Rear pharyngeal wall placement during vowel production

Abstract

While the rear pharyngeal wall has been assumed to be stationary during speech, this needs to be confirmed. The present study used midsagittal magnetic resonance images to determine whether the posterior pharyngeal wall shows vowel-specific movement during the sustained production of 11 English vowels. Distances were measured between the most posterior portion of the vertebral body and the pharyngeal wall at four points. The first traversed the junction between the dens and body of the second vertebra (C2). The next three traversed the inferior border of the bodies of C2, C3, and C4. These ranged from a level just below the velopharyngeal port to one near the larynx. In preliminary measurements for one speaker, only the uppermost location showed significant variation due to vowel quality; at the other locations, differences were less than 1 mm. Further subjects are being studied. These findings confirm, at least for vowels, the assumption that the rear pharyngeal wall is stationary during speech. Therefore, midsagittal distances in the pharyngeal region can be inferred from measurements of the anterior pharyngeal wall in relation to the fixed features of the vocal tract. [Work supported by NIH Grant DC-02717.]

The use of ultrasound for linguistic phonetic fieldwork

“…One study (Stone 1990) found that for vowels, /s/ and /l/, only about 1 cm of the tip is lost (comparable to X-ray Microbeam and EMMA tracking systems, which typically position the first pellet 1 cm from the tip). Another study (Magen & Kang 2001) shows the stability of the rear pharyngeal wall during the full range of English vowels, suggesting that tongue root measurements alone are sufficient to approximate pharyngeal constrictions for English vowels. To further mitigate these limitations, additional transducer pressure can improve tongue tip imaging, and where more precise measurements are required, tracking devices can be used to correct for position.…”