Prosody in Production

Prosodic Structure

Prosody includes acoustic information associated with rhythm, intonation, pausing, and accents (emphasis). Prosodic information is typically conveyed through changes in fundamental frequency (f0), which correlates with the perception of pitch, and changes in intensity, which correlates with the perception of loudness. It is also linked to pausing and the lengthening and reduction of individual words.

Prosody can vary between otherwise identical utterances in ways that influence the interpretation of a sentence. For example, consider (1), where capitalization indicates an accent and “//” indicates a break in the speech stream.

• (1a)
  Ketchup is a vegetable.
• (1b)
  Ketchup is a vegetable?
• (1c)
  KETCHUP is a vegetable.
• (1d)
  Ketchup is a VEGETABLE.
• (1e)
  The cop saw // the spy with the telescope.
• (1f)
  The cop saw the spy // with the telescope.

The sentence in (1a) will sound like an assertion if it is produced with a fall in f0 across the sentence, but it will sound like a question if it is produced with a rise (1b). These two productions convey different speaker attitudes about the truth of the utterance. In (1c), accenting ketchup conveys that it and not, say, mustard is a vegetable. Similarly, (1d) implies that ketchup is a vegetable and not a fruit. Breaks in the speech stream, which are also called prosodic boundaries, can be signaled by a pause, a change in f0, or lengthening of the preboundary word. A prosodic boundary after the verb saw in (1e) biases the listener toward an interpretation in which the spy has a telescope whereas a break after spy biases the listener toward an interpretation in which the cop has the telescope. These examples illustrate that prosody can influence the interpretation of an utterance even if the words in the utterance do not vary.

Prosodic features such as prosodic boundaries, accents, rhythm, and pitch contours are represented at an abstract phonological level of representation called prosodic structure. There is a great deal of controversy over the nature of this representation. There is disagreement over whether there are [Page 621]different types of prosodic phrases and how they might differ, whether and how these phrases are represented hierarchically, whether accents differ in form and meaning, how intonational contours are structured, and the nature of the interface between prosodic structure and other aspects of language.

Production

Traditionally, it has been assumed that the role of prosody is to convey pragmatic, discourse, and syntactic information to listeners. However, a growing body of evidence suggests that there might also be a link between speaker internal production processes and prosody: Speakers are more likely to produce prosodic boundaries and accents at points of production difficulty.

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