Precision Stroboscopy and Continuous Speech

Precision stroboscopy links stroboscopic analysis and the triggering speech or Laryngograph® waveforms. These signals can themselves provide the basis for a non-invasive monitoring of several minutes of continuous speech which would be impossible while using a rigid endoscope. When such analysis is linked to the stroboscopic findings a more complete picture can be obtained.

The image above right is the seventh in a sequence of eight images representing one vocal fold contact cycle.

The associated Speech and Laryngograph® waveforms confirm that the image was taken in the middle of the open phase and that the frequency of vibration was 310Hz. This is a relatively high frequency for a woman.

The detailed analyses based on the two-minute speech sample show how this speaker coped with the effects of the vocal fold scarring shown in the single stroboscopic image.

The first order distribution of fundamental frequency (DFx1) shows three peaks with the main one being at the abnormally high fundamental frequency at which the stroboscopic image was taken.

The cross plot of vocal fold contact quotient v fundamental frequency (QxFx2) shows that this main mode is achieved with the use of a high closed quotient which is, again, unusual in the higher frequency range for women. In auditory terms the distributions give the impression of a very hoarse, irregular voice with an unnaturally high-pitched component.

Left vocal fold scarring
In the figure above, the image shows a single shot in the middle of the open phase, from a stroboscopic sequence using LxStrobe to cover the interval of one period. The acoustic, Laryngograph® and strobe trigger (centre) signals are beneath.