Auditory representations and phonological illusions: A linguist’s perspective on the neuropsychological bases of speech perception

This paper argues that speech perception includes grammatical—in particular phonological—computations implemented by an analysis-by-synthesis component (Halle & Stevens, 1962) which analyzes linguistic material by synthesizing it anew. Analysis-by-synthesis, however, is not always required in perception but only when the listener wants to be certain that the words or morphemes identified in the input signal correspond to those intended by the speaker who produced the signal (= parity requirements, see Liberman, 1996 and Liberman and Whalen, 2000). As we will see, in some situation analysis-by-synthesis may generate ‘phonological’ illusions. A central assumption is that the representations of words or morphemes in perception involve distinctive features and are formally structured into syllables. Two perceptual modes are needed: phonetic and phonemic perception. In phonemic perception only contrastive aspects of sounds, i.e., the aspect of sounds associated with meaning differences, are searched for. In phonetic perception both contrastive and noncontrastive aspects of sounds are identified. The phenomenon of phonological ‘deafening’ will be shown to follow from phonemic perception.The paper also argues that the perception system must include an echoic memory component (Neisser (1967)) where faithful auditory representations of acoustic inputs can be stored. This echoic memory is part of a bottom-up system of perception dedicated to the collection and storage of the acoustic signal.The paper ends with the discussion of some hypotheses (and related questions) on the neural bases of perceptual processes and representations. A brief assessment of the role of mirror neurons in perception is given here.

► Speech perception includes a component that analyzes inputs by synthesizing them anew.
► This component implements computations that may generate ‘grammatical’ illusions.
► There must also be a system storing faithful auditory representations of inputs.
► There is a perceptual mode where only contrastive aspects of sounds are searched for.
► But there is also a perceptual mode where all aspects of sounds are identified.