Corrected high-frame rate anchored ultrasound with software alignment.

ABSTRACT

PURPOSE: To improve lingual ultrasound imaging with the corrected high frame rate anchored ultrasound with software alignment (CHAUSA; Miller, 2008) method. METHOD: A production study of the IsiXhosa alveolar click is presented. Articulatory-to-acoustic alignment is demonstrated using a Tri-Modal 3-ms pulse generator. Images from 2 simultaneous data collection paths, using dominant ultrasound technology and the CHAUSA method, are compared. The probe stabilization and head movement correction paradigm is demonstrated. RESULTS: The CHAUSA method increases the frame rate from the standard National Television System Committee (NTSC) video rate (29.97) to the ultrasound internal machine rate--in this case, 124 frames per second (fps)--by using Digital Imaging and Communications in Medicine (DICOM; National Electrical Manufacturers Association, 2008) data transfer. DICOM avoids spatiotemporal inaccuracies introduced by dominant ultrasound export techniques. The data display alignment of the acoustic and articulatory signals to the correct high-frame rate (FR) frame (± 4 ms at 124 fps). CONCLUSIONS: CHAUSA produces high-FR, high-spatial-quality ultrasound images, which are head corrected to 1 mm. The method reveals tongue dorsum retraction during the posterior release of the alveolar click and tongue tip recoil following the anterior release of the alveolar click, both of which were previously undetectable. CHAUSA visualizes most of the tongue in studies of dynamic consonants with a major reduction in field problems, opening up important areas of speech research.