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<Paper uid="P96-1038">
  <Title>A Prosodic Analysis of Discourse Segments in Direction- Giving Monologues</Title>
  <Section position="3" start_page="0" end_page="0" type="intro">
    <SectionTitle>
2 Theoretical and Empirical
Foundations
</SectionTitle>
    <Paragraph position="0"> It has long been assumed in computational linguistics that discourse structure plays an important role in Natural Language Understanding tasks such as identifying speaker intentions and resolving anaphoric reference. Previous research has found *The second author was partially supported by NSF Grants No. IRI-90-09018, No. IRI-93-08173, and No.</Paragraph>
    <Paragraph position="1"> CDA-94-01024 at Harvard University and by AT&amp;T Bell Laboratories.</Paragraph>
    <Paragraph position="2"> that discourse structural information can be inferred from orthographic cues in text, such as paragraphing and punctuation; from linguistic cues in text or speech, such as cue PHI~.ASES 1 (Cohen, 1984; Reichman, 1985; Grosz and Sidner, 1986; Passonneau and Litman, 1993; Passonneau and Litman, to appear) and other lexical cues (Hinkelman and Allen, 1989); from variation in referring expressions (Linde, 1979; Levy, 1984; Grosz and Sidner, 1986; Webber, 1988; Song and Cohen, 1991; Passonneau and Litman, 1993), tense, and aspect (Schubert and Hwang, 1990; Song and Cohen, 1991); from knowledge of the domain, especially for task-oriented discourses (Grosz, 1978); and from speaker intentions (Carberry, 1990; Litman and Hirschberg, 1990; Lochbaum, 1994). Recent methods for automatic recognition of discourse structure from text have incorporated thesaurus-based and other information retrieval techniques to identify changes in topic (Morris and Hirst, 1991; Yarowsky, 1991; Iwafiska et al., 1991; Hearst, 1994; Reynar, 1994).</Paragraph>
    <Paragraph position="3"> Parallel investigations on prosodic/acoustic cues to discourse structure have investigated the contributions of features such as pitch range, pausal duration, amplitude, speaking rate, and intonational contour to signaling topic change. Variation in pitch range has often been seen as conveying 'topic structure' in discourse. Brown et al. (1980) found that subjects typically started new topics relatively high in their pitch range and finished topics by compressing their range. Silverman (1987) found that manipulation of pitch range alone, or in conjunction with pausal duration between utterances, facilitated the disambiguation of ambiguous topic structures. Avesani and Vayra (1988) also found variation in pitch range in professional recordings which appeared to correlate with topic structure, and Ayers (1992) found that pitch range correlates with hierarchical topic structure more closely in read than spontaneous conversational speech. Duration of pause between utterances or phrases has also been identi-</Paragraph>
  </Section>
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