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ERIC Number: EJ1034520
Record Type: Journal
Publication Date: 2014-Apr
Pages: 13
Abstractor: As Provided
Reference Count: N/A
ISSN: ISSN-1092-4388
Accuracy and Precision of a Custom Camera-Based System for 2-D and 3-D Motion Tracking during Speech and Nonspeech Motor Tasks
Feng, Yongqiang; Max, Ludo
Journal of Speech, Language, and Hearing Research, v57 n2 p426-438 Apr 2014
Purpose: Studying normal or disordered motor control requires accurate motion tracking of the effectors (e.g., orofacial structures). The cost of electromagnetic, optoelectronic, and ultrasound systems is prohibitive for many laboratories and limits clinical applications. For external movements (lips, jaw), video-based systems may be a viable alternative, provided that they offer high temporal resolution and submillimeter accuracy. Method: The authors examined the accuracy and precision of 2-D and 3-D data recorded with a system that combines consumer-grade digital cameras capturing 60, 120, or 240 frames per second (fps), retro-reflective markers, commercially available computer software (APAS, Ariel Dynamics), and a custom calibration device. Results: Overall root-mean-square error (RMSE) across tests was 0.15 mm for static tracking and 0.26 mm for dynamic tracking, with corresponding precision (SD) values of 0.11 and 0.19 mm, respectively. The effect of frame rate varied across conditions, but, generally, accuracy was reduced at 240 fps. The effect of marker size (3- vs. 6-mm diameter) was negligible at all frame rates for both 2-D and 3-D data. Conclusion: Motion tracking with consumer-grade digital cameras and the APAS software can achieve submillimeter accuracy at frame rates that are appropriate for kinematic analyses of lip/jaw movements for both research and clinical purposes.
American Speech-Language-Hearing Association (ASHA). 10801 Rockville Pike, Rockville, MD 20852. Tel: 800-638-8255; Fax: 301-571-0457; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Research
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A