Invariants, specifiers, cues: an investigation of locus equations as information for place of articulation.

This experiment explored the information for place of articulation provided by locus equations--equations for a line relating the second formant (F2) of a vowel at midpoint of F2 of the formant at consonant-vowel (CV) syllable onset. Locus equations cue place indirectly by quantifying directly the degree of coarticulatory overlap (coarticulation resistance) between consonant and vowel. Coarticulation resistance is correlated with place. The experiment tested predictions that when coarticulation resistance varies due to properties of the consonant other than place of articulation (in particular, due to manner of articulation), locus equations would not accurately reflect consonantal place of articulation. These predictions were confirmed. In addition, discriminant analyses, using locus equation variables as classifiers, were generally unsuccessful in classifying a set of consonants representing six different places of articulation. I conclude that locus equations are unlikely to provide useful place information to listeners.