Below you see a videoclip of Edge. The video was taken using a flexible endoscope inserted via the nose. Stroboscopic light is used so the vibration of the vocal folds can be seen in slow motion. The flashing of the stroboscopic light is triggered using the Laryngograph signal. This is obtained by placing two electrodes placed on the neck over the larynx and the waveform can be seen as a a green moving line at the bottom of the image. When the vocal folds are vibrating and touch each other the green line rises and when they peel apart the line falls creating the change in shape of the waveform.
In the video example below notice the loud, scream-like character of the sound and the visual appearance and waveform of Edge.
In Edge the opening of the larynx is even more narrowed, and the cuneiforms are rolled in even more than in Overdrive. This makes it hard to see the vocal folds. The narrowing creates an even sharper angle between the arytenoids and the aryepiglottic fold and also an even sharper angle between the aryepiglottic fold and epiglottis. The piriform fossae and area between the back wall (posterior pharyngeal wall) and the larynx becomes very small and is often closed off altogether. The larynx is raised to a higher position (you can see that it gets closer to the camera).
The Edge laryngograph waveform shows a steep onset and a quite long closure of the vocal folds with a gradual roll off. The steep onset indicates that the vocal folds are coming together very rapidly and stay together for longer, so they are closed much longer than they are open. This corresponds nicely with the loud volume often used in Edge.
The video below is a male singing a glissando from low pitch to high pitch returning to low pitch again on the vowel A (as in ‘and’) in Edge. Notice that the waveform stays the same through the Edge pitches – it just gets narrower as the pitch increases.