Blocking of alveolar flapping in speech production: the role of syntactic boundaries and deletion sites

Abstract

Experiments were conducted to examine the influence of syntactic boundaries on the operation of a phonological rule in speech production. Groups of ten or more speakers read sentences in which the phonological rule of Alveolar Flapping could be optionally applied across a word boundary. Experiment 1 showed that the occurrence of Flapping is blocked by major syntactic boundaries and that this blocking is not attributable to pausing. Experiment 2 demonstrated that the occurrence of Flapping is markedly reduced when the key word boundary coincides with an embedded clause boundary but is unaffected by boundaries of other phrase types, including noun phrases and verb phrases. Traditional theories of boundary strength, which assign equal weight to boundaries associated with different types of constituents, fail to account for these results. Finally, Experiment 3 showed that Flapping is also reduced in the environment of a syntactic deletion site.The results of these experiments indicate that traditional metrics of boundary strength, as well as linguistic formulations of phonological rules, must be elaborated to recognize the special status of clause boundaries and deletion sites. In speech processing, blocking appears to reflect a constraint on the speaker’s ability to look ahead to consider phonetic information in the word-initial segment following the key word boundary. This information is required to satisfy the conditions under which the phonological rule can apply. The look-ahead capability of the speaker may be limited at word boundaries that coincide with clause boundaries and deletion sites because of the speaker’s need to devote immediate processing capacity to the programming of other prosodic attributes typically accompanying these locations.