An Acoustic Analysis of Fricatives Produced by Typically Developing Child and Adult Speakers of Oromo.
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Date
2019-03
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AAU
Abstract
The present study was aimed to investigate word initial and medial voiceless fricatives /f,
s, ʃ, h/ produced by typically developing children between the age of 3 and 6 and adult
speakers of Haraghe Oromo dialect. The study investigated whether fricatives were
distinct as a function of noise duration, normalized amplitude, and spectral features. The
work included fricatives both in singleton and geminate forms. The word initial fricatives
were all in singleton form because word or syllable initial geminationation is not
permissible in Oromo. The extent to which the sounds vary as a function of vowel
context, speakers‟ age and gender in both phonetic contexts was investigated. Among the
parameters analyzed, fricative duration, normalized amplitude and the first three spectral
moments (spectral mean and spectral standard deviation and spectral skewness) were
more effective to discriminate fricatives. But only the third spectral moment in the CV
and VCV fricatives and the second spectral moment in the VCV fricatives distinguished
all fricatives in terms place of articulation. The spectral kurtosis was the least or almost
not robust cue to discriminate fricatives. Similarly, locus equation did not discriminate
fricatives. The result supports the claim that locus equation is not a salient acoustic cue to
distinguish fricatives.In the study anatomical, physiological and developmental or behavioral factors played roles to bring variations as a function of place, vowel, age and gender. Surprisingly, gender difference was observed at early age which has been speculated to be conditioned by developmental or behavioral factors. The difference between geminate and singleton fricatives was evident both in durational and spectral attributes indicating that the two phonemes vary temporally and physiologically. In the CV context the voiceless glottal fricative behaved predominantly like vocalic segments than consonants, especially in having highly elevated average measures of spectral skewness and kurtosis. Among all fricatives /s/ turned out to be the most resistant to coarticulation and the least to be classified by the linear discriminant analysis. This typical nature of the sound may indicate that it was the last to be acquired by children among the test fricatives.
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Child and Adult Speakers of Oromo