Dear Speech Prosody Members,

Our next talk will be October 23:

Lecturer: Sam Tilsen, Department of Linguistics, Cornell University

Title: On the intermittency of speech and the lack of compelling evidence for phrasal rhythm or hierarchical prosodic phrase structure

Oct. 23^rd at 1 pm (Brasilia time = UTC -3)

 You Tube transmission: https://youtube.com/live/nB4fcnTNBC4?feature=share

 Abstract: On the timescale of prosodic phrases, temporal patterns in conversational speech are not very regular. To the contrary, spurts of fluent speech tend to be highly irregular and intermittent. Hesitations and pauses are common. What is the mechanism behind this pattern? In this talk I consider and reject two possible explanations. First, I examine the possibility that a hierarchical organization of relatively long-timescale prosodic units might explain intermittency. Several predictions of hierarchical prosodic structure accounts are examined in an analysis of the Switchboard NXT corpus, but the empirical patterns are not very consistent with those predictions. Moreover, I argue that even laboratory studies that purport to find evidence for hierarchical phrase structure suffer from flawed argumentation. For these reasons, a hierarchical structure-based account of intermittency is suspect. Second, I examine the possibility that there is a phrase-timescale oscillator that governs phrase initiation. I critique recent studies that have argued that such an oscillator is involved in speech production. Through model simulations I show that in order to adequately capture empirical timing patterns, such an oscillator would need an overly powerful ability to change frequency from cycle to cycle. On top of this, the neurophysiological basis for a role of oscillation in governing phrasal timing is called into question. Instead of structural or oscillation-based mechanisms being responsible for phrasal timing, I argue that intermittency arises due to mechanisms responsible for the organization of syntactic and conceptual systems. I present a model in which phrase initiation is contingent on the achievement of a coherent state among those systems, and show how stochastic influences can generate hesitative phenomena that may be the basis for the intermittency of speech.

 Plan:

 1.      Speech activity is intermittent on the timescale of prosodic phrases.

 2.      Hierarchical prosodic phrase structure does not explain intermittency.

 3.      An oscillatory production mechanism does not explain intermittency.

 4.      A model that accounts for intermittency is presented, in which syntactic and conceptual systems must achieve a coherent state before production is initiated.

 5.      Implications of the model are discussed.

 Plinio Barbosa, organizer