Tracking articulator movements from X-ray motion films
- See also Articulator manoeuvres for more detailed examples
- Vocal tract profiles are traced frame by frame from the X-ray motion film
- Tracings for selected sequences are superimposed to track the movement of individual articulators, for example:
- The upper lip with respect to the maxilla
- The mandible with respect to the maxilla
- The lower lip with respect to the mandible
- The tongue body with respect to the mandible
- The tongue blade with respect to the tongue body
- The composite pictures are then separated back to a series of individual pictures to be played in an animation sequence.
- Each frame is scanned at high resolution from the film, using a 35mm film scanner
- A scan is opened in a drawing program
- The X-rayed centimetre scale is used to adjust scale
- The midsagittal vocal tract outline is traced on a new transparent layer
- The tracing is saved with transparent background
Identifying articulator movements
- Consecutive tracings are superimposed and compared in order to reveal local shifts in contours, reflecting movement.
- This example shows tracings from five consecutive film frames, superimposed relative to the mandible.
- This captures movements that can be attributed to activity in the muscles of the lower lip and the tongue, that are anchored to the mandible
- In this example, the tongue blade was depressed away from the alveolarpalatal region (withdrawal from a vibrant [r]), while the tongue body was elevated (towards the hard palate) and advanced (expanding the pharyngeal region) for an oncoming [e]
- The speaker did not move the lower lip during this particular sequence.
Combining individual profiles into animation sequences
- Pictures 1-5 below are separations from the example above.
- These are then organized into a GIF animation
- On a web page, a GIF animation displays the pictures rapidly, creating an illusion of movement, like picture 6
- The actual speed of presentation depends on the performance of your computer, and will usually be slower than the original speech. The original duration of this sequence was 67 msecs.
© Sidney Wood and SWPhonetics, 1994-2012