Third International Conference on Spoken Language Processing (ICSLP 94)
Results obtained from a previous investigation of the acoustic characteristics of the velum using separate, simultaneous measurements of lip and nostril radiations suggested that nasal radiation was caused by the vibration of the velum. The current study used measurements of intraoral and intranasal sound pressures and velar movements to investigate the acoustic characteristics of the velum during vowel production. To observe changes in the acoustic properties of the velum, the transfer ratio of the section spanning the velum was analyzed and compared for nasalized vowels, non-nasalized vowels and nasal consonants. The results showed that the transfer ratio is larger in closed vowels than it is in open vowels.- The effect of the velum vibration on the transfer ratio was observed not only in non-nasalized vowels, but also in nasalized vowels. There is a consistent relationship between the height of the velar position, the transfer ratio and the nasal sound in a vowel section. Specifically, there is a higher velar position and larger transfer ratio and nasal sound for closed vowels, and a lower velar position and smaller transfer ratio and nasal sound for open vowels. The degree of velopharyngeal opening is strongly correlated to the stress position of a sentence. The velopharyngeal port opens more widely in the case of a nasal consonant following a syllable with a stress than it does in other cases.
Bibliographic reference. Dang, Jianwu / Honda, Kiyoshi (1994): "Investigation of the acoustic characteristics of the velum for vowels", In ICSLP-1994, 603-606.