<Original>A study on verbal communication : Phonetic characteristics of autistic children

Autism, which usually occurs in early childhood, is a complex developmental disorder accompanied by severe and usually permanent intellectual and behavioral deficits. Children with autism demonstrate several peculiar and bizarre characteristics, primarily in social interactions and communication. They also demonstrate qualitative impairment in verbal communication, such as 1) whispering, 2) high pitch, 3) monotonous or question-like speech, and 4) incomplete form or content of speech (lack of postpositional particles). However, studies of these symptoms are subjective and few studies have demonstrated objective evidences of verbal impairments. For this reason, we focused on objective evidence of "bizarre verbal communication" in autistic children. The purpose of this study was to clarify phoneme and syllable segmental characteristics, and prosodic characteristics of intonation in autistic children. Voice recordings were taken from 16 children (8 autistic and 8 normal children). The voice recordings were analyzed first quantitatively (word and sound frequency, word length, and word frequency contrasts), and secondly qualitatively (sound spectrogram of each word). A questionnaire eliciting qualitative impressions of the voice recordings was administered to 19 third-year speech therapy students. The combined spectrographic and impressionistic analyses revealed that baseline utterance of frequencies were higher for autistic children than for normal children. In addition, the following abnormalities were observed in the speech of some of autistic children; 1) lack of "S" and "J" sounds, 2) elevated intensity at the beginning of an utterance, and 3) sudden drop in energetic curve between sounds in one word. In conclusion, the voice spectrogram enabled us to both quantitatively and qualitatively analyze characteristics of verbal impairments in autistic children