Recovering parentheses from spoken algebraic expressions

A study of the relationship between the syntactic and prosodic organization of spoken algebraic expressions is reported. It was found that subjects were very consistent in their placement of junctures when reading algebraic expressions slowly. Furthermore, there was an almost perfect correlation between measured silence and perceived juncture. Rules were developed for inserting parentheses based on the location and measured duration of silence intervals in an utterance. Listeners were asked to insert parentheses, given the spoken form, and the consistency of their answers was measured by a chi-square test. For those cases where there was listener agreement on a single answer, the rules were tested and found to agree with the listeners from 91 to 95 percent of the time. Mathematically experienced and mathematically naive listeners displayed similar performance that suggests that the acoustic cues used by the speaker to indicate syntactic structure in this restricted domain of discourse may have a more general applicability.