단어의 조음복잡성 및 문장 내 위치에 따른 경직형 마비말장애 화자의 자음정확도와 말명료도

Abstract

Due to the damage to the central and/or peripheral nervous system, people with spastic dysarthria have abnormal muscular movements for speech production, which results in imprecise articulation. Those with spastic dysarthria have additional difficulty in proper control of muscular movements when they try to produce phonologically complex words. It is assumed that this causes articulation errors and has a negative effect on speech intelligibility. It is also expected that their articulation ability may differ according to the position of words in a sentence. Therefore, this study aimed to examine whether there were any differences in the percentage of consonants correct(PCC) and speech intelligibility according to the level of articulatory complexity (levels 1 to 4) and position (at the beginning and in the middle of a sentence) of the target words when the speakers with mild-to-moderate spastic dysarthria produce sentences. Participants of this study were 5 speakers with mild-to-moderate spastic dysarthria and 50 normal listeners. In order to examine the articulatory characteristics of the speakers in structured sentences, carrier phrase sentences consisting of 3 eojeols were used. Twenty target words were selected from the word lists of the Assessment of Phonology and Articulation of Children. The Korean Articulatory Complexity Index was used to classify the target words into 4 articulatory complexity levels; the speakers were requested to produce sentences with diversified positions of words in the sentences (at the beginning and in the middle of a sentence). The researcher listened to the sentences produced by the speakers, and the PCC scores were calculated; 10 normal listeners were requested to listen to the speech samples of 1 speaker and the scores of speech intelligibility were calculated. The results of this study were as follows: (1) As for the PCC of the target words according to the articulatory complexity and position of words in sentences, the PCC of level 4 was significantly lower than the PCC of level 1; the PCC of the words located in the middle of the sentence was significantly lower than the PCC located at the beginning of the sentence. (2) As for the speech intelligibility of the target words according to the articulatory complexity and position of words in sentences, there were significant differences between all levels except between levels 2 and 4; the speech intelligibility of the words located in the middle of the sentence was significantly lower than the speech intelligibility located at the beginning of the sentence. (3) Analysis of the correlation between the PCC and the speech intelligibility of the target words according to the articulatory complexity and position of words in sentences shows that at the level 4, the correlation coefficient between the PCC and the speech intelligibility of the target words was positive with .89 at the beginning of the sentence. As for the correlation between the PCC and the speech intelligibility of the target words according to the position of words in sentences, the correlation coefficient between the PCC at the start of sentences and the overall PCC was .98, which is also a very high level of positive correlation; the correlation coefficient between the speech intelligibility at the start of sentences and the overall speech intelligibility was 1.00, which is a very high level of positive correlation. The correlation coefficient between the speech intelligibility in the middle of sentences and the overall PCC was .90, which is a very high level of positive correlation. As for the correlation between the percentage of consonants correct and the speech intelligibility of the target words according to the level of articulatory complexity, the correlation coefficient between the percentage of consonants correct at the level 3 and the overall percentage of consonants correct was .95, which is a very high level of positive correlation. The clinical implication of this study lies in the fact that it has confirmed the characteristics of the articulation ability and the speech intelligibility according to the articulatory complexity and position of words in sentences that affect the articulation of words at the level of sentence that is a linguistic unit used in daily life by the speakers with spastic dysarthria. The results of this study suggest that for evaluation and intervention for the speakers with spastic dysarthria, both the level of articulatory complexity and the position of words in sentences should be considered.