Role of labeling mediation in speech perception: Evidence from a voiced stop continuum perceived in different surrounding sound contexts

Abstract

The theory of categorical perception of speech sounds traditionally suggests that speech sound discrimination is conducted based on phonemic labeling, which is an abstract speech representation that listeners are hypothesized to have. However, recent research has found that the impact of labeling on perception of an English /ɹ/–/l/ contrast may depend on surrounding sound contexts: the effects of phonemic labeling may disappear when the speech sounds to be discriminated are presented in a sentence. The purpose of the present research is to investigate (1) the effects of the sound contexts on categorical perception of speech sounds, and (2) cross linguistic extensibility of such an effect. The experiments employed a Japanese voiced stop consonant continuum, i.e., /ba/–/da/, and tested discrimination of sounds on the continuum by native speakers of Japanese. Experiment 2 in particular investigated whether sounds on such a continuum are discriminated in accordance with the labeling when the sound in question is inserted into a sentence. Through experiments, the cross linguistic effects of surrounding sound contexts are found although there may be some exceptional cases. The research proposes reconsideration of the role of labeling mediation in speech perception.