High-speed photography is the science of taking very fast pictures. It records fast-moving objects as a photographic images onto a storage medium, often digital. After recording, the stored images can be played back in slow-motion.
A normal motion picture is filmed and played back at 24 frames per second, while television uses 25-30 frames. High-speed film cameras can film up to a quarter of a million frames per second by running the film over a rotating prism or mirror instead of using a shutter, thus reducing the need for stopping and starting the film behind a shutter which would tear the film stock at such speeds. Using this technique one can stretch one second to more than ten minutes of playback time (super slow motion).
High-speed cameras are frequently used in science in order to characterize events which happen too fast for traditional film speeds, i.e. the vocal folds vibrations.
In December 2012 Julian McGlashan and Cathrine Sadolin performed an endoscopy/high speed study at CVI in Copenhagen. We recorded 9 singers using highspeed technology. Each singer was examined using an high-speed digital camera:
- Photron Fastcam MH4
– 512X256 resolution
– Captures 8s B&W footage
– 4G Internal memory, download via USB 3
- 300W Xenon light
- Rigid laryngoscope
- Simultaneous Acoustic and ELG recordings
Laryngograph electrodes were positioned over the thyroid cartilages and an omnidirectional microphone placed at distance from the singer which allowed recordings at all levels of loudness. Also the ELG and acoustic signals were captured and analysed with the Speech Studio (Laryngograph) software program.
The longest high speed recording we made lasted 3-4 seconds and it takes around 17 minutes to play back.
High speed of Vocal Breaks
Here you see a highspeed videoclip of a male singer singing Vocal breaks between Overdrive and Neutral. The singers starts in Neutral and breaks to Overdrive.
You can see the progressive narrowing of the supra glottis structure with the modes.
Notice the laryngeal gestures in Neutral. There is no gap between the vocal folds, and you can see that the posterior pharyngeal wall behind the larynx and hypopharynx is relaxed leaving the area open. The vocal folds can be seen easily as the false cords are retracted and the aryepiglottic folds are stretched more so they become thinner creating a funnel shape which is slightly steep.
Also notice the laryngeal gestures for Overdrive. The front and the back of the laryngeal opening approach each other, making the opening of the larynx more narrowed and the cuneiforms are rolled in much more than in Neutral.
In Overdrive the front and the back of the laryngeal opening approach each other, making the opening of the larynx much more narrowed and creating a more acute angle between the arytenoids and the aryepiglottic fold, and also an angle between the aryepiglottic fold and epiglottis. The cuneiforms are rolled in.
In the transition between the two settings for the modes you see the flageolet setting. where the back of the vocal folds are splinted apart allowing the mid to front part of the vocal folds to vibrating.