PAS-Conference October 3-5, 2002

Already before the conference starts we have questions for the faculty!

Four questions from a singer / engineer (Wim Ritzerfeld, Eindhoven, the Netherlands) to be solved in the conference:

1      Mechanical register events

In many theories about registration, only two types of muscles are held responsible for the change from the heavy mode of vibration (“chest voice”) to the light mode of vibration (“falsetto”) and vice versa: the TA (vocalis) and the CT (crico-thyroid), where the dominance of  either of the two muscles determines the register. It is also postulated by many authors that a gradual transition is possible between heavy mode and light mode. 

Other research seems to suggest that such a gradual transition between modes of vibration is not possible, although the fact is acknowledged that some voice types are able to perform a transition that is at least not detectable by ear. 

Questions:

1. Is a gradual transition between heavy and light mode possible or not ?
2. If so, is ‘voix mixte’ an example of the mix of two modes, which apparently is only possible at low intensities ?
3. If not, what does the singer do to switch to the other vibrational pattern ?
4. If not, can the TA and CT muscles be the only muscles involved or do the lateral CA and/or the interarytenoids, which both are important to achieve glottal closure, play a role as well ?

Answers:

1. The heavy and light of vibration coorespond to tow of the natural modes of vibration (eigenmodes) of the vocal folds. Although these modes van sometimes be present at the same time (generally at two different pitches), it seems highly improbable that a gradual transition between them is possible on the same pitch (see presentaion by Jan Švec).
2. 'Miced voice' is not a mixture of the two modes. Either heavy or light mode is used and the intensity is low. This low intensity makes the two kinds of 'mixed voice' hard to distinguish. However, by letting the subject make a crescendo to forte, one can always detect which mode was used (by ear as well by EGG). (See presentation by Michèle Castellengo). When singing pedagogues talk about a gradual transition between the registers they are not talking about modes of vibration, but about balancing muscle groups. This explains why these two views seem contradictionary, though in fact they are not. (See presenentations by Stephen Austin and Paul Kiesgen).
3. A jump between different patterns of vibrations i possible with almost no change in tenstions or lengths of the vocal muscles. A differnce between the two modes, however, lies in the fact that in light mode, subglottal pressure is generally lower than in heavy mode and also the closed quotient is lower ('support' ?), the singer can make sure that he/she stays within the same register.

2      Appoggio

One of the least understood areas related to the singing voice seems to be the subject of  breath support or appoggio. Definitions of appoggio are manifold and the only thing which they seem to have in common is vagueness. The main question therefore relates to the scientific description of what happens when a singer sings with appoggio. 

Questions:

1. What exactly happens on a physical level when a singer sings with appoggio ?
   Possibilities (exclusive or in combination):
   1. The muscles of inhalation and the muscles of exhalation are in balanced antagonism, thereby enabling instantaneous and accurate control of breath pressure.
   2. There is a closed loop control system in place which at all times matches breath pressure and glottal resistance to produce an optimal sound at the desired pitch and intensity
   3. The strap musculature of the larynx assumes a configuration which enables the vocal muscles to function optimally, i.e. it keeps the larynx in a comfortably low position , while the elevator muscles relax. This configuration is possibly enabled by reflexes which are related to the breathing muscles (see question nr. 2).
   4. There is a proper dynamic balance between the TA and CT muscles, thus preventing the possible overuse of other muscles such as the lateral CA or the external elevator muscles. This balance could also be aided by reflexes which are related to the breathing muscles (see question nr. 2).

There is a reflexory relationship between the breathing apparatus and the intrinsic and extrinsic laryngeal muscles. This reflexory relationship suggests the theoretical possibility that breath support has little to do with controlling the breath itself, but rather with configuring the breathing apparatus in such a way that the right reflexes are generated on the laryngeal level (see a. and d. above). This idea has been suggested by Husler and Rodd-Marling in 1965. Has this possibility ever been seriously investigated ?

Answers:

1. Points a through c seem to be true. There seems to be a lot of controversy about the 'low larynx', however. According to some people it's possible to sing with a high larynx and no substantial 'tension'. The connection between tension and high larynx could very well be habitial (Sundberg).
2. Thsi idea has been confirmed by several speakers (see e.g. Janice Chapman's presentation on 'Primal sounds'). Though the presentation by Peter Watson neatly sums up how the breathing apparatus works on a mechanical level (recommended reading for anyone who thinks he knows about the breath !), we are nowhere near an explanation of these 'primal' connections, since they involve what some people called 'hardwired circuits' in the human brain. More research in this area is definitely needed.
3. The presentation by Peter Watson neatly sums up how the breathing apparatus works.

3      Low larynx 

It is a known fact that the extrinsic musculature of the larynx and the (related) vertical position of the larynx can interfere with the operation of the TA and CT muscles. It seems that the ‘comfortably low’ position of the larynx, as it is advocated by classical pedagogy, minimises this interference. In fact the ability to minimise the interference of the extrinsic musculature is considered by many to be the hallmark of classical technique. Nevertheless I have never seen a proper explanation of the relation between larynx position, extrinsic muscle tensions and the configuration of the vocal musculature.

Question:

What is the relationship between larynx position and freedom of vocal function and how can this be explained ?

Answers:

There seems to be no consencus on this subject (see above by Appoggio)

4      Real-time feedback in the voice studio

Real-time feedback can be a powerful tool in the voice studio. Using a PC and spectrogram software (like VoceVista Audio) it has become quite easy to watch acoustical register events on the computer screen and the display can be used for real-time feedback. Events at the voice source are much harder to observe, however. The EGG is a step in the right direction, yet the information the EGG supplies is difficult to interpret for a non-specialist. It seems that either better non-invasive methods are needed to be able to generate bio-feedback related to the voice source or, alternatively, digital processing of the EGG could be performed to produce a real-time readout of e.g. the closed quotient or the mode of vibration.

Question:

1. Are there any other known non-invasive methods available ?
2. If  not, can the EGG be processed digitally to achieve real-time feedback of the closed quotient or, possibly, of the mode of vibration ?

Answers:

1. Yes, though they are not related to the voice source but to the breath. (see a.o. Lorraine Manz's presentation)
2. With the new version of VoceVista it is possible to produce a real time readout of the closed quotient. Also some more advanced methods are available to post-process the audio data (see Gregory Wakefield's presentation).