1. Information Structure and Prosody
LING 575
Ruth Morrison
Information Structure and Prosody

2. Papers Prevost, 1996 Calhoun et al., 2005 Hirschberg, 1990
Context-sensitive prosody in text generation using information structure
Calhoun et al., 2005
Human annotation of information structure
Hirschberg, 1990
Improving prosody in TTS using a variety of features

3. Information Structure: Newness
New information:
Discourse elements introduced during the utterance that cannot be inferred
Mediated Information:
Discourse elements that were not mentioned previously but can be inferred
Old Information:
Previously mentioned discourse elements

4. Information Structure: Theme and Rheme
The part of the utterance which contains previous information and ties the utterance to previous discourse
Rheme
The part of the utterance which contributes new information

5. Information Structure: Contrastive Focus or Kontrast
Special focus placed on elements to contrast them with others in the previous or current phrase
Occurs within theme and rheme
Some disagreement about terminology and theory, according to Calhoun et al.

6. Example (from Prevost)

7. Example (from Calhoun et al.)

8. Some previously-used indicators of prosody (Hirschberg)
“Accent is predictable (if you're a mind-reader)” (Bolinger, 1972), “mind-reading attempts continue”
Newness (“attentional state”)
Open versus closed class words
Cue phrases (“now”, “well”, “by the way”)
Syntactic information
Lexical stresses of compounds
“Discourse-based indicators of contrastiveness”

9. Prevost (1996): Overview
System for describing items from a knowledge base with generated spoken language
Need to incorporate information from theme/rheme and contrastive focus to generate adequate prosody

10. Theme/Rheme and Intonation
Theme and rheme have prototypical tunes
Theme: L+H* LH%
Rheme: H* LL%
Good enough for simple declarative sentences
But where is the pitch accent? (*)

11. Finding contrastive focus

12. Generation
Uses information about previous discourse context, previously given information
Three phases: content generation, sentence planning, sentence realization
Determines theme and rheme (in content generation), contrastive focus (in sentence planning)
Surface form of sentence is computed from semantic form

13. Example Output

14. Criticisms/Discussion
More applicable to more complex information state dialogs with limited domains than general TTS as in Hirschberg
Theory seems solid, but no quantitative evaluation shown
Is more human-like prosody really extrinsically better?