Articulatory events are imitated under rapid shadowing

Articulatory Insights into the L2 Acquisition of English-/l/ Allophony

In many English varieties, /l/ is produced differently in onsets and codas. Compared with "light" syllable-initial realizations, "dark" syllable-final variants involve reduced tongue tip-alveolar ridge contact and a raised/retracted tongue dorsum. We investigate whether native French and Spanish speakers whose L1 lacks such positionally conditioned variation can acquire English-/l/ allophony, testing the hypotheses that (1) the allophonic pattern will be acquired by both groups but (2) learners will differ from native speakers in their phonetic implementation, particularly in codas; and (3) French-speaking learners will outperform their Spanish-speaking counterparts. The production of syllable-initial and -final /l/ (singletons and clusters) in words read in isolation and a carrier sentence by 4 French- and 3 Spanish-speaking learners as well as three native English speakers was analyzed via electropalatography and acoustic analysis. While some learners produced distinct onset and coda variants and all learners had moved away to some extent from their L1 production, they differed from the native speakers in certain ways. Moreover, between- and within-group variability was observed including greater target-like anterior and posterior contact reduction in codas in the L1 French versus L1 Spanish group and generally higher F2 values in both learner groups compared with their native speaker peers. A comparison of the learners' L1 and L2 production revealed L1-based patterns of positional reduction of the tongue tip and dorsum gestures. We conclude by addressing the contributions of EPG to our understanding of L2 speech and highlight avenues for future research including the study of both linguistic and speaker variables.

Shadowing in the manual modality

Motor simulation has emerged as a mechanism for both predictive action perception and language comprehension. By deriving a motor command, individuals can predictively represent the outcome of an unfolding action as a forward model. Evidence of simulation can be seen via improved participant performance for stimuli that conform to the participant's individual characteristics (an egocentric bias). There is little evidence, however, from individuals for whom action and language take place in the same modality: sign language users. The present study asked signers and nonsigners to shadow (perform actions in tandem with various models), and the delay between the model and participant ("lag time") served as an indicator of the strength of the predictive model (shorter lag time = more robust model). This design allowed us to examine the role of (a) motor simulation during action prediction, (b) linguistic status in predictive representations (i.e., pseudosigns vs. grooming gestures), and (c) language experience in generating predictions (i.e., signers vs. nonsigners). An egocentric bias was only observed under limited circumstances: when nonsigners began shadowing grooming gestures. The data do not support strong motor simulation proposals, and instead highlight the role of (a) production fluency and (b) manual rhythm for signer productions. Signers showed significantly faster lag times for the highly skilled pseudosign model and increased temporal regularity (i.e., lower standard deviations) compared to nonsigners. We conclude sign language experience may (a) reduce reliance on motor simulation during action observation, (b) attune users to prosodic cues (c) and induce temporal regularities during action production.

Phonetic convergence to Southern American English: Acoustics and perception

Phonetic convergence is linguistically and socially selective. The current study examined the constraints on this selectivity in convergence to Southern American English by non-Southern Americans in a word shadowing task. Participants were asked either to repeat the words after the model talker, to repeat the words after the model talker from Louisville, KY, or to imitate the way the model talker from Louisville, KY, said the words, in a between-subject design. Acoustic analysis of the participants' productions revealed significant phonetic convergence on word duration and back vowel fronting, but not on /aɪ/ monophthongization, across all three instruction conditions. These findings suggest social selectivity such that convergence on stereotyped variants is avoided, but convergence to a talker with a non-prestigious variety is not. A perceptual assessment of convergence confirmed the acoustic results, but also revealed significantly more convergence in the explicit imitation condition than in the two repetition conditions. These findings suggest that explicit instructions to imitate lead to greater convergence overall, but do not completely override social selectivity. A comparison of the acoustic and perceptual assessments of convergence indicates that they provide complementary insights into specific features and holistic patterns of convergence, respectively.

