Maximal vowel space method in analysis of vowels in prelingual speech phase

Abstract

The main problems in the analysis of vowels which occur in prelingual speech phase are centralization of utterance and unknown dimension of vocal tract. Most researches in this field are based on the analysis of maximal vowel space (MVS) because discrimination of vowels is very difficult in this early period. MVS analysis includes the estimation of vocal tract (VT) physical dimensions. The aim of this research was to estimate and define changes in vowel pronunciation during prelingual speech phase. The analysis and voice recording were performed in a two month old child until he turned one. The recording was performed in 42 sessions, on average 4 sessions every month. Sound segments that look like vowel pronunciation were extracted from the recordings and were used for the formant frequencies estimation by PRAAT software. The Burg method was used for formant frequency estimation. Research results showed that MVS can be used in diagnostic procedure from a child's earliest age. MVS analysis is appropriate for a child's earliest age as a child needs to pronounce individual phonemes, and does not need to respond to speech stimuli. These results need to be confirmed on a larger sample when extended analysis should define criteria for discrimination of typical and atypical formant frequencies.

Keywords

• prelingual phase
• vocal tract
• maximal vowel space
• vowel formant frequencies