Vocalist.org archive


From:  Sally Collyer <scol8413@m...>
Date:  Sun Apr 7, 2002  12:51 am
Subject:  Re: [vocalist] For Sally.... :)

Dear Reg

You ask for a reference in relation to my assertion that
>there is an absence of even harmonics in a square wave as
>derived during one mode of the open and closed functions of
>the cords.

No, my question was not in regard to the analysis of a square wave (but
thank you for the trouble you went to in reproducing the formulae). The
question related to your statement:

>My answer...not falsetto. Falsetto implies an almost total
>absence of ODD harmonics of the fundamental frequency.

I am interested that you see a square-waved pattern in the vocal
source. The flow glottograms I have seen of falsetto have never suggested
a square wave to me but more a waveform approaching sinusoidal. It is
unclear to me what would cause the sharp changes in the waveform essential
to the square-waved pattern: the rapid rise in flow, sharp change to
plateau, rapid drop and sharp change to either zero or perhaps negative
plateau. I also see a significant difference in the resulting (source)
spectrum: the sharp declinations in the square-waved pattern generate
greater energy in higher-lying partials, yet I have always understood
falsetto to be associated with a high drop-off in energy in the source
spectrum. I should add that my understanding (from the related experiences
of speech pathologists and from the endoscopies I have seen) is that vocal
fold closure can occur in falsetto, at rates related and unrelated the
fundamental frequency. One of your replies mentions:

>The spectrum analysis provided by this programme currently in favour

Excuse me if I have missed mention of the program, possibly in the previous
discussion which gave rise to this one, but I'm not sure to which program
you refer. Without illustration, I am possibly misunderstanding your point
completely: perhaps if you were able to send me some of the falsetto
source waveforms which you have found to approximate square waveforms, I
would understand your concepts better.

Kindest regards

Sally




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