Journal Article A study on transvelar coupling for non-nasalized sounds

Dang, Jianwu  ,  Wei, Jianguo  ,  Honda, Kiyoshi  ,  Nakai, Takayoshi

139 ( 1 )  , pp.441 - 454 , 2016-01 , Acoustical Society of America
Previous studies have found that the velum in speech production may not only serve as a binaryswitch with on-off states for nasal and non-nasal sounds、 but also partially alter the acousticcharacteristics of non-nasalized sounds. The present study investigated the unique functions ofthe velum in the production of non-nasalized sounds by using morphological、 mechanical、 andacoustical measurements. Magnetic resonance imaging movies obtained from three Japanesespeakers were used to measure the behaviors of the velum and dynamic changes in the pseudo-volumeof the pharyngeal cavity during utterances of voiced stops and vowels. The measurements revealed nosignificant enlargements in the supraglottal cavity as subjects uttered voiced stops. It is found that thevelum thickness varied across utterances in a way that depended on vowels、 but not on consonants.The mechanical and acoustical observations in the study suggested that the velum is actively controlledto augment the voice bars of voiced stops、 and nostril-radiated sound is one of the most important sourcesfor voice bars、 just as is laryngeal wall vibration. This study also proposed a two-layer diaphragmmodel that simulates transvelar coupling during the production of non-nasalized speech sounds. Thesimulation demonstrated that the model accurately represented the basic velar functions involved inspeech production.

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