Phonetic imitation of coarticulatory vowel nasalization

This study investigates the spontaneous phonetic imitation of coarticulatory vowel nasalization. Speakers produced monosyllabic words with a vowel-nasal sequence either from dense or sparse phonological neighborhoods in shadowing and word-naming tasks. During shadowing, they were exposed to target words that were modified to have either an artificially increased or decreased degree of coarticulatory vowel nasality. Increased nasality, which is communicatively more facilitative in that it provides robust predictive information about the upcoming nasal segment, was imitated more strongly during shadowing than decreased nasality. An effect of neighborhood density was also observed only in the increased nasality condition, where high neighborhood density words were imitated more robustly in early shadowing repetition. An effect of exposure to decreased nasality was observed during post-shadowing word-naming only. The observed imitation of coarticulatory nasality provides evidence that speakers and listeners are sensitive to the details of coarticulatory realization, and that imitation need not be mediated by abstract phonological representations. Neither a communicative account nor a representational account could single-handedly predict these observed patterns of imitation. As such, it is argued that these findings support both communicative and representational accounts of phonetic imitation.

Direct Perceptions of Carol Fowler's Theoretical Perspective

Carol Fowler has had a tremendous impact on the field of speech perception, in part by having people disagree with her. The disagreements arise, as they often do, from two incompatible sources: Her positions are often misunderstood and thus "disagreed" with only on the surface, and her positions are rejected because they challenge deeply held, intuitively appealing positions, without being shown to be wrong. The misunderstandings center largely on the assertion that perception is "direct." This is often taken to mean that we have access to the speaker's vocal tract by some means other than the (largely acoustic) speech signal, when, in fact, it asserts that the signal is sufficient to directly specify that production. It is unclear why this misunderstanding persists; while there are still issues to be resolved in this regard, the stance is clear. The challenge to "acoustic" theories of speech perception remains, and thus direct perception is still controversial, as it seems that acoustic theories are held by a majority of researchers. Decades' worth of evidence showing the lack of usefulness of purely acoustic properties and the coherence gained by a production perspective have not changed this situation. Some attempts at combining the two perspectives have emerged, but they largely miss the Gibsonian challenge that Fowler has espoused: Perception of speech is direct. It looks as though it will take some further decades of research and discussion to fully explore her position.

Dimension-Based Statistical Learning Affects Both Speech Perception and Production

Multiple acoustic dimensions signal speech categories. However, dimensions vary in their informativeness; some are more diagnostic of category membership than others. Speech categorization reflects these dimensional regularities such that diagnostic dimensions carry more "perceptual weight" and more effectively signal category membership to native listeners. Yet perceptual weights are malleable. When short-term experience deviates from long-term language norms, such as in a foreign accent, the perceptual weight of acoustic dimensions in signaling speech category membership rapidly adjusts. The present study investigated whether rapid adjustments in listeners' perceptual weights in response to speech that deviates from the norms also affects listeners' own speech productions. In a word recognition task, the correlation between two acoustic dimensions signaling consonant categories, fundamental frequency (F0) and voice onset time (VOT), matched the correlation typical of English, and then shifted to an "artificial accent" that reversed the relationship, and then shifted back. Brief, incidental exposure to the artificial accent caused participants to down-weight perceptual reliance on F0, consistent with previous research. Throughout the task, participants were intermittently prompted with pictures to produce these same words. In the block in which listeners heard the artificial accent with a reversed F0 × VOT correlation, F0 was a less robust cue to voicing in listeners' own speech productions. The statistical regularities of short-term speech input affect both speech perception and production, as evidenced via shifts in how acoustic dimensions are weighted.

