Cross-Linguistic Effects of the Speech-to-Song Illusion in Speakers of Bangla and English

The speech-to-song illusion is a phenomenon in which the continuous repetition of a spokenutterance induces the listeners to perceive it as more song-like. Thus far, this perceptualtransformation has been observed in mostly European languages, such as English; however,it is unclear whether the illusion is experienced by speakers of Bangla (Bengali), anIndo-Aryan language. The current study, therefore, investigates the illusion in 28 Bangla-and 31 English-speaking participants. The experiment consisted of a listening task inwhich participants were asked to rate their perception of repeating short speech stimuli ona scale from 1 − 5, where 1 = "sounds like speech" and 5 = "sounds like song". The stimuliwere composed of English and Bangla utterances produced by two bilingual speakers. Toaccount for possible group differences in music engagement, participants self-reportedmusical experience and also performed a rhythm discrimination task as an objectivemeasure of non-verbal auditory sequence processing. Stimulus ratings were analysed withcumulative link mixed modelling. Overall, English- and Bangla-speaking participants ratedthe stimuli similarly and, in both groups, better performance in the rhythm discriminationtask significantly predicted more song-like ratings beyond self-reported musical experience.English speakers rated Bangla stimuli as significantly more song-like than English stimuli.Bangla speakers did not distinguish between English and Bangla stimuli–possibly reflectingtheir enhanced understanding of English, in comparison to the English participants’comprehension of Bangla. An exploratory acoustic analysis revealed a role of harmonicratio in the illusion for both language groups. These results demonstrate that thespeech-to-song-illusion occurs for Bangla speakers to a similar extent as English speakersand that, across both groups, sensitivity to non-verbal auditory structure is positivelycorrelated with susceptibility to this perceptual transformation.