>from Lloyd...
>It appears that you are assuming that the strength of the partial in
>the phonated sound is the only possible source of strength in the
>resonated tone.
Dear Lloyd,
Yes, but the fundamental, I suggest is the repetition rate of
closure and the all important harmonics are a function, as I imagine it,
of the closing and opening _rates_ as well as the duty cycle. Put another
way, I regard the speed of the transition from open to closed, and
closed to open, to be crucial to the production of the harmonics and
their amplitude. The duration for which the folds are closed, relative
to the duration for which they are open, is another important and
adjustable factor in the production of harmonics but NOT, of the
fundamental. For the fundamental, any duty cycle, or closure rate
will be ok, as long as the period remains the same.
> There is the physical phenomenon of an originating
>tone being amplified acoustically by a resonating chamber.
Lloyd I'm sorry, you may have missed my submission some time
ago that this is an unfortunate misconstruction of certain other
physical phenomenon. Namely, that although resonant devices
can be used to greatly enlarge signals, without careful buffering,
the act of removing energy from them, will destroy the very
characteristic we value so highly.
> Of
>course, for this to happen the energy must come from somewhere and
>the difficulty is from where? The resonating characteristic of a
>closed tube is able, if conditions are correct, to borrow (as it
>were) energy from dampened partials or partials that are not
>resonated as strongly as their original strength upon entering the
>resonating space.
We have to be careful here that we're not confusing purification by
resonating with energy translation by intermodulation. A resonant
device will normally dissipate as heat, in an external load, any signal
that does _not_ fall within its tuned bandwidth. I consider that you
correctly rejected intermodulation as a source of vocal tone some time
ago, although it's difficult to be absolute on this principle. Still, there
would be clusters of sum and difference signals surrounding the
harmonics.
> Perhaps this energy is transmuted to provide the
>increase in acoustic amplification in addition to that more naturally
>supplied by the emphasis of particular partials.
To me, transmuted is another word for intermodulation, and if we
were to accept that it occurs, _which I doubt_, the place I would be
looking would be around that 6 :1 incline, but I don't see that as the
grossly non-linear device that would be required to produce the
mixing. Maybe! And if we took all the energy the early harmonics
had to offer in the simple series, it would still be less than that of
the fundamental, and that doesn't allow for conversion losses.
I can't accept the use of the word amplification here, because it implies
active buffering of resonant cavities, and no such buffering exists
beyond the larynx. This is critical to my proposition that resonance
is used to purify and impedance match, and that the apparent
enlargement, is actually an efficiency gain in combination with the
moderation of temporal effects that enable a larger tone to be
produced.
>There is also very strong evidence to indicate that the male voice is
>incapable of producing a fundamental throughout its total range until
>it reaches the frequency of about G4 and above.
I can accept this, because of the vocal tract dimensions and their use
as part of the low frequency purification process, but I still suggest
that including consideration of the effects of the 1/4 wavelength of
the tract diminishes the problem. Apart from that processing difficulty,
I cannot imagine why there should be any problem with a closure
repetition rate at the lower frequencies, although the desirable open
fold duration, may be difficult to maintain as we go still lower.
> What we hear is the
>spectrum of partials that would normally be found with a given
>fundamental and our ears (or minds) provide the phantom fundamental.
>If this is so, then the calculations of relative strengths of the
>partials would change appreciably.
Sounds ok to me :) I have no problem with the possibilities of aural
integration of groups of high rate pulses at a lower cyclical rate.
It offers the possibility of still greater harmonic energy if that's
what we want. The calculations change drastically anyway as soon
as we move away from the idealised 50% duty cycle which was only
the starting point.
I cannot express how highly I value your input Lloyd
and I'm sure that your vast knowledge and enthusiasm
will be greatly missed following your retirement next fall.
So I wish you a happy retirement, if that's what you intend.
I am most appreciative.
Regards Reg.
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