Kargyraa and meditation
Chen-Gia Tsai
Pipe model of a Kargyraa singer's vocal tract
The
melody pitch f1 (the centre frequency of the first formant) in Kargyraa voices
is determined by the mouth opening. A perturbation method predicts the
resonance shift caused by a bore enlargement at a position x0 of a pipe with an
irregular geometry (e.g., Fletcher & Rossing 1991). During a performance of
Kargyraa, the bore diameter of the vocal tract changes at the lips, a pressure
node for all modes. Hence, an enlargement of mouth opening leads to an increase
in the centre frequencies of the first and 
second
formants (Tsai 2001).
Figure: (a) Spectrogram of a
Kargyraa song "the far side of a dry riverbed" (b) and (c) are two
snapshot spectra of (a). They show f2=2f1.
This
pipe model does not predict (1) the small bandwidth of the first and second
formants, and (2) "mode-locking" f2=2f1. I hypothesize that periodic
vorticity bursts at the diffuser-like supraglottal structures are responsible
for producing the strong components at f1 and 2f1.
Subharmonic generation
In
Kargyraa, there is a nonlinear coupling between the two pairs of the vocal
folds, which can lead to either entrainments or chaos. While 1:2 entrainment
can produce beautiful voices of Kargyraa, pathological voices with the
involvement of chaotic vibration of the ventricular folds have a hoarse quality
(ventricular dysphonia).
Based
on recordings of high-speed images of the laryngeal movement, Lindestad and
colleagues (2001) reported that during Kargyraa singing the ventricular folds
vibrated with complete but short closures at half the frequency of the true
vocal folds, thus contributing to subharmonic generation.
Autonomic functions
It
seems that stiffness of the ventricular folds cannot be manipulated by will,
because they contain very few muscle fibres. However, the constantly increased
ventricular function and repetitive closure may lead to new functional and
anatomical changes in the interior of the larynx (such as ventricular hypertrophy)
and, possibly, to a new system of innervation.
On
the other hand, evidence of psycho emotional, cerebella or midbrain (e.g., Parkinsonism)
types of ventricular dysphonia suggests sub-cortical influences of the
ventricular folds.
It
is interesting to note that Tibetan monks do not practice their vocalization.
They improve the control of the ventricular folds through meditation! Meditation
is a conscious mental process that induces a set of integrated physiologic
changes termed the relaxation response. The elastic property of the ventricular
folds may be affected by meditation through autonomic functions. They become so
relaxed that they vibrate with complete closures at half the frequency of the
true vocal folds. In contrast, emotional stress can lead to adduction and
vibration of the stiff ventricular folds with incomplete closures. Because
lower subharmonics are weak in such melancholic voices, they sound rough.
Tibetan
monks stated repeatedly that while singing overtones one should always make a
special effort to attune heart and mind to the meaning of the holy moment
(Smith and Stevens 1967).
An
overtone singer and researcher related the psychological mechanism underlying
overtone singing during meditation to "a higher sound awareness": When
we meditate by way of singing the need to make pleasant or even beautiful
sounds moves to the background. It is not the singing that decides whether we
enter a truly meditative state of mind. More important is that we listen to ourselves
that we search for the voice inside. We are not concerned with personal
judgments about our voice or with the personality in our voice. Singing harmonics
automatically focuses the mind more than most other types of singing, because
we essentially sing just one tone and listen to its internal dynamics.
Overtones demand from us a higher than normal sounds awareness. They fulfil a
service in certain spiritual traditions and have a built-in symbolic
association with 'thing high'. They have the exceptional ability to unite
voices to the highest degree and a tendency to unify the body and the mind.
(van Tongeren 2002:207)
It
is my hypothesis that overtone singing focuses the mind automatically on the
weak pitch of the prominent nth harmonic. This form of meditation is designed
to lead one to a subjective experience of absorption with the object of focus.
From a viewpoint of neuroscience it seems appropriate that a model for this kind
of meditation begins with activation of the prefrontal cortex and the cingulated
gyrus. Brain imaging studies have suggested that tasks requiring sustained
attention are initiated via activity in the prefrontal cortex, particularly in
the right hemisphere, and the cingulated gyrus appears to be involved in
focusing attention. In an excellent review paper on the neural basis of
meditation, Newberg and Iversen (2003) proposed a neurophysiological network
possibly underlying meditative states. They discussed the prefrontal cortex
effects on thalamic activation, posterior superior parietal lobule
deafferentation, hippocampal and amygdalar activation, hypothalamic and
autonomic nervous system changes, autonomic-cortical activity, and
neurotransmitter activity. Although their model may provide a general framework
for studying the neural basis of meditation, it should be noted that there are
categories and subcategories of meditation that may be associated with
different neural activity. For example, overtone singing by Tibetan monks
belongs to the meditation category in which the subjects focus their attention
on a particular object. When the object is the melody composed of overtones,
the mental task and thus neural activity may differ from the meditation technique
that focuses the mind on an image, phrase, or word, because of the involvement
of supraglottal structures.
Nitric oxide mechanisms
Nonadrenergic, noncholinergic
(NANC) nerves, which 
cause
relaxation of airway smooth muscle, have been described in several species
including man. Nitric oxide appears to account for all the NANC response in
human central and peripheral airways in vitro. A recent review on meditation
stressed the importance of the involvement of nitric oxide during meditation
(Esch et al. 2004, see also Kim et al. 2005). Based on these findings I propose
a model for Tibetan overtone chanting:
The loop underlying Tibetan
overtone chanting can be described as: (1) a monk adducts and relaxes the
ventricular folds; (2) he sings overtones; (3) he focuses his mind on the weak
pitch of reinforced overtones; (4) this concentration triggers autonomic
functions and nitric oxide mechanisms that in turn lead to a relaxation of the
smooth muscles in the supraglottal structures.
References
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