|From:||Mark Jones <markjjones@...>|
|Date:||Thursday, April 14, 2005, 11:40|
nasalised fricatives are a tricky point, phonetically and phonologically (by
which I don't just mean their abstract feature specification: [+cons]
[+cont] [+nasal] is easy enough to write, but in some treatments that could
be just a plain nasal).
Nasalised fricatives are hard to produce. Venting the airflow through the
nasal cavity reduces the oral pressure required to create turbulence. You
can do it, but just see how much more breath force you need for a good [s],
and how sooner you run out of breath producing a sustained nasalised
fricative than its non-nasalised counterpart.
At the same time, nasalisation adds little or nothing acoustically to
voiceless fricatives, in which the sound is generated forward of the oral
constriction, with at very best weak acoustic coupling to the posterior
cavities. You might get a weak fricative, but that is down to reduction in
oral pressure and could be achieved some other way.
Nasalisation can add more acoustically to voiced fricatives, as the voicing
source at the larynx obviously excites the nasal cavity too.
BUT aerodynamically, voiced fricatives are hard enough, as the airflow
required for turbulence is lessened by driving the vocal folds, and in
voiced nasalised fricatives you now have two other systems reducing the
pressure drop across the oral constriction required for the fricative.
Result - very often an approximant.
See the discussion in the indispensable Ladefoged and Maddieson, Sounds of
the World's Languages, Blackwells, 1996: 132-134.
On the subject of nasal (rather than nasalised) fricatives, its arguably
impossible to control sphinctering of the soft palate to the extent that you
can control the generation of frication at the velum itself. Snoring can be
an ingressive nasal trill or fricative, but the mouth is usually open too,
of course. Voiceless nasals are sometimes termed 'nareal fricatives' as the
real sound generation is at the nostrils.
Mark J. Jones
Department of Linguistics
University of Cambridge