Universal Intrasyllabic Patterns in Early Acquisition Barbara L. Davis † and Peter F. MacNeilage ‡ † The University of Texas at Austin, Austin, TX E-mail: babs@mail.utexas.edu , macneilage@mail.utexas.edu ABSTRACT Universal phonetic patterns can be observed in babbling and early speech when infants produce rhythmic vocalizations that show structural similarities as well as differences from mature speakers. The Frame/Content perspective [1] illuminates underlying principles motivating intrasyllabic, consonant and vowel patterns observed in these early speech-like vocal sequences. According to this perspective, lack of articulator movements independent of the mandible in vocal sequences result in intrasyllabic co-occurrences of labial consonants with central vowels, coronal consonants with front vowels, and dorsal consonants with back vowels. As complexity emerges in consonant clusters, vocal sequences retain regularities of patterning predicted by the Frame/Content perspective. In addition, these patterns appear to be resilient in the face of auditory perceptual deficit. Although syllable use is low in infants with hearing impairment, when syllables are produced they follow the patterns found in hearing infants and predicted by the Frame/Content perspective. (143) 1. INTRODUCTION The syllable is a universal structure found in all modern languages. The most frequent syllable type across languages is the consonant-vowel (CV) sequence, either in isolation or in a series of CV alternations [2]. The Frame/Content perspective proposes that the rhythmic close and open alternation of the mandible, resulting in the the CV structure, is a basic behavior of the production system whereby mandibular elevation results in the percept of a consonant and relative depression of the mandible enables resonance properties related to the percept of a vowel. This CV percept is proposed as being an emergent property of the biomechanical characteristics of the speech production mechanism functioning in the time domain. These consonant-vowel alternations, based on rhythmic mandibular oscillation, have been asserted to have historical roots in chewing, sucking, and licking behaviors. These ingestive cyclicities could have been co- opted for an oral communication system when accompanied by phonation [3]. This conceptualization provides a potential link between the CV pattern in modern languages and precursor behaviors, thus enabling a potential for a deep historical level of explanation for the most basic structures found in modern languages. Acquisition of speech production skill has been a frequent paradigm used for exploration of regularities in phonetic patterning in languages. The value of exploration of the earliest phases of speech acquisition lies in the potential for understanding the most complex system of serial action accomplished by the body when it is in its formative, and potentially most simple, phases of expression. These early rhythmic vocal sequences can be seen as exploitation of the most basic characteristics of the production mechanism by an immature organism in order to accomplish serial action. Comparative methodologies focusing on similarities and differences between infant vocal patterns and language patterns can reveal potentially universal phonetic structures that have been retained in patterning even as the pressure for message complexity increases in mature speakers. In this regard, the comparison of pre-linguistic vocal patterns, when there is no message transmission involved, with earliest message- related patterns in early words, can also potentially help to understand the ways in which vocal patterns available to the infant in babbling are shaped by the need to accomplish intelligible communication in the first word period and beyond. General Characteristics of Early Infant Vocalizations Outlining the facts of acquisition is an important first step to consideration of their importance in understanding the origins of intrasyllabic patterns. Although consonants and vowels are probably not controlled as separate entities in babbling (7-12 months) or first words (12-18 months), most data exploring these stages have come from phonetic transcription studies using these categories. These studies have shown strong similarities in sound preferences across different communities, suggesting a universal basis for babbling and earliest stages of speech production. Consonantal phones most frequently reported are stops [b], [d], nasals [m], [n], glides [j], [w], and [h]. While coronal (tongue tip) consonants tend to predominate in babbling, labial (lip) consonants are more frequent in first words. Dorsal (tongue body) consonants (i.e. [g]) are relatively infrequent. Mid and low front and central vowel qualities are reported in both transcription and acoustical studies. Most frequent syllable types are CV, (i.e. “ba”), and CVCV (i.e. “baba”). In the time domain, the infant’s development of both babbling and early speech patterns is characterized as operating within an overall rhythmic envelope consisting of mouth close-open movements with resultant alternations between non-resonant and resonant acoustic output. 2. DATA What types of data are available to describe the course of phonetic acquisition in this period? Our research program over the past twenty years has centered on longitudinal 15th ICPhS Barcelona 379 ISBN 1-876346-48-5 © 2003 UAB