Copyright © American Speech-Language-Hearing Association From: A Multidimensional Investigation of Children's /r/ Productions: Perceptual, Ultrasound, and Acoustic Measures Am J Speech Lang Pathol. 2013;22(3):540-553. doi:10.1044/1058-0360(2013/12-0137) Legend: Ultrasound images illustrating children's tongue shapes for /r/. The top image is an example of a retroflex /r/ that was produced by IS1. The arrow pointing to the reflection above the main tongue body indicates where the tip of the tongue is curled back and touching the alveolar ridge. The middle image is an example of a bunched /r/ that was produced by TS1. The bottom image is an example of an undifferentiated /r/ that was produced by IS2. This image is annotated to illustrate the metric used to measure curvature degree and location, based on Ménard et al. (2012). Date of download: 11/15/2017 Copyright © American Speech-Language-Hearing Association