Vibratory Regime Classification of Infant Phonation

Abstract

Infant phonation is highly variable in many respects, including the basic vibratory patterns by which the vocal tissues create acoustic signals. Previous studies have identified the regular occurrence of non-modal phonation types in normal infant phonation. The glottis is like many oscillating systems that, because of non-linear relationships among the elements, may vibrate in ways representing the deterministic patterns classified theoretically within the mathematical framework of non-linear dynamics. The infant's pre-verbal vocal explorations present such a variety of phonations that it may be possible to find effectively all the classes of vibration predicted by non-linear dynamic theory. The current report defines acoustic criteria for an important subset of such vibratory regimes, and demonstrates that analysts can be trained to reliably use these criteria for a classification that includes all instances of infant phonation in the recorded corpora. The method is thus internally comprehensive in the sense that all phonations are classified, but it is not exhaustive in the sense that all vocal qualities are thereby represented. Using the methods thus developed, this study also demonstrates that the distributions of these phonation types vary significantly across sessions of recording in the first year of life, suggesting developmental changes. The method of regime classification is thus capable of tracking changes that may be indicative of maturation of the mechanism, the learning of categories of phonatory control, and the possibly varying use of vocalizations across social contexts.

An initial study of voice characteristics of children using two different sound coding strategies in comparison to normal hearing children

“…It is through monitoring that the speaker is able to match the frequency heard to the frequency aimed to be produced. During the vocal maturation process, individuals develop phonatory control and the ability to vary vocal use in different situations, as a direct function of auditory feedback (Buder et al, 2008).…”

Emergence of Functional Flexibility in Infant Vocalizations of the First 3 Months

“…By 3 months, the protophones differentiate into at least three types (Buder et al, 2008): (a) vocants generally produced in the mid-pitch range (approximately 250–400 Hz) of each infant using a pattern of vocal fold vibration called normal phonation; this is the phonatory type that occurs overwhelmingly in syllables of speech, (b) squeals with high pitch (typically at least twice as high as the infant's mid pitch), often produced in loft or falsetto phonation, and (c) growls, which have either low pitch (typically half or less than the mid-pitch value), often with fry or “pulse” phonation, or noisy dysphonation (Stark et al, 1975; Oller, 1980; Holmgren et al, 1986). Audio-video examples of all three phonatory protophone types can be found at babyvoc.org, IVICT, and in Oller et al (2013, Supporting Information Appendix), and in the Supplementary Material to the present paper.…”

Vocal quality assessment: methodological approach for a perceptive data analysis

“…In this perspective, among the evaluation instruments available for clinical use, there are few scripts and scales based on theoretical models such as phonetic theory, as is the case of the Vocal Profile Analysis Scheme (VPAS) 14 . It is worth mentioning that the use of instruments of Phonetics in Speech-Language Pathology clinics has contributed to a detailed identification of speech structures in cases of speech disorders 15,16 , as well as speech control cues in the process of language acquisition of children with and without hearing impairment (HI) from early ages [17][18][19] . In addition, the use of such instruments may offer possibilities for the characterization of language sonority and linguistic variants 20 .…”