Titia Benders

Native, non-native and L2 perceptual cue weighting for Dutch vowels: the case of Dutch, German, and Spanish listeners

Abstract Previous research has demonstrated that learners of English with different L1 backgrounds diverge from native speakers in their use of acoustic cues for the perception and production of vowel contrasts. This study investigated the use of two cues, i.e. , vowel spectrum and duration, for the categorization of the Dutch /aː/-/ɑ/ contrast in three groups of listeners: L1-Dutch, L1-Spanish L2-Dutch, and L1-German listeners. Three aspects of vowel contrast perception were tested: the categorical nature of the listeners’ perceptual boundary, their cue weighting, and their use of the individual cues. Experience with the Dutch language played a role in the ability to perceptually distinguish the two vowel categories: Native Dutch listeners and Spanish learners of Dutch could categorize prototypical tokens of Dutch /aː/ and /ɑ/ more reliably than L1-German listeners without experience with the Dutch language. Native Dutch listeners had the most sharply defined boundary between the two categories. The results also show that language background strongly affects vowel perception: both L1-Dutch and L1-German listeners weight vowel spectrum heavier than vowel duration, whereas L1-Spanish L2-Dutch listeners favour vowel duration. L1-German listeners’ cue weighting can be explained in terms of the cross-linguistic comparison between German and Dutch vowels. L1-Spanish L2-Dutch listeners’ results have implications for theories of second language perception.

The interrelation between acoustic context effects and available response categories in speech sound categorization

In an investigation of contextual influences on sound categorization, 64 Peruvian Spanish listeners categorized vowels on an /i/ to /e/ continuum. First, to measure the influence of the stimulus range (broad acoustic context) and the preceding stimuli (local acoustic context), listeners were presented with different subsets of the Spanish /i/-/e/ continuum in separate blocks. Second, the influence of the number of response categories was measured by presenting half of the participants with /i/ and /e/ as responses, and the other half with /i/, /e/, /a/, /o/, and /u/. The results showed that the perceptual category boundary between /i/ and /e/ shifted depending on the stimulus range and that the formant values of locally preceding items had a contrastive influence. Categorization was less susceptible to broad and local acoustic context effects, however, when listeners were presented with five rather than two response options. Vowel categorization depends not only on the acoustic properties of the target stimulus, but also on its broad and local acoustic context. The influence of such context is in turn affected by the number of internal referents that are available to the listener in a task.

Second Language Attainment and First Language Attrition: The Case of VOT in Immersed Dutch-German Late Bilinguals.

Speech of late bilinguals has frequently been described in terms of cross-linguistic influence (CLI) from the native language (L1) to the second language (L2), but CLI from the L2 to the L1 has received relatively little attention. This article addresses L2 attainment and L1 attrition in voicing systems through measures of voice onset time (VOT) in two groups of Dutch–German late bilinguals in the Netherlands. One group comprises native speakers of Dutch and the other group comprises native speakers of German, and the two groups further differ in their degree of L2 immersion. The L1-German–L2-Dutch bilinguals (N = 23) are exposed to their L2 at home and outside the home, and the L1-Dutch–L2-German bilinguals (N = 18) are only exposed to their L2 at home. We tested L2 attainment by comparing the bilinguals’ L2 to the other bilinguals’ L1, and L1 attrition by comparing the bilinguals’ L1 to Dutch monolinguals (N = 29) and German monolinguals (N = 27). Our findings indicate that complete L2 immersion may be advantageous in L2 acquisition, but at the same time it may cause L1 phonetic attrition. We discuss how the results match the predictions made by Flege’s Speech Learning Model and explore how far bilinguals’ success in acquiring L2 VOT and maintaining L1 VOT depends on the immersion context, articulatory constraints and the risk of sounding foreign accented.

An evidence accumulation model of acoustic cue weighting in vowel perception

Abstract Listeners rely on multiple acoustic cues to recognize any phoneme. The relative contribution of these cues to listeners׳ perception is typically inferred from listeners׳ categorization of sounds in a two-alternative forced-choice task. Here we advocate the use of an evidence accumulation model to analyze categorization as well as response time data from such cue weighting paradigms in terms of the processes that underlie the listeners׳ categorization. We tested 30 Dutch listeners on their categorization of speech sounds that varied between typical /ɑ/ and /aː/ in vowel quality (F1 and F2) and duration. Using the linear ballistic accumulator model, we found that the changes in spectral quality and duration lead to changes in the speed of information processing, and the effects were larger for spectral quality. In addition, for stimuli with atypical spectral information, listeners accumulate evidence faster for /ɑ/ compared to /aː/. Finally, longer durations of sounds did not produce longer estimates of perceptual encoding time. Our results demonstrate the utility of evidence accumulation models for learning about the latent processes that underlie phoneme categorization. The implications for current theory in speech perception as well as future directions for evidence accumulation models are discussed.

Heritage language exposure impacts voice onset time of Dutch–German simultaneous bilingual preschoolers

This study assesses the effects of age and language exposure on VOT production in 29 simultaneous bilingual children aged 3;7 to 5;11 who speak German as a heritage language in the Netherlands. Dutch and German have a binary voicing contrast, but the contrast is implemented with different VOT values in the two languages. The results suggest that bilingual children produce ‘voiced’ plosives similarly in their two languages, and these productions are not monolingual-like in either language. Bidirectional cross-linguistic influence between Dutch and German can explain these results. Yet, the bilinguals seemingly have two autonomous categories for Dutch and German ‘voiceless’ plosives. In German, the bilinguals’ aspiration is not monolingual-like, but bilinguals with more heritage language exposure produce more target-like aspiration. Importantly, the amount of exposure to German has no effect on the majority languages ‘voiceless’ category. This implies that more heritage language exposure is associated with more language-specific voicing systems.

Observed effects of “distributional learning” may not relate to the number of peaks. A test of “dispersion” as a confounding factor

Distributional learning of speech sounds is learning from simply being exposed to frequency distributions of speech sounds in one’s surroundings. In laboratory settings, the mechanism has been reported to be discernible already after a few minutes of exposure, in both infants and adults. These “effects of distributional training” have traditionally been attributed to the difference in the number of peaks between the experimental distribution (two peaks) and the control distribution (one or zero peaks). However, none of the earlier studies fully excluded a possibly confounding effect of the dispersion in the distributions. Additionally, some studies with a non-speech control condition did not control for a possible difference between processing speech and non-speech. The current study presents an experiment that corrects both imperfections. Spanish listeners were exposed to either a bimodal distribution encompassing the Dutch contrast /ɑ/∼/a/ or a unimodal distribution with the same dispersion. Before and after training, their accuracy of categorization of [ɑ]- and [a]-tokens was measured. A traditionally calculated p-value showed no significant difference in categorization improvement between bimodally and unimodally trained participants. Because of this null result, a Bayesian method was used to assess the odds in favor of the null hypothesis. Four different Bayes factors, each calculated on a different belief in the truth value of previously found effect sizes, indicated the absence of a difference between bimodally and unimodally trained participants. The implication is that “effects of distributional training” observed in the lab are not induced by the number of peaks in the distributions.