? Two years of support are requested for an investigation of the acoustic properties of speech used by an infant listener to discover the syntactic constituents of his/her language. ? ? Infants' use of speech cues for some tasks in language acquisition, for example word segmentation, has been extensively discussed in the literature. However, the use of cues in the acquisition of other units of the grammar such as the clause or phrase, has not been as extensively explored. Nonetheless, there is some evidence indicating that infants are sensitive to the strength of prosodic cues in segmentation of these larger units. For example, it has been shown that infants segment speech more easily when speech is infant-directed and hence is speech that is subject to larger pitch excursions and greater preboundary lengthening. ? ? This project has two objectives: (1) to uncover the prosodic cues infants are most sensitive to in continuous speech. (2) To find out which of these cues is most heavily weighted in infants' parsing of the speech stream into large grammatical units such as the clause. The use of cues to segment larger units (clauses and phrases) is particularly important since these units are segmented at a younger age than smaller units, such as the word. The prosodic properties of clauses are larger and more language general than smaller units, thus, they may lay the groundwork for the segmentation of smaller and more language specific units (e.g., words and phrases). Uncovering information about the weighting of cues in this early segmentation will tell us more about how infants go about segmenting these larger units and subsequently smaller units from continuous speech. In addition, segmentation of these units is a key step in language acquisition because so much information about the syntactic structure of the native language (for example, word order) may be gleaned from clauses and phrases. ? ? In a series of experiments infants' use of prosodic cues in their segmentation of clauses will be explored. The experiments feature prosodic cues one by one from both clausal and non-clausal units and examine whether infants' performance on segmentation tasks remains the same or worsens as the result of the loss of each cue or group of prosodic cues. In this way, information concerning the perceptual weighting of these cues is elucidated. ? ?
