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 with air to Neutral without air
In the video example below notice the soft, airy character of the sound in Neutral with air, changing to the non metallic and ‘clear’ character of the sound in Neutral without air.
The visual laryngeal appearance
The laryngeal gestures changes from Neutral with air
Notice the visible gap between the vocal folds, which is bigger at the back. You can see that the back wall of the larynx is relaxed leaving the larynx open so you can see the vocal folds easily. You can also see the aryepiglottic fold is stretcheded and relaxed and the opening of the larynx (the laryngeal inlet) has a shape of an ‘open’ funnel which is rather wide at the top.
The laryngeal gestures changes to 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 visual laryngograph waveform appearance
The laryngograph waveform changes from Neutral with air
The Neutral with air laryngograph waveform has a sinusoidal shape. This is because there is no contact between the vocal folds due to the gap, which means that a lot of air is added to the sound and the volume is soft. In another example of Neutral with air there is the initial sinusoidal waveform but a brief upward spike indicating momentary closure of the vocal folds.
The laryngograph waveform changes to 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 first video is a male singing on a sustained single note (C3, 260 Hz) on the vowel EE (as in ‘see’) alternating from Neutral with air to Neutral without air, back and forth.
The second video is a female singing on a sustained single note (Bb4, 480 Hz) on the vowel EE (as in ‘see’) alternating from Neutral with air to Neutral without air, back and forth.
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.