| Summary: | 碩士 === 國立台北護理學院 === 聽語障礙科學研究所 === 95 === Purpose: Few studies investigated the effects of cochlear implantation on speaking rate and vowel formant characteristics and related speech intelligibility, especially in Mandarin. The purposes of this study are to report on the comparisons in speaking rate and vowel space area and its relationship to speech intelligibility between children with cochlear implants (CI) and children with normal hearing (NH). Method: Twenty-four elementary school Taiwanese children with CIs and 24 matched hearing controls were recorded as they read a double-syllable Mandarin intelligibility test, repeated prolonged phonation of /i/, /a/, and /u/ five times, respectively, and repeated sentences carrying /i/, /a/, and /u/ five times, respectively. Results: The results indicated that (1) the CI group had a 3.7 of 5-point rating in speech intelligibility and an average 75 % phoneme and tone correctness, compared to the NH group; (2) the CI group exhibited significantly longer speaking duration, resulting from longer articulation rate and larger pause proportion within sentences; (3) both the CI and NH groups exhibited vowel reduction phenomenon, although the extent to which was smaller in the CI group; (4) compared to the NH group, the CI group had a significantly smaller vowel space area in prolonged point vowel articulation, but not in carrier sentence recitation; and (5) the CI group exhibited significant relationship between vowel space and vowel intelligibility, but not consonant or tone intelligibility. Conclusions: It is concluded that the limitations of speech intelligibility in children with CI were due to segmenal and suprasegmental errors, slowed speaking rate resulting from slower articualtory movement and movement transitions, and abnormal patterns in vowel centralization and undershoot. Furthermore, F2 frequency range of Mandarin point vowels is a general valid index of speech intelligibility, except for lexical tone.
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