Dear Reg and Vocalisters:
>Sally I understand your problem with inertance but while I try
>and see it from where you do, I have a problem with giving it
>a very serious impact on the cords as long as the tuning of
>the tract is in sympathy with the current operation of the cords.
>
>Different story if they are not tuned.
COMMENT: May I refer you to an excellent discussion of inertance and
its effects on the vocal folds in Titze's book "Principles of Voice
Production" His research indicates strongly that the inertia of the
air column in BOTH the supra and sub glottal area provides a load on
the vocal folds that is necessary for continuation of vocal folds
oscillation. His book also does a good job of explaining Fourier
analysis of sound waves and its use in voice research.
>Another way, the cords are an integral oscillating group,
>as such they are presenting a signal to the tract which is
>sourced from a generator whose source impedance is NOT
>legitimately an impedance, but a dynamic resistance. Non-
>reactive. As long as the LOAD is totally resistive, as it reflects
>to the "generator," it will NOT upset the conditions in the
>generator which will then have MINIMUM energy drawn from
>it and thus its flywheel condition will remain stable needing
>almost ZERO energy replenishment from the lungs.
>Such a condition is just what we all seek with varying
>degrees of success.
COMMENT: "A dynamic resistance." But "Non-reactive"? If the load
is "totally resistive" aerodynamically it WILL affect the oscillation
of the vocal folds. Such may not be true of electrical processes
such as a "generator" with source "impedance" that is in reality a
dynamic "resistance", but it is true of aerodynamic processes. I
have nothing to indicate that what applies to one field will apply,
wholesale, to another. As mentioned above, the inertance of the
vocal tract is a necessary source of resistance energy to maintain
the continuous oscillation of the vocal folds; vocal fold elasticity
and the action of the Bernoulli Principle, of themselves, is not
sufficient.
>I'm not at all surprised that you see only sinusoidal content
>in falsetto but have you seen anything that enables you to
>distinguish the light head voice from the falsetto, despite the
>similar quality, for quality, or harmonics, is where I would expect
>to see the difference, even if only slight?
COMMENT: Quite right. The quality of tone which in turn reflects
its harmonic content is where one can see the difference between
falsetto and forms of head voice. The included action of the
thyroarytenoid muscles in head voice provides the primary difference
between it and falsetto. A supported falsetto is believed to be a
falsetto in which the there is some closure of the folds, that is,
some adduction, but the thyroarytenoid muscles are not active. In
head voice, thyroarytenoid muscle activity is present; the degree of
activity determines the intensity of the head voice.
--
Lloyd W. Hanson
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