Johan Frid

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.

Development of speech motor control: Lip movement variability

This study examined variability of lip movements across repetitions of the same utterance as a function of age in Swedish speakers. The specific purpose was to extend earlier findings by examining variability in both phase and amplitude. Subjects were 50 typically developed native Swedish children and adults (28 females, 22 males, aged 5 to 31 yr). Lip movements were recorded during 15 to 20 repetitions of a short Swedish phrase using three-dimensional articulography. After correction for head movements, the kinematic records were expressed in a maxilla-based coordinate system. Movement onset and offset of the utterance were identified using kinematic landmarks. The Euclidean distance between receivers on the upper and lower lips was calculated and subjected to functional data analysis to assess both phase and amplitude variability. Results show a decrease in both indices as a function of age, with a greater reduction of amplitude variability. There was no difference between males and females for either index. The two indices were moderately correlated with each other, suggesting that they capture different aspects of speech production. Utterance duration also decreased with age, but variability was unrelated to duration. The standard deviation of utterance duration also decreased with age. The present results thus suggest that age related changes in speech motor control continue up until 30 years of age.

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.

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.

Developing the modelling of Swedish prosody in spontaneous dialogue

The main goal of our current research is the development of the Swedish prosody model. In our analysis of discourse and dialogue intonation, we are exploiting model-based resynthesis. By comparing synthesized default and fine-tuned pitch contours for the dialogues under study, we are able to isolate relevant intonation patterns. This analysis of intonation is related to an independent modelling of topic structure consisting of lexical-semantic analysis and text segmentation. Some results from our model-based acoustic analysis are presented, and its implementation in text-to-speech-synthesis is discussed.

Forehearing words: Pre-activation of word endings at word onset

Occurring at rates up to 6-7 syllables per second, speech perception and understanding involves rapid identification of speech sounds and pre-activation of morphemes and words. Using event-related potentials (ERPs) and functional magnetic resonance imaging (fMRI), we investigated the time-course and neural sources of pre-activation of word endings as participants heard the beginning of unfolding words. ERPs showed a pre-activation negativity (PrAN) for word beginnings (first two segmental phonemes) with few possible completions. PrAN increased gradually as the number of possible completions of word onsets decreased and the lexical frequency of the completions increased. The early brain potential effect for few possible word completions was associated with a blood-oxygen-level-dependent (BOLD) contrast increase in Brocas area (pars opercularis of the left inferior frontal gyrus) and angular gyrus of the left parietal lobe. We suggest early involvement of the left prefrontal cortex in inhibiting irrelevant left parietal activation during lexical selection. The results further our understanding of the importance of Brocas area in rapid online pre-activation of words.

Revisiting Southern and Central Swedish intonation from a comparative and functional perspective

Revisiting South and Central Swedish intonation from a comparative and functional perspective