Ultrasound technology has been shown to be a new tool in the treatment of speech sound disorders. It helps diagnose problems and can provide visual feedback to help children correct errors they make in producing the sounds of their language. Recent advances have made this imaging technique more accessible to clinicians, both in terms of price and of ease of use. The present proposal will facilitate the translation of the research into clinical practice so that a wide range of clients can begin to benefit from these technological advances. One part of the project will test the usefulness of looking at the types of tongue shapes used by children with speech problems. Research has found that some children use tongue shapes that are relatively adult-like but incorrect, while others use an undifferentiated shape-that is, a shape that shows limited accommodation to different sounds. These undifferentiated tongue shapes may indicate that a different kind of therapy is called for. We will test two kinds of therapy on misarticulating children. We expect to find that knowing whether a child uses undifferentiated shapes or not (as seen with ultrasound imaging) will allow the selection of the better treatment program. A particularly difficult sound is that of /r/, as i right, try and car. Ultrasound imaging can help children see what their tongue should be doing to get a perceptually correct sound. We will further test elements of this feedback procedure so that we can provide evidence-based guidance for implementing ultrasound treatment in clinics everywhere. Further support for the approach will come from magnetic resonance imaging (MRI) of the tongue in children with good and poor /r/ pronunciation. We will validate ultrasound imaging of the tongue against MRI images, and we will also collect MRI images that can be used to model appropriate tongue shapes for children. While our MRI images from adults have proven useful in helping children pick an appropriate tongue shape for /r/, we predict that MRI images of children will be even more informative. Improving the articulation of this common sound will help thousands of children.