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Locus Theory (2)
• Strong Version: All consonants have a
fixed target which is realised at a single
frequency for each formant.
• The F2 target for a particular consonant is
known as its F2 locus
Syllable-based theories (1)
• There is a growing consensus that the
most important basic element of
articulatory planning is the syllable.
• In such approaches a gesture, rather than
a series of phoneme targets, is the
underlying strategy in articulatory planning
(and for some theorists, also of speech
perception).
Coarticulation and Resonance (1)
• Vocal tract articulation results in changing
vocal tract shapes that can be described
as one or more resonating cavities.
• Resonating cavities can be modelled in
terms of simple tube models (see the topic
for this subject entitled “Acoustic Theory of
Speech Production”).
Locus Theory (3)
• Weak Version: Consonants don't have a
fixed target as their targets are affected by
coarticulation, but they do tend to have a
locus space for each formant defined by a
range of formant frequencies. The target
frequency tends to be within this range
and depends upon the adjacent sound
• The weak version is supported by a vast
body of research
Syllable-based theories (2)
• In such a theory we no longer have
invariant phoneme targets (or even a
range of targets) but rather we have
patterns of articulation for each type of
syllable.
• The acoustic consequences of this
approach results in similar acoustic
predictions the weak version of the locus
theory.
Coarticulation and Resonance (2)
• Each resonating cavity (tube) has its own
set of resonance frequencies.
• Most speech articulations, with the
exception of the neutral vowel (similar, but
not identical, to Australian English /3:/)
can be simply modelled by two tubes.
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