In the video example below notice the change of the character of the sound, the change in visual laryngeal appearance, and the change in visual laryngograph waveform appearance when the singer changes back and forth between the notes/modes.
The sound changes from Neutral without air to Edge
In the video example below notice the non metallic and ‘clear’ character of the sound in Neutral without air, changing to the loud, scream-like full metallic character of the sound in Edge.
The visual laryngeal appearance
The laryngeal gestures changes from Neutral without air
In Neutral without air you can see that there is no gap between the vocal folds. Be aware that when a rigid scope with stroboscopy is used it may sometimes look like there is a gap between the folds, but this is only visible posteriorly and at certain points in the vibratory cycle. To distinguish Neutral with air from Neutral without air first check to see if a gap can be identified (level 1). In Neutral without air and Neutral with air 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 and tensed so they become thinner creating a funnel shape which is slightly steeper in Neutral without air than in Neutral with air.
The laryngeal gestures changes to 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 more acute angle between the arytenoids and the aryepiglottic fold and also an 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 visual laryngograph waveform appearance
The laryngograph waveform changes from Neutral without air
The Neutral without air laryngograph waveform shows a shallower upward (closing) and downward (opening) curve compared to the sinusoidal waveform with occasional spike seen in Neutral with air. This corespond nicely with the louder volume often used in Neutral without air compared to Neutral with air. When compared to the metallic modes, the waveform is frequently bell shaped and symmetrical and the overall contact time is reduced which means that the gaps (when the vocal folds are apart) are shorter.
The laryngograph waveform changes to Edge
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.
This video is a male singing on a sustained single note (C3, 260 Hz) on the vowel EH (as in ‘stay’) in Edge and on EE (as in ‘see’) in Neutral without air, alternating back and forth.
This video is a female singing on a sustained single note (B4, 480 Hz) on the vowel EE (as in ‘see’) in Neutral without air and on EH (as in ‘stay’) in Edge, alternating back and forth. The electrodes of the Laryngograph did not pick up the correct signal so the waveform looks weird.
These videos are from the endoscopy study performed by Julian McGlashan and Cathrine Sadolin at CVI in Copenhagen in June 2007. This study has not yet been presented.