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
The sound changes from Neutral without air to Overdrive
In the video example below notice the non metallic soft and airy character of the sound in Neutral with air, changing to the loud, shout-like full metallic character of the sound in Overdrive.
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 Overdrive
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 even more.
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 Overdrive
The laryngograph waveform in Overdrive shows a steep onset and a fairly long closure of the vocal folds and sometimes a roll off with a little knee. The steep onset indicates that the vocal folds are coming together very rapidly and stay together for longer, so they are more closed than open during the vibratory cycle, which corresponds nicely with the loud volume often used in Overdrive.
This video is a male singing on a sustained single note (C3, 260 Hz) on the vowel EH (as in ‘stay’) in Overdrive and on EE (as in ‘see’) in Neutral with air, alternating back and forth.
Alternating between Neutral without air and Overdrive
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
The sound changes from Neutral without air to Overdrive
In the video example below notice the non metallic and ‘clear’ character of the sound in Neutral without air, changing to the loud, shout-like full metallic character of the sound in Overdrive.
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 Overdrive
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 even more.
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 Overdrive
The laryngograph waveform in Overdrive shows a steep onset and a fairly long closure of the vocal folds and sometimes a roll off with a little knee. The steep onset indicates that the vocal folds are coming together very rapidly and stay together for longer, so they are more closed than open during the vibratory cycle, which corresponds nicely with the loud volume often used in Overdrive.
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 Overdrive, alternating 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.