Vowel variability and contrast in Childhood Apraxia of Speech: acoustics and articulation.

Phoneme production may be affected by limited speech motor control in Childhood Apraxia of Speech (CAS), with a general instability of acoustic targets across multiple repetitions of speech stimuli. This acoustic and Ultrasound Tongue Imaging (UTI) study shows that increased variability and reduction of contrast in vowel production is found in native Italian speakers with CAS, particularly as far as the height dimension is concerned. The data suggest that vowel production should play a major role in CAS diagnosis and treatment. Moreover, this study shows that a combined acoustic and articulatory approach allows direct observation of lingual dynamics together with an estimation of changes in the acoustic dimension. The two dimensions are shown not to correspond in a straightforward way in the speech of children with CAS, and encourage consideration of articulatory compensation strategies aimed at saving the acoustic identity of vowels.