This study investigated the tongue movement of lateral articulation which is seen in error sounds of vowel /i/, /∫, t∫, d _??_, ç, s, ts, dz/ and consonants followed by the vowel /i/ or semi vowel /j/. Lateral articulation was observed by electro tooth-palatography.
The results were as follows.
1. The tongue came into complete contact with the hard palate and all occlusal and palatal surfaces of the maxillary molars on the non-air-stream side of the dental arch.
2. On the air-stream side, the tongue did not come into contact with any molar occlusal surfaces but only with the palatal surface of the preterminal molar while producing vowel /i/ and fricatives of lateral articulation.
3. The tongue came into contact with all molars on both sides of the dental arch while producing plosives and liquids of lateral articulation but these palatograms showed deviate patterns to the non-air-stream side as a whole.
From these results, articulatory movement of lateral articulation can be defined as follows. After the tongue dorsum contacts the hard palate and air enters the oral cavity along the palatal surface of the terminal molar, sounds are produced by the margin of the tongue and the palatal surface of the preterminal molar, then air is forced out from the occlusal surface of the molar to the buccal groove, namely laterally, rather than from the middle of the palate.
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