Relationships between phonetic perceptual and auditory spaces for fricatives
This study investigates the correlations between phonetic, perceptual and auditory spaces of fricatives. These spatial representations are constructed from estimated distances between fricatives in each domain. The present work is an extension of previous studies with vowels, which showed a close association between the auditory and perceptual spaces. The dimensions obtained were highly related to the formant frequencies of the vowels and their phonetic (articulatory) descriptions. However, these findings could have been anticipated due to inherent similarities in articulatory and acoustic forms of vowels. No corresponding relationships for consonants have yet been established, and it is important to investigate whether such relationships might also hold for consonants, since their acoustic form is not so simply linked to their phonetic (articulatory) form. In this study we relate 'places of articulation' for fricatives with their spectral characteristics and perceptual similarities to investigate any articulatory references to their perception. A variety of fricative and fricative-like stimuli were examined. Perceptual distances were derived from subjective judgments of the similarities between the fricatives. Auditory distances were obtained from critical bandpass filter banks and distance metrics were applied to model the spectral processing in the auditory periphery. The distances in the perceptual and auditory spaces were analysed using multidimensional scaling in order to test their correlation and how it varied according to the naturalness of the stimulus materials. The relations between the spaces were measured quantitatively by canonical correlation analyses. The acoustic correlates of these spatial dimensions were also identified. The perceptual dimensions of the most natural fricative stimuli proved to be highly related to both their phonetic (articulatory) and auditory spaces. By demonstrating a link across these domains, the study, therefore, favours perceptual theories of a unified nature, rather than the views based on 'strong articulatory' or 'strong auditory' modes of speech perception.