Vowels Development in Babbling of typically developing 6-to-12-month old Persian-learning Infants.
OBJECTIVE
Pre-linguistic vocalizations including early consonants, vowels, and their combinations into syllables are considered as important predictors of the speech and language development. The purpose of this study was to examine vowel development in babblings of normally developing Persian-learning infants.


METHODS
Eight typically developing 6-8-month-old Persian-learning infants (3 boys and 5 girls) participated in this 4-month longitudinal descriptive-analytic study. A weekly 30-60-minute audio- and video-recording was obtained at home from the comfort state vocalizations of infants and the mother-child interactions. A total of 74:02:03 hours of vocalizations were phonetically transcribed. Seven vowels comprising /i/,/e/,/a/,/u/,/o/,/ɑ/, and /ә/ were identified in the babblings. The inter-rater reliability was obtained for 20% of vocalizations. The data were analyzed by repeated measures ANOVA and Pearson's correlation coefficient using SPSS software version 20.


RESULTS
The results showed that two vowels /a/ (46.04) and /e/ (23.60) were produced with the highest mean frequency of occurrence, respectively. Regarding front/back dimension, the front vowels were the most prominent ones (71.87); in terms of height, low (46.78) and mid (32.45) vowels occurred maximally. A good inter-rater reliability was obtained (0.99, P < .01).


CONCLUSIONS
The increased frequency of occurrence of the low and mid front vowels in the current study was consistent with previous studies on the emergence of vowels in pre-linguistic vocalization in other languages.
a Department of Speech Therapy , University of Social Welfare and Rehabilitation Sciences , Tehran , Iran.
Mina
M
Fotuhi
a Department of Speech Therapy , University of Social Welfare and Rehabilitation Sciences , Tehran , Iran.
Fariba
F
Yadegari
b Pediatric Neurorehabilitation Research Center, University of Social Welfare and Rehabilitation Sciences , Tehran , Iran.
Robab
R
Teymouri
D000162:Acoustics; D000367:Age Factors; D000704:Analysis of Variance; D002663:Child Language; D005260:Female; D006801:Humans; D007223:Infant; D018730:Infant Behavior; D007492:Iran; D008137:Longitudinal Studies; D008297:Male; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography; D013061:Speech Acoustics; D014741:Video Recording; D014833:Voice Quality
Development; normal infants; pre-linguistic; vocalization; vowel