Markovian prediction of sequential temporal patterns in spontaneous speech

Effects of age and dementia on temporal cycles in spontaneous speech fluency

Spontaneous speech of healthy adults consists of alternating periods of fluent and hesitant segments, forming temporal cycles in speech fluency. The regularity of these cycles may be related to the functioning of brain networks during speech planning and execution. This paper investigates the theoretical link between human cognitive functioning and temporal cycles in speech production using a quantitative time series analysis to characterize the regularity and frequency of temporal cycles in adults with differing levels and etiology of cognitive decline. We compare spontaneous speech of adults without a neurological diagnosis, both older and younger, to that of adults with frontotemporal lobar degeneration (FTLD). Two measures of temporal cycle frequency (mean and mode) calculated from the power spectrum of speech fluency represented as a time series were found to be associated with subjects' age, regardless of diagnosis of dementia. Two measures of periodicity (g-statistic and rhythmicity-index), as well as mean frequency, differentiated between adults with and without dementia. Our study confirms the presence of regular temporal cycles in spontaneous speech and suggests that temporal cycle characteristics are affected in different ways by declines in cognitive functioning due to dementia and aging.

Hesitation phenomena: a dynamical perspective

The aim of this paper is to test if hesitation phenomena are periodically distributed in spoken language production. Twenty semi-spontaneous descriptions and narratives produced by five healthy male adults were examined in a multiple case study design. Speech was sampled at a 200 ms rate for time series generation. Fourier analysis indicated that all time series were statistically stationary, which means that speech did not become more or less fluent along each sample. Fourier analysis identified periodic cycles of hesitations in all speech samples. Therefore, hesitations were not randomly distributed in speech production; intervals with more occurrences of hesitations regularly alternated with intervals with fewer occurrences. Thus, hesitations behaved as stable phenomena that could be anticipated. The median and the mean lengths of hesitation cycles were about 9 and 13 s, respectively. It is suggested that macroplanning activities (selecting and ordering information) are language processes compatible with this time scale. Three hesitation cycles were usually identified in each sample, suggesting that spoken language processing occurs in parallel within working memory, with the resources being shared by different processes.

Gender differences in speech temporal patterns detected using lagged co-occurrence text-analysis of personal narratives

This paper describes a novel methodology for the detection of speech patterns. Lagged co-occurrence analysis (LCA) utilizes the likelihood that a target word will be uttered in a certain position after a trigger word. Using this methodology, it is possible to uncover a statistically significant repetitive temporal patterns of word use, compared to a random choice of words. To demonstrate this new tool on autobiographical narratives, 200 subjects related each a 5-min story, and these stories were transcribed and subjected to LCA, using software written by the author. This study focuses on establishing the usefulness of LCA in psychological research by examining its associations with gender. The application of LCA to the corpus of personal narratives revealed significant differences in the temporal patterns of using the word "I" between male and female speakers. This finding is particularly demonstrative of the potential for studying speech temporal patterns using LCA, as men and women tend to utter the pronoun "I" in comparable frequencies. Specifically, LCA of the personal narratives showed that, on average, men tended to have shorter interval between their use of the pronoun, while women speak longer between two subsequent utterances of the pronoun. The results of this study are discussed in light of psycholinguistic factors governing male and female speech communities.

The significance of pauses in spontaneous speech

Studies of filled and silent pauses performed in the last two decades are reviewed in order to determine the significance of pauses for the speaker. Following a brief history, the theoretical implications of pause location are examined and the relevant studies summarized. In addition, the functional significance of pauses is considered in terms of cognitive, affective-state, and social interaction variables.

Prediction of an individual speech pattern from dyadic interaction

One mathematical consequence of a Markov model of conversational rhythm is tested empirically. It is that monologue represents a special case of dialogue in which one participant is silent (or absent). The interaction parameters unique to dialogue indeed contribute little if any information to the prediction of noninteractive speech rhythms. They are nevertheless essential if one wishes to regenerate the dyadic system via the concatenation of monologue sequences.