Merle Horne

Word accents and morphology—ERPs of Swedish word processing

Results indicating that high stem tones realizing word accents activate a certain class of suffixes in online processing of Central Swedish are presented. This supports the view that high Swedish word accent tones are induced onto word stems by particular suffixes rather than being associated with words in the mental lexicon. Using event-related potentials, effects of mismatch between word accents and inflectional suffixes were compared with mismatches between stem and suffix in terms of declension class. Declensionally incorrect suffixes yielded an increase in the N400, indicating problems in lexical retrieval, as well as a P600 effect, showing reanalysis. Both declensionally correct and incorrect high tone-inducing (Accent 2) suffixes combined with a mismatching low tone (Accent 1) on the stems produced P600 effects, but did not increase the N400. Suffixes usually co-occurring with Accent 1 did not yield any effects in words realized with the nonmatching Accent 2, suggesting that Accent 1 is a default accent, lacking association with any particular suffix. High tones on Accent 2 words also produced an early anterior positivity, interpreted as a P200 effect reflecting preattentive processing of the tone.

Left-edge boundary tone and main clause verb effects on syntactic processing in embedded clauses - An ERP study

We examined the effects of main clause verb pragmatics and left-edge boundary tones on syntactic processing in Swedish embedded clauses, using listener judgments and Event-Related Potentials. When the syntactic structure did not match the expectation based on the occurrence of a left-edge boundary tone, the acceptance rate decreased significantly, and a biphasic positive effect with an early peak (P345) and a late peak (P600) showed increased processing load. A larger continuous positive effect (P600) was obtained by changing an assertive main clause verb to a nonassertive verb, thereby modifying the lexical pragmatic context of the embedded clause. Increased positivity was also seen at the left-edge boundary tone when it mismatched a preceding nonassertive verb. We conclude that left-edge boundary tones are used in addition to verb pragmatics to guide the syntactic processing of embedded clauses in Swedish, and that pragmatic and prosodic information is integrated immediately.

Cue words and the topic structure of spoken discourse: The case of Swedish men 'but'

The Swedish cue word men ‘but’ can mark the boundary between both different topic units as well as topic-internal units in spontaneous speech. The goal of this study is to see if these two functions of men can be distinguished on the basis of their local prosodic correlates and co-occurring lexical items. Men-tokens in spontaneous narrations were labelled as to their function, first using text-only data. The ‘strong’ tokens (categorized identically by all labellers) were subsequently seen to be clearly differentiated into two classes on the basis of related prosodic parameters and co-occurring lexical items. This distinction was, however, not found for the corresponding ‘weak’ tokens which were subsequently relabelled using both text and speech nor for the data-base as a whole. A test using a neural network trained using strong tokens was seen to be able to correctly categorize 90% of the strong men-tokens as to their associated boundary-type (topic-shift vs. topic-internal). The results show that cue words along with their prosodic correlates and co-occurring lexical items constitute a constellation of important information for understanding how segmentation of spoken discourse is produced and understood.

Empirical evidence for a deletion formulation of the rhythm rule in English

Experimental evidence interpreted within the framework ofprosodic phonology is presented which supports a phonological analysis of the rhythm rule as a pitch-accent-deletion phenomenon such as that advanced by Gussenhoven. The acoustic data from a number of disyllabic words with the stress pattern 2 1 show that within an intonational phrase having a constant register, the height of the fundamental-frequency (F0) peak on the lexically stressed syllable in relation to the following low of the accented syllable was significantly lower in rhythm-rule environments; this can be assumed to be the phonetic correlate of pitch-accent deletion. However, the height of the accent on the initial syllable in relation to the following low of the accented syllable did not increase. The data thus show that it is not motivated to interpret the rhythm rule as a process involving movement of prominence such as that presented in certain metrical analyses, at least as far as production data are concerned. The results suggest, however, that the prominence on the initial syllable is not due just to pitch but rather that the parameters of duration and intensity also play an important role in creating rhythmic alternation, particularly in postfocal position. A proposal for incorporating this finding into the analysis of English rhythm is advanced.

