Ultrasound is increasingly common in speech and phonetics research as technology continues to improve. The first digital 3D/4D ultrasound system was utilized for speech research nearly a decade ago, but data access, processing, and visualization were limited to (non-speech) clinical imaging applications. Access to the raw (pulse-echo or scan-converted) image data is a critical step toward making 3D/4D ultrasound an effective tool for speech research. In addition, there is a need for technical characterization of 3D/4D ultrasound systems together with a presentation of their strengths and limitations for research.
Lulich, S. M., Berkson, K. H., & de Jong, K. (2018). Acquiring and visualizing 3D/4D ultrasound recordings of tongue motion. Journal of Phonetics, 71, 410-424.