Acoustic distance effect on the perception of sibilants mergers between retroflexes and alveolars in Taiwan Mandarin

Abstract

Studies in speech production and perception have found a tight link between the two processes. Sound properties in speakers' production repertoire strongly influence their perceptual spaceand exposure to another variant also shifts speech patterns in shadowing tasks. This suggests that diachronic sound change might be a result of it. Therefore, we tested whether categorical perception of sibilants is influenced by acoustic distance in the production of ongoing sibilants mergers in Taiwan Mandarin, where retroflexes are merging towards alveolars. Twenty-three native speakers produced 46 mono- or disyllabic Tone 1 words with onsets of /ts/, /ʈʂ/, /tsh/, /ʈʂh/, /s/, and /ʂ/, listened to 23 eight-step continuums of synthesized sibilants from retroflexes to alveolars pre-appended to vowels and codas, and answered a sociolinguistic questionnaire. As predicted, closer acoustic distances between categories predicted more high-CoG stimuli to be identified as retroflexes (more tolerance for high-frequency retroflexes). Step, sound, and social effects were significant. Sibilants' frequencies were lower than previously reported. Overall, this suggests that sibilant mergers diffuse to speakers with closer acoustic distances first, and the categories will collapse on language level in production before perception. They spread among speakers asynchronously and variably, depending on dialectal background and social attitude as well.