2013 Volume 56 Issue 4 Pages 298-305
To evaluate the production of vowels after cochlear implantation, the first and second formant frequencies (F1 and F2) of the five Japanese vowels were measured in 4 children with cochlear implants. The results were compared between the children with deafness and severe hearing loss and those with normal hearing reported previously.
In only one child, the formant frequencies of all five vowels were located within normal range. The other 3 children showed significant deviation from the normal range in some vowels. In all 4 children, the formant frequencies of /a/ distributed almost within the normal range. However, for the other 4 vowels (/i/, /u/, /e/ and /o/), deviation from the normal frequency range was observed in some children.
When the ratio of the maximum and minimum values of F1 and F2 was compared with that in the normal hearing children, there was no significant difference of the F1. On the other hand, the values of F2 were smaller than those in normal children.
The characteristics of the formant frequencies in the children with cochlear implants were similar to those in the children who were deaf with severe hearing loss. The utterance impairment seen in cochlear implant children can be explained by insufficient movement of the tongue as observed in children with deafness and severe hearing loss.
