THE MAPPING FROM ACOUSTIC STRUCTURE TO THE PHONETIC CATEGORIES OF SPEECH - THE INVARIANCE PROBLEM - OPEN PEER COMMENTARY

This commentary focuses on the nature of combinatorial properties for speech and the locus equation. The presence of some overlap in locus e quation space suggests that this higher order property may not be stri ctly invariant and may require other cues or properties for the percep tion of place of articulation. Moreover, combinatorial analysis in two -dimensional space and the resultant linearity appear to have a ''spec ial'' status in the development of this theoretical framework. However , place of articulation is only one of many phonetic dimensions in lan guage. It is suggested that a multidimensional space including pattern s derived in the frequency, amplitude, and time domains will be needed to characterize the phonetic categories of speech, and that although the derived properties ultimately may not meet the conditions of linea rity, they will reflect a higher order acoustic invariance.