Presentation on theme: "Instrumentation: Vocal Fold Vibration 2/10/00. Glottogram Analyzes the vibratory pattern of the vocal folds Graph of the laryngeal source waveform Graph."— Presentation transcript:
Glottogram Analyzes the vibratory pattern of the vocal folds Graph of the laryngeal source waveform Graph of the visible glottal area over time Vibration of vocal folds creates: –Glottis alternately opens & closes –Motions create a triangular shaped wave –Baseline = closure –Peak = maximal opening
Glottogram Point of max opening Opening Closing OPEN CLOSED Width of area of glottis (% of Maximum) Open PhaseClosed Phase 1 Cycle (T)
Cinematography Motion picture technique of visualizing the vocal folds Fast filming- 50-4000 frames per second Pictures analyzed to measure glottal area Early method of viewing the vocal fold cycle
Cinematography High Speed Motion Camera Vocal Cords 4000 Watt Iridescent Lamp Mirror Lens Mirror
Stroboscopy Rapidly sampling vocal fold position at selected time intervals –Result is a slow motion analysis –Composite of samples from different cycles Waveform is sampled at a rate slightly lower than the repetition rate (F 0 ) to see vibration –What do you see if the F 0 = 100 Hz and the strob is sampling at 100 flashes per second?
Rigid Endoscopy Head must be tilted up & back for optimal vision.
Top: light pulses are regular & produced at the same frequency (still); Bottom: pulses regular but differ 1.5 Hz from the frequency of vibration (motion) Flash 1Flash 2Flash 3Flash 4 image 1image 2image 3image 4 composite image composite image
A B (A) Synchronized flash intervals, illumination occurring at same point of each cycle, motionless (B) Flash intervals occur at faster rate, results in motion.
Electroglottography (EGG) Record vocal fold vibration from 2 electrodes placed on either side of the neck As vocal folds open & close during vibration, the signal’s intensity changes Air = bad conductor (shows v.f. abduction) The electrodes sense resistance. Does not measure glottal area but the amount of tissue in contact with other tissue.
EGG Contact Area Ventilatory position Open Phase Closed Phase Different degrees of vocal fold contact during closed phase
Relationship of points in the Lx wave to medial contact of the vocal folds. EGG Waveform