||Perception of vowels and consonants: From acoustic diversity to cognitive isotropy
The aim of this paper was to explore possible common points in the perception of place-of-articulation distinctions between stop consonants, on one hand, and between French closed vowels, on the other. Place-of-articulation contrasts correspond to changes along the front-back articulatory dimension for both stops and closed vowels, the b/d/g ordering for the stops corresponding to the i/y/u ordering for the vowels. However, the acoustic consequences of front-back changes are inverted for stops and vowels: the onsets of the F2 and F3 transitions either decrease or increase with a backward articulatory change depending on the phonetic class, vowels vs. stops. Identification data were collected for /bә, dә, gә/ and /iә, yә, uә/ syllables varying along a circular continuum in the F2-F3 transition onset space. Results showed that the perceptual boundaries for vowels and consonants did not coincide in the F2-F3 acoustic space. After rotation, however, vowel and consonant boundaries almost coincided, and the articulatory correspondence between the two classes of sounds was restored. This shows that the place boundaries both between stops and between vowels are isotropic (invariant by rotation), a property which is seemingly based on the integration of the articulatory-acoustic inversion between the two classes of sounds into perceptual representations. Implications for feature theory and models of speech perception are outlined.