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

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

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

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

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.

Example (from Prevost)

Example (from Calhoun et al.)

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”

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

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? (*)

Finding contrastive focus

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

Example Output

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?