In June 2007, 2012 and 2014 Julian McGlashan and Cathrine Sadolin performed endoscopy studies and endoscopy/high speed studies in 2012 and 2014 at CVI in Copenhagen.
Twenty-one singers (ten males and eleven females) in 2007, thirteen singers (seven male and six females) in 2012, and sixteen singers (seven males and nine females) in 2014, a total of 32 singers (fifteen male and seventeen females), trained in the Complete Vocal Technique were recruited and asked to produce a sustained vowel in each of the four modes and then adding twang to that that mode. Subsequently they were asked to alternate between the ‘clear’ mode and the mode with twang.
10 subjects had pictures that we could analyse for this particular study, so the rest were excluded as they could either not tolerate the examination, did not perform the twang correctly, or the image quality was not adequate for interpretation.
Each singer was examined using an OTVS7 camera (Olympus) and ENFV2 videoscope (Keymed) coupled to the Laryngostrobe (Laryngograph) digital capture system. 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.
Each set of modes (with and without twang) video images were analysed by Julian McGlashan and Cathrine Sadolin and the appearance and relationship between the key anatomical features was agreed by consensus and documented. The consistent features were identified and descriptive and explanatory text to aid pattern recognition.
The Laryngeal gestures are more to be seen as patterns of progression from mode to mode, rather than aboslutes. The progession in the patterns can be used as guidelines on how to identify the modes within each singer.
For the twang these are the parameters we looked at: the shape of the glottis, the position of the false cords, the anterior posterior narrowing, the shape of the pirriforma fossa, the hight of the larynx, the pharyngeal wall, the epiglottis and the arytenoid/cuneiform complex.
Not only did we look at what was changing between using the mode and the mode with twang, we also looked at what was actually vibrating.
To get a better understanding of the laryngeal changes associated with twang and to examine the interaction of supraglottic vibration during intentional twang and vocal fold vibration.
We gave the various parts in the vocal tract levels in order to identify and specify on which levels the various changes take place. The levels also make it easier to communicate where the changes take place. On the videos from the footage only the first 3-4 levels are seen. For more info on the level, click here.
When we look at the video examples of the mode with and without twang we see that when twanging, the opening of the epiglottic funnel is made smaller by bringing the arytenoid cartilages closer to the lower part of epiglottis (the petiole). The singer can vary the degree of twang. Some twang is called ‘necessary twang’ and when the opening of the epiglottis funnel is made even smaller by bringing the epiglottis even closer to the arytenoid cartilages, the sound assumes a sharper and more penetrating, snarling character, like a cackle. This is known as ‘distinct twang’.
Twang can be done safely.
Notice that the waveform of the vocal mode is maintained during the twang. This indicates that the vibrations of the vocal folds are unhindered and unaffected by the twang. So the vocal folds are vibrating freely under the twang. This makes sense because the we know that the twang is taking place higher in the vocal tract and not on the 1st level (the level of the vocal folds).
In all the examples where we can see the vocal folds, or look at the laryngograph trace, there seems to be a resonably regular pattern, and there didn’t appear to be any evidence of the effect (or any additional noises) being produced in the vocal fold level.
There was evidence on endoscopy or from the Laryngograph of periodic vocal fold vibration.
It need a good technique to ensure accurate vocal mode setting done correctly and an intentional application of the effect.
This information has not yet been presented.