Vowel Acoustic Space Development in Children: A Synthesis of Acoustic and Anatomic Data

Abstract

Vowel development is expressed as follows: (a) establishment of a language-appropriate acoustic representation (e.g., F1-F2 quadrilateral or F1-F2-F3 space), (b) gradual reduction in formant frequencies and F1-F2 area with age, (c) reduction in formant-frequency variability, (d) emergence of male-female differences in formant frequency by age 4 years with more apparent differences by 8 years, (e) jumps in formant frequency at ages corresponding to growth spurts of the VT, and (f) a decline of f0 after age 1 year, with the decline being more rapid during early childhood and adolescence. Questions remain about optimal procedures for VT normalization and the exact relationship between VT growth and formant frequencies. Comments are included on nasalization and vocal fundamental frequency as they relate to the development of vowel production.

Range and Precision of Formant Movement in Pediatric Dysarthria

“…In children, abnormal speech movements are occurring within the context of substantial shifts in vocal tract size and geometry, as well as in articulatory control and coordination. Growth of the vocal tract lowers formant frequencies, whereas refinement of speech motor control with age results in improved accuracy in producing acoustic targets (Vorperian & Kent, 2007). Speech movement variability is known to be greater in children than adults (Smith & Zelaznik, 2004;Walsh & Smith, 2002), and coordination of articulatory movements changes dramatically over the first 6 years of life (Green, Moore, Higashikawa, & Steeve, 2000).…”

On the Use of Voice Signals for Studying Sclerosis Disease

“…The vowel metric is commonly used in clinical research to associate dysarthria conditions with pathological vocal signals [43]. In the presence of dysarthria, speech is often characterized by vowel centralization as a result of an undershooting of articulatory targets.…”

Implementing two treatment approaches to childhood dysarthria

“…Children ' s age, vocal tract anatomy, type and degree of motor defi cit, phonological development, individual characteristics, and growth spurts (Vorperian & Kent, 2007) are likely contributing factors. Further research is needed to explore the relationships among speech treatment, expansion of vowel space, intelligibility, and communicative participation by children with CP.…”

“…Vowel area in Hz was calculated (on Excel) using the formula of the area of an irregular quadrilateral (Vorperian & Kent, 2007) Table II). These calculations confi rmed that vowel space expanded by 202,535 Hz for P1.…”