  During speech, air from the lungs is forced past the vocal folds which
vibrate, producing sound. A pulsatile jet of air is formed downstream of the
vibrating folds which interacts with the various structures in the airway.
Currently, it is postulated that the way this jet interacts with the downstream
structures in the airway directly affects the quality of human speech. In order
to better understand this jet, it is desirable to visualize the jet in three
dimensions. We present the results of a method that reconstructs the three
dimensional velocity field using Synthetic aperture PIV (SAPIV)
\cite{Belden:2010}.
  SAPIV uses an array of high-speed cameras to artificially create a single
camera with a variable focal length. This is accomplished by overlapping the
images from the array to create a "focal stack". As the images are increasingly
overlapped, more distant image planes come into focus. 3D PIV is then performed
on the "refocused" focal stack to reconstruct the flow field in three
dimensions. SAPIV has the ability to track very high particle densities.
  Artificial self oscillating vocal folds made of silicone were driven with
compressed air infused with small glass microspheres. As the vocal folds
vibrated, the entrained microspheres were illuminated by a laser volume. Eight
high-speed cameras were used to capture images of the particles for SAPIV
postprocessing.
  SAPIV was able to successfully perform the first whole-field reconstruction
of the pulsatile jet emerging from the vocal folds. The ability to visualize
this jet will help researchers and clinicians better understand the physics of
speech production as well as improve the prevention, diagnosis, and treatment
of voice disorders.
