A perceptual explanation for the adaptation of aspirated stops in Indic languages

Indic languages and Indian varieties of English have an adaptation pattern whereby English aspirated stops are adapted as unaspirated, even though Indic languages have contrastive aspirates. We tested the possibility of this unexpected adaptation pattern having a perceptual explanation. Aspirated stops in English and various South Asian languages differ in their acoustic properties (Wiltshire, 2005; Wiltshire and Harnsberger, 2006). Moreover, the acoustic properties of voiceless stops in Indian varieties of English are comparable to those of Indic languages (Narkar and Staroverov, 2022). Specifically, Indic aspirated stops have longer voice onset times (VOT), and the consonant-induced f0 (Cf0) following these stops is lower in Indic languages than in English. We tested English and Hindi listeners’ perceptions of 50 tokens on the ka-kʰa continuum in a categorization task. The stimuli were resynthesized by combining 10 VOT values and 5 f0 values from the natural speech of a Marathi (Indic) speaker. Results show that English and Hindi listeners do perceive aspiration differently—English listeners’ VOT categorization boundary is lower than Hindi listeners’ and English listeners' boundary becomes lower as the f0 increases, whereas f0 has no effect on Hindi listeners' categorization boundary.