Bunton Kate, Hoit Jeannette D
Department of Speech, Language, and Hearing Sciences, The University of Arizona, Tucson.
J Speech Lang Hear Res. 2018 Mar 15;61(3):549-560. doi: 10.1044/2017_JSLHR-S-17-0208.
The vocalizations of young infants often sound nasalized, suggesting that the velopharynx is open during the 1st few months of life. Whereas acoustic and perceptual studies seemed to support the idea that the velopharynx closes for vocalization by about 4 months of age, an aeromechanical study contradicted this (Thom, Hoit, Hixon, & Smith, 2006). Thus, the current large-scale investigation was undertaken to determine when the velopharynx closes for speech production by following infants during their first 2 years of life.
This longitudinal study used nasal ram pressure to determine the status of the velopharynx (open or closed) during spontaneous speech production in 92 participants (46 male, 46 female) studied monthly from age 4 to 24 months.
The velopharynx was closed during at least 90% of the utterances by 19 months, though there was substantial variability across participants. When considered by sound category, the velopharynx was closed from most to least often during production of oral obstruents, approximants, vowels (only), and glottal obstruents. No sex effects were observed.
Velopharyngeal closure for spontaneous speech production can be considered complete by 19 months, but closure occurs earlier for speech sounds with higher oral pressure demands.
年幼婴儿的发声往往听起来带有鼻音，这表明在出生后的头几个月里，腭咽是开放的。尽管声学和感知研究似乎支持这样一种观点，即腭咽在大约4个月大时会闭合以进行发声，但一项空气力学研究对此提出了反驳（汤姆、霍伊特、希克森和史密斯，2006年）。因此，开展了当前这项大规模调查，通过跟踪婴儿出生后的头两年，来确定腭咽在何时闭合以进行言语产生。
这项纵向研究使用鼻腔气流压力来确定92名参与者（46名男性，46名女性）在4至24个月大期间每月进行自发言语产生时腭咽的状态（开放或闭合）。
到19个月大时，腭咽在至少90%的发声过程中是闭合的，不过参与者之间存在很大差异。按语音类别来看，在发出口腔阻塞音、近音、元音（仅元音）和声门阻塞音时，腭咽闭合的频率从高到低。未观察到性别效应。
自发言语产生时的腭咽闭合在19个月时可被认为是完全的，但对于口腔压力要求较高的语音，闭合会更早发生。
