Variability in vowel formant frequencies of children with cerebral palsy

Variability in vowel formant frequencies of children with cerebral palsy Li-mei Chen Department of Foreign Languages and Literature, National Cheng Kung University leemay@mail.ncku.edu.tw Yung-Chieh Lin Department of Pediatrics, National Cheng Kung University Wei Chen Hsu and Fang-hsin Liao Department of Foreign Languages and Literature, National Cheng Kung University 摘要 腦性麻痺為發展性運動神經障礙，而研究腦性麻痺語言特徵及其發展模式對於幼童 早期語言發展的了解相當重要。母音在初期語言發展就已出現並且是了解語音聲學特性 的關鍵。本研究旨在檢視五位腦性麻痺嚴重程度不同以及年齡層介於三到七歲的腦性麻 痺幼童之母音共振峰頻率的差異。測量 F1 和 F2 的變化、母音空間分佈、母音空間面積。 本研究結果顯示：1)三歲到七歲之間沒有發現 F2 明顯的下降；2) 母音橢圓形軌跡都有 明顯的重疊；3)母音分佈沒有顯著的擴張，研究結果顯示這五位腦性麻痺小朋友有語言 運動神經不協調和發音發展遲緩的情形。 關鍵字: 母音共振峰頻率、母音空間、腦性麻痺、學習國語幼童 Abstract Cerebral palsy (CP) is a developmental motor disorder and the study of the speech characteristics and developmental speech patterns may provide valuable information on early speech development. Vowels appear early in speech development and they are central to the understanding of the acoustic properties of speech. Therefore, the current study aimed to examine the differences of vowel formant frequencies among five children with cerebral palsy in different severity ranging from ages 3 to 7. First and second vowel formants (F1 and F2) were measured to investigate: 1) the changes of the F1 and F2 values, 2) vowel space, and 3) the vowel space area in CP children of different ages and severity. The major findings are: 1) There was no obvious decline in F2 values from 3 to 7 years old, which indicated delayed speech development; 2) The overlapping ellipses of all vowel spaces illustrated unstable motor control in all the five children; and 3) The five CP children had centralized corner vowels and there was no expansion of vowel spaces at different ages. This indicated their limited motor control. Keywords: vowel formant frequencies, vowel space, cerebral palsy, Mandarin-speaking Proceedings of the Twenty-Fifth Conference on Computational Linguistics and Speech Processing (ROCLING 2013) 260 children 1. Introduction Cerebral palsy is regarded as the most common cause of severe motor disability in children who are attributed to non-progressive disturbances that occurred in the developing infant brain [ 1]. Estimation from several different developed countries reported that 1.2-3.0 per 1000 children were diagnosed with cerebral palsy [2][3]. Vowels are central to the understanding of the acoustic properties for speech, and vowels appear early in speech development. Children achieve high degree of accuracy in producing vowels by the age of 36 months [4]. Therefore, the current study focused on vowel acoustical characteristics in five CP children of different ages. 2.Methodology 2.1.The participants Five children with cerebral palsy participated in current study for investigating the differences of vowel formant in their speech production. General background information is described as follows. Table 1. CP participants Gender Age (in year; month, day) Severity of Impairment CFCS CP1 Male 2;5,13 Moderate Level II which distributed that the child is effective message sender/receiver with both unfamiliar and familiar communication partners but in a slow path CP2 Male 2;9,16 Most Severe Level IV which indicated that the child seldom effective message sender/receiver even with familiar partners CP3 Male 3;11,6 Moderate Between level IV (Self-Mobility with Limitations; May Use Powered Mobility) in between 4th and 6th birthday. CP4 Male 4;11,16 Severe Between level III and IV CP5 Male 6;5,14 Severe Between level IV (Self-Mobility with …

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