Activating without inhibiting: Left-edge boundary tones and syntactic processing

Right-edge boundary tones have earlier been found to restrict syntactic processing by closing a clause for further integration of incoming words. The role of left-edge intonation, however, has received little attention to date. We show that Swedish left-edge boundary tones selectively facilitate the on-line processing of main clauses, the syntactic structure they are associated with. In spoken Swedish, main clauses are produced with a left-edge boundary tone, which is absent in subordinate clauses. Main and subordinate clauses are further distinguished syntactically by word order when containing sentence adverbs. The effects of tone and word order on the processing of embedded main, subordinate, and neutral clauses (lacking sentence adverbs) were measured using ERPs. A posterior P600 in embedded main clauses and a smaller P600 in subordinate clauses indicated that embedded clauses with sentence adverbs were structurally less expected than neutral clauses and thus were reanalyzed. The tone functioned as a cue for main clause word order, selectively reducing the P600 in embedded main clauses, without affecting the processing of subordinate or neutral clauses. Its perception was reflected in a right frontal P200 effect. The left-edge boundary tone thus seems to activate a main clause structure, albeit without suppressing alternative structures. The P600 was also preceded by a short positive effect in cases where a left-edge boundary tone was absent.

Word-stem tones cue suffixes in the brain.

High and low tones on Swedish word stems are associated with different classes of suffixes. We tested the electrophysiological effects of high and low stem tones as well as tonally cued and uncued suffixes. Two different tasks were used involving either choosing the suffix-dependent meaning of the words, or pressing a button when the word ended. To determine whether effects were in fact due to association of tones with lexical material, delexicalized stimuli were also used. High tones in lexical items produced an increase in the P2 component in both tasks, interpreted as showing passive anticipatory attention allocated to the associated upcoming suffix. This effect was absent for delexicalized forms, where instead an N1 increase was found for high tones, indicating that the high pitch was unexpected in the absence of lexical material, and did not lead to anticipatory attention. A P600 effect was found for uncued high-associated suffixes in the semantic task, which was also where the largest increase was found in reaction times. This suggests that the tonal cues were most important when participants were required to process the meaning of the words.

On the Analysis of Prosody in Interaction

The research reported here is conducted within the ongoing research project “Prosodic Segmentation and Structuring of Dialogue”. The object of study in the project is the prosody of dialogue in a language technology framework. The specific goal of our research is to increase our understanding of how the prosodic aspects of speech are exploited interactively in dialogue—the genuine environment for prosody—and on the basis of this increased knowledge to be able to create a more powerful prosody model. In this paper we give an overview of project design and methods and present some tentative findings.

Pre-Activation Negativity (PrAN) in Brain Potentials to Unfolding Words

We describe an event-related potential (ERP) effect termed the “pre-activation negativity” (PrAN), which is proposed to index the degree of pre-activation of upcoming word-internal morphemes in speech processing. Using lexical competition measures based on word-initial speech fragments (WIFs), as well as statistical analyses of ERP data from three experiments, it is shown that the PrAN is sensitive to lexical competition and that it reflects the degree of predictive certainty: the negativity is larger when there are fewer upcoming lexical competitors.

Predominance of caudate nucleus lesions in acute ischaemic stroke patients with impairment in language and speech

Whereas traditional views of language processing in the brain have assumed that the language function is concentrated to a limited number of cortical areas (Brocas and Wernickes areas), current knowledge points at a much more complex system of language and speech processing involving many brain areas, both cortical and subcortical. The purpose of the current study was to make an unbiased assessment of which cerebral areas are affected in first‐ever acute ischaemic stroke patients identified as having language and speech impairments according to the National Institutes of Health Stroke Scale (NIHSS).

Modelling of Swedish text and discourse intonation in a speech synthesis framework

In this chapter, we present a model for the analysis and synthesis of intonation in spontaneous conversations in Swedish. The model is an enhanced version of the model developed in (1977) and implemented in our text-to-speech synthesis. In our recent work we have developed the model from the perspective of discourse and multi-sentence texts. This takes us out of the restricted one-sentence/utterance analysis and synthesis into the living world of prosody in communication.