2018 Sun Session C 0900

Sunday, November 4, 2018 | Session C, Terrace Lounge | 9am

Hypo-articulation in infant-directed speech: the case of the Nepali four-way stop voicing contrast
T. Benders, S. Pokharel, K. Demuth

Background: Hyper-articulation in infant-directed speech (IDS) compared to adult- directed speech (ADS) is often reported (Kuhl et al., 1997) and may support perceptual attunement (Liu et al., 2003). However, hyper-articulation is not cross- linguistically universal, and IDS may even be hypo-articulated in some languages (Martin et al., 2015). This raises questions about the relationship between hyper- articulation and the difficulty of the learning task that children face. If parents hyper- articulate to support perceptual attunement, hyper-articulation is predicted to occur when perceptual attunement may be challenging.

Stop voicing is no exception to the mixed results on hyper-articulation: Stop contrasts are hyper-articulated in some studies (Malsheen, 1980), which may be a side effect of speaking rate (McMurray et al., 2013), and hypo-articulated in others (Baran et al., 1977). Perceptual attunement for stop voicing may be more challenging when the phonetic space is crowded and includes contrastive prevoicing, which is not perceptually salient (Eimas et al., 1971). However, stop voicing in IDS has been documented for one system larger than two stops (Narayan & Yoon, 2011; hypo- articulation of the Korean three-way contrast), and one system with contrastive prevoicing (Fish et al., 2013; hyper-articulation in Spanish), never in a system that has both. The Nepali four-way stop voicing system is the largest attested stop consonant inventory (/ɡ, ɡʱ, k, kh/) and includes two stops with contrastive prevoicing (/ɡ, ɡʱ/; Poon & Mateer, 1985). The present study therefore investigates whether stop voicing contrasts are hyper-articulated in Nepali IDS.

Method: Word-onset /ɡ, ɡʱ, k, kh/ were elicited in target words from sixteen Nepali- speaking mothers in naturalistic interactions with their own infants (mean age: 14.1 months; IDS) and a Nepali-native experimenter (ADS). Analyses were conducted using mixed effects regression models.

Analysis & Discussion 1: IDS, compared to ADS, displayed less frequent production of prevoicing, shorter lead time (if present), and shorter lag time (Figure 1; Table 1).

The contrast between voiced and voiceless stops is thus hypo-articulated in Nepali IDS, despite the large Nepali stop voicing system with contrastive prevoicing. These results raise questions about the motivation behind hyper-articulation, when it occurs, and the acquisition of the four-way stop contrast by Nepali infants.

A critical question is what causes lead-time hypo-articulation and lag-time shortening in Nepali IDS. Answering this question may contribute to the currently poor understanding of hypo-articulation. One possibility is that consonant shortening is a side effect of vowel lengthening, a function of slow IDS speaking rate (cf. Martin et al., 2017). A second series of analyses therefore addressed the consonant/vowel trading relationship in Nepali IDS.

Analysis & Discussion 2: IDS, compared to ADS, generally displayed longer vowels and smaller consonant-to-syllable ratios (Figure 1, Table 2).

These results are the first to reveal that vowels in IDS can be lengthened at the expense of the consonant. While long vowels may enhance vowel acquisition, this may result in reduced consonant clarity. Future research should address the cross- linguistic prevalence of this register-specific consonant/vowel trading relationship and the implications for learning crowded consonant systems.

References

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