Simultaneous Articulatory and Acoustic Distortion in L1 and L2 Listening: Locally Time-Reversed "Fast" Speech

The current study explores how native and non-native speakers cope with simultaneous articulatory and acoustic distortion in speech perception. The articulatory distortion was generated by asking a speaker to articulate target speech as fast as possible (fast speech). The acoustic distortion was created by dividing speech signals into small segments with equal time duration (e.g., 50 ms) from the onset of speech, and flipping every segment on a temporal axis, and putting them back together (locally time-reversed speech). This study explored how “locally time-reversed fast speech” was intelligible as compared to “locally time-reversed normal speech” measured in Ishida, Samuel, and Arai (2016). Participants were native English speakers and native Japanese speakers who spoke English as a second language. They listened to English words and pseudowords that contained a lot of stop consonants. These items were spoken fast and locally time-reversed at every 10, 20, 30, 40, 50, or 60 ms. In general, “locally time-reversed fast speech” became gradually unintelligible as the length of reversed segments increased. Native speakers generally understood locally time-reversed fast spoken words well but not pseudowords, while non-native speakers hardly understood both words and pseudowords. Language proficiency strongly supported the perceptual restoration of locally time-reversed fast speech.