb stress contrasts produced by Taiwanese EFL learners. To examine English noun-verb stress contrasts in falling intonation, eight Taiwanese EFL learners, either in advanced level or intermediate level, recorded six English noun-verb stress contrasts which were put in a sentence frame (i.e., No, it is ______.), and four native speakers of English were also recruited for recording as a basis for comparison. Then, the vowels of the stressed and unstressed syllables were measured in terms of mean pitch, duration, and mean intensity. The results suggest that Taiwanese EFL learners in advanced or intermediate level produce English noun-verb stress contrasts by utilizing mean pitch, duration, and mean intensity, but the extent they utilize mean pitch is different from English native speakers. That is, they produced stressed syllables that are less high-pitched than English native speakers. To investigate how Taiwanese EFL learners utilize the correlates to produce the English noun-verb stress contrasts in rising intonation, the same groups of speakers also recorded the six English noun-verb stress contrasts put in another sentence frame (i.e., Did you say ______?), and the vowels of the stressed and unstressed syllables were measured and analyzed. The results show that Taiwanese EFL learners, either in advanced or intermediate level, utilize duration, but not mean pitch, to produce the noun-verb contrasts, while English native speakers use both duration and mean pitch. To examine how English native speakers perceive the English noun-verb stress contrasts with Taiwanese-accent, another eight English native speakers participated in doing several tasks including identification tasks, accent-rating tasks, and comprehensibility tasks. The results suggest that although Taiwanese EFL learners¡¦ production of the six English noun-verb stress contrasts in falling intonation was rated as foreign-accented, our eight English native speakers can identify their production with higher accuracy. In contrast, production in rising intonation was also rated as foreign-accented; however our English native speakers have difficulties in identifying their production.

It is well-known that the early assignment of prominence in sequences like THIRteen MEN vs. thirTEEN, (defined as the Rhythm Rule, or post-lexical stress shift), is an optional phenomenon. This dissertation examines some of the factors that encourage the application of stress shift in English and how it is phonetically realised. The aim is to answer two sets of questions related to why and how stress shift occurs in English: 1a) Does prosodic boundary strength influence stress shift? 1b) Does the adjacency of prominences above the level of the segmental string encourage stress shift? 2) How is stress shift realized? a) Is stress shift only a perceptual phenomenon? and b) Which syllables, if any, change acoustically when stress shift is perceived? To answer these questions, four experiments were designed. The first three experiments test whether the strength of the prosodic boundaries before and after the target word (e.g., canteen) influence stress shift. The effect of the strength of the left-edge prosodic boundary was investigated by comparing perceived stress patterns of the target (e.g., canteen) as produced in isolation where it is preceded by an utterance- and a phrase- initial prosodic boundary (the Isolated condition) with its rendition when embedded in a frame sentence (e.g., Say canteen again) where the left prosodic boundary before canteen is weaker (the Embedded condition). Results show a very clear tendency towards late phrasal prominence on the final accentable syllable (e.g., -teen in canteen) in the Embedded condition while in the Isolated condition this pattern appeared in less than half of the targets, showing that the stronger left boundary increased the incidence of stress shift. Two more experiments manipulated the strength of the boundary to the right of the target (#) respectively by changing the syntactic parse of the critical phrase (e.g. canteen cook) in sequences like (1) and by manipulating constituent length as in (2). Results showed that the syntactic manipulation significantly affected the strength of the prosodic boundary between the clashing words which was stronger in (1b) relative to (1a), and affected the incidence of stress shift, which was higher in (1a) relative to (1b). The length manipulation also affected the rate of stress shift, which was significantly higher in the phrase with the shorter word, e.g., soups (2a) relative to phrase with the longer word, e.g., supervisors (2b). (1) Example from the Syntax Experiment a. Who is the canteen (#) cook these days? (Pre-modifier + Noun) b. How do the canteen (#) cook these days? (NP + VP) (2) Example from the Length Experiment a. It should include the canteen (#) soups again. (Shorter constituent) b. It should include the canteen (#) supervisors again. (Longer constituent) Whilst we knew from the literature that the grouping of the clashing words within one Intonational Phrase (IP) encourages stress shift, results from the Syntax and Length experiments indicate that this (i.e., the phrasing of the clashing words within same IP) is not sufficient condition for the occurrence of stress shift, and that fine-grained degrees of boundary strength below the Intonational Phrase can drive changes in prominence pattern. The fact that higher rates of stress shift (and associated significant acoustic changes) were driven by manipulations of constituent length --for sequences with the same syntactic structure-- provides support for the idea that prosodic (rather than syntactic) boundaries directly influence stress shift. The fourth experiment tests the definition of stress clash in English in cases like fourteen candles where the two main lexical prominences are strictly adjacent along the time dimension, in fourteen canoes where the prominences are not adjacent in time, but adjacent at the higher levels of the metrical hierarchy, and in fourteen canteens where the main lexical prominences are not adjacent, and do not clash. This experiment highlighted and resolved an unacknowledged disagreement about what clash status sequences with one weak intervening syllable (e.g., fourTEEN caNOES). The fourTEEN caNOES type were shown to behave like metrically clashing sequences (e.g., fourteen CANdles) in attracting stress shift, and differently from the non-metrically-clashing sequences (e.g., fourteen CANTEENS) in discouraging it. These results provide empirical support for the Standard Metrical Theory (e.g. Selkirk, 1984; Nespor & Vogel, 1989) claim that 1) stress clash matters in triggering stress shift and that 2) stress clash in English is defined at the higher prosodic levels and not restricted to the level of the segmental string as indirectly assumed in a growing body of research (e.g., Vogel, Bunnel & Hoskins, 1995; Tomlinson, Liu & Fox Tree, 2014). Along with the establishment of prosodic boundary strength as one of the predictors influencing stress shift, another important contribution of the thesis is providing empirical evidence that the English Rhythm Rule is not solely a perceptual phenomenon and that it is associated with acoustic correlates. The main correlates of perceived stress shift consistently appearing across experiments is the decrease in the duration of the main lexical prominence of the target (e.g., -teen in canteen) and the increase of fundamental frequency and Sound Pressure Level peaks and on the initial syllable (e.g., canin canteen), when followed by a main clashing phrasal prominence. The acoustic analysis shows that the first accentable syllable also contributes in the perception of stress shift. This latter result does not lend support to the deletion formulation of the Rhythm Rule (Gussenhoven, 1991) which stipulates that the impressions of stress shift are solely associated with changes of prominence in the last accentable syllable of the target (e.g. -teen in canteen). Along with the determination of the acoustic correlates of perceived stress shift in English, the present research 1) indicates that fine-grained gradations of prosodic boundary strength can influence stress shift, 2) shows that while stress clash can increase the incidence of stress shift, stress shift can take place even in environments completely free of stress clash, and 3) provides evidence that stress clash should not be construed simply as the concatenation of two main lexical prominences along the time dimension.