The Speech-to-Song Illusion Is Reduced in Speakers of Tonal (vs. Non-Tonal) Languages

Abstract

The speech-to-song illusion has attracted interest as a probe of the perceptual interface between language and music. One might anticipate differential speech-to-song effects in tonal vs. non-tonal languages, since these language classes differ importantly in the linguistic value they assign to tones. Here we addressed this issue for the first time in a cohort of 20 healthy younger adults whose native language was either tonal (Thai, Mandarin) or non-tonal (German, Italian) and all of whom were also fluent in English. All participants were assessed using a protocol designed to induce the speech-to-song illusion on speech excerpts presented in each of the five study languages. Over the combined participant group, there was evidence of a speech-to-song illusion effect for all language stimuli and the extent to which individual participants rated stimuli as "song-like" at baseline was significantly positively correlated with the strength of the speech-to-song effect. However, tonal and non-tonal language stimuli elicited comparable speech-to-song effects and no acoustic language parameter was found to predict the effect. Examining the effect of the listener's native language, tonal language native speakers experienced significantly weaker speech-to-song effects than non-tonal native speakers across languages. Both non-tonal native language and inability to understand the stimulus language significantly predicted the speech-to-song illusion. These findings together suggest that relative propensity to perceive prosodic structures as inherently linguistic vs. musical may modulate the speech-to-song illusion.

Keywords: bilingual; music; prosody; speech-to-song illusion; tonal language.

Figure 1

Language excerpts used as target stimuli. IPA, International Phonetic Alphabet. Source text passages were as follows: English, the Grandfather passage (https://www.d.umn.edu/~cspiller/readingpassages.html); German, the Nordwind und Sonne passage (http://www2.ims.uni-stuttgart.de/sgtutorial/nordwind.html); Italian, passage from Giacomo di cristallo (http://www.sestogiorno.it/racconti/GiacomodicristalloRodari.pdf); Mandarin, passage created by Yu Ting Huang based on sentences used in Chinese speech therapy practice to expose speech errors; Thai, passage from Sindermsuk (1986).

Figure 2

Mean speech-to-song effect ratings for target stimuli baseline and test phase, for each stimulus language. Results for the combined participant group are shown (note data for Thai and Mandarin superimposed) see also Table 2.

Figure 3

Mean speech-to-song effect ratings for target stimuli baseline and test phase, for each native language participant group. Results for all target stimuli combined across languages are shown see also Table 3.

Figure 4

Rating scores in baseline phase and speech-to-song illusion rating for individual participants. Data are presented for target excerpts in each stimulus language. Individual speakers coded by native language as follows: G, German; I, Italian; T, Thai; M, Mandarin. Absent bars indicate zero ratings/zero change in rating.