Re: National differences in the tritone paradox (at)

Subject: Re: National differences in the tritone paradox
From:    at <parncuttSOUND.MUSIC.MCGILL.CA>
Date:    Sat, 30 Oct 1993 01:26:35 EDT

The saga continued: How to explain variations in the main pitch of an
OCT as a function of language or dialect?

The main pitch of an OCT, according to TSS82, is the most salient of
a set of virtual pitches. The salience of each virtual pitch depends
on the saliences of spectral pitches that are quasi-harmonics of that
virtual pitch. The salience of those spectral pitches in turn depends
on their absolute frequency: Spectral pitches falling in a specific
range, called the spectral dominance region, tend to be more salient,
or tend to have more influence on virtual pitches, than do pitches
outside that range.


The spectral dominance region is formulated in TSS82 by a "spectral
frequency weight" -- a mound-shaped function that is symmetrical wrt
log frequency, with a broad peak at 700 Hz. The function reflects the
average relative perceptual importance of partials of speech vowels,
as a function of their frequency.

The spectral frequency weight function, like just about everything
else in TSS82 (and most of psychophysics, for that matter) is an
AVERAGE that applies APPROXIMATELY to a given population of
listeners. An intriguing possibility is that the exact center and/or
shape of this function may depend on dialect or language. It is clear
that the timbre, and hence spectral envelope, of specific vowels
differs from one accent, dialect, or language to another. For
example, an American "oh" is timbrally deeper than an English "oh",
suggesting that the American "oh" has a lower centroid frequency.
Might American vowels be generally (or, at least, on average)
"timbrally deeper" than English ones? Has anyone measured long-time
average spectra of the speech of different languages and dialects to
find out if there are consistent differences in the distributions?


If such differences exist, then the shape and center of the spectral
dominance region in TSS82 may vary as a function of language or
dialect. That could explain variations in the pitch distribution of
OCTs, and thereby explain the observed variations in the "tritone
paradox" phenomenon.

Richard Parncutt