The Articulatory Phonetics of /r/ for Residual Speech Errors

Abstract

Effective treatment for children with residual speech errors (RSEs) requires in-depth knowledge of articulatory phonetics, but this level of detail may not be provided as part of typical clinical coursework. At a time when new imaging technologies such as ultrasound continue to inform our clinical understanding of speech disorders, incorporating contemporary work in the basic articulatory sciences into clinical training becomes especially important. This is particularly the case for the speech sound most likely to persist among children with RSEs-the North American English rhotic sound, /r/. The goal of this article is to review important information about articulatory phonetics as it affects children with RSE who present with /r/ production difficulties. The data presented are largely drawn from ultrasound and magnetic resonance imaging studies. This information will be placed in a clinical context by comparing productions of typical adult speakers to successful versus misarticulated productions of two children with persistent /r/ difficulties.

Figure 1

Types of American English tongue configurations for /r/ as identified by Delattre and Freeman (1968) from x-ray tracings of 44 subjects. Only types seen in “rhotic” dialects are shown. All types were found in both prevocalic (syllable onset), syllabic (nucleus) and postvocalic (syllable rime) positions. Tongue configuration types have been renumbered for purposes of this paper. Figure adapted with permission from Hagiwara (1995). Type #1 and Type #4 are examples of configurations typically called bunched (#1) and retroflex (#4). They correspond roughly to images shown in Figure 2 for Speakers 22 and 5.

Figure 2

Midsagittal Magnetic Resonance images of 21 different typical adult native speakers of rhotic dialects of American English speakers producing sustained /ṛ/ as in the word “pour”. All images are shown in the midsagittal plane facing left. As noted in the text, similar vocal tract shapes have been recorded dynamically from the same set of speakers in prevocalic positions using ultrasound. There are 22 images because Speaker 5 was trained to produce a retroflex shape similar to that of #4 in Figure 1, as well as his natural bunched shape, similar to that of #1 in Figure 1. Note that MR images reflect the density of hydrogen atoms in tissue vs. air. Bone, air and teeth all appear as dark areas on the image, meaning that it is not possible to separate teeth from air when they are contiguous. Codes identifying each speaker are numerical and appear at the bottom right edge of each image.

Figure 3

Corresponding Midsagittal (left) and coronal (middle and right) plane images of Speakers 22 and 5 from Figure 2. Red lines labelled 1 and 2 on the midsagittal image indicate the location of the coronal slice. The lateral edges of the tongue at this point along the vocal tract are shown by red arrows on the coronal slice images. As with Figure 2, both air and teeth are shown as dark, while tissue is shown as gray or white depending on hydrogen atom density. The palate is shown as a bony ridge above the tongue.

Figure 4

Modified Barium Swallow image of elderly male speaker of American English producing coda /r/ as in “year” with barium medium showing contrast between tongue sides and midline groove. The leftmost panel shows the untouched image. The rightmost panel shows outlines drawn along to show the contrast between the sides of the tongue and the midline groove.

Figure 5

Corresponding Magnetic Resonance Images in Midsagittal and Axial (Horizontal) planes from Typical Adult Speaker 5 of Figure 2 at level of tongue tip (left) and level of narrowest constriction between tongue root and back wall of pharynx (right). Note that a section of the velum hanging in the airspace behind the tongue dorsum can be seen as a bar of flesh bracketed by dark areas before and behind.

Figure 6

Magnetic Resonance (MR) Images of two children in therapy for Residual Speech Sound Disorders (RSSD). Child Speaker 1 (age 10.5) is shown on the left and Child Speaker 2 (age 9.0) is shown on the right. Sustained misarticulated versions of /ṛ/ are shown above versions judged to be “good”.