Visibility of speech articulation enhances auditory phonetic convergence

Talkers automatically imitate aspects of perceived speech, a phenomenon known as phonetic convergence. Talkers have previously been found to converge to auditory and visual speech information. Furthermore, talkers converge more to the speech of a conversational partner who is seen and heard, relative to one who is just heard (Dias & Rosenblum Perception, 40, 1457-1466, 2011). A question raised by this finding is what visual information facilitates the enhancement effect. In the following experiments, we investigated the possible contributions of visible speech articulation to visual enhancement of phonetic convergence within the noninteractive context of a shadowing task. In Experiment 1, we examined the influence of the visibility of a talker on phonetic convergence when shadowing auditory speech either in the clear or in low-level auditory noise. The results suggest that visual speech can compensate for convergence that is reduced by auditory noise masking. Experiment 2 further established the visibility of articulatory mouth movements as being important to the visual enhancement of phonetic convergence. Furthermore, the word frequency and phonological neighborhood density characteristics of the words shadowed were found to significantly predict phonetic convergence in both experiments. Consistent with previous findings (e.g., Goldinger Psychological Review, 105, 251-279, 1998), phonetic convergence was greater when shadowing low-frequency words. Convergence was also found to be greater for low-density words, contrasting with previous predictions of the effect of phonological neighborhood density on auditory phonetic convergence (e.g., Pardo, Jordan, Mallari, Scanlon, & Lewandowski Journal of Memory and Language, 69, 183-195, 2013). Implications of the results for a gestural account of phonetic convergence are discussed.

Phonetic imitation by young children and its developmental changes

PURPOSE

In the current study, the author investigated the developmental course of phonetic imitation in childhood, and further evaluated existing accounts of phonetic imitation.

METHOD

Sixteen preschoolers, 15 third graders, and 18 college students participated in the current study. An experiment with a modified imitation paradigm with a picture-naming task was conducted, in which participants' voice-onset time (VOT) was compared before and after they were exposed to target speech with artificially increased VOT.

RESULTS

Extended VOT in the target speech was imitated by preschoolers and 3rd graders as well as adults, confirming previous findings in phonetic imitation. Furthermore, an age effect of phonetic imitation was observed; namely, children showed greater imitation than adults, whereas the degree of imitation was comparable between preschoolers and 3rd graders. No significant effect of gender or word specificity was observed.

CONCLUSIONS

Young children imitated fine phonetic details of the target speech, and greater degree of phonetic imitation was observed in children compared to adults. These findings suggest that the degree of phonetic imitation negatively correlates with phonological development.

Is speech alignment to talkers or tasks?

Speech alignment, or the tendency of individuals to subtly imitate each other's speaking styles, is often assessed by comparing a subject's baseline and shadowed utterances to a model's utterances, often through perceptual ratings. These types of comparisons provide information about the occurrence of a change in subject's speech, but they do not indicate that this change is toward the specific shadowed model. In three experiments, we investigated whether alignment is specific to a shadowed model. Experiment 1 involved the classic baseline-to-shadowed comparison, to confirm that subjects did, in fact, sound more like their model when they shadowed, relative to any preexisting similarities between a subject and a model. Experiment 2 tested whether subjects' utterances sounded more similar to the model whom they had shadowed or to another, unshadowed model. In Experiment 3, we examined whether subjects' utterances sounded more similar to the model whom they had shadowed or to another subject who had shadowed a different model. The results of all experiments revealed that subjects sounded more similar to the model whom they had shadowed. This suggests that shadowing-based speech alignment is not just a change, but a change in the direction of the shadowed model, specifically.

Measuring phonetic convergence in speech production

Phonetic convergence is defined as an increase in the similarity of acoustic-phonetic form between talkers. Previous research has demonstrated phonetic convergence both when a talker listens passively to speech and while talkers engage in social interaction. Much of this research has focused on a diverse array of acoustic-phonetic attributes, with fewer studies incorporating perceptual measures of phonetic convergence. The current paper reviews research on phonetic convergence in both non-interactive and conversational settings, and attempts to consolidate the diverse array of findings by proposing a paradigm that models perceptual and acoustic measures together. By modeling acoustic measures as predictors of perceived phonetic convergence, this paradigm has the potential to reconcile some of the diverse and inconsistent findings currently reported in the literature.

Prediction and imitation in speech

It has been suggested that intra- and inter-speaker variability in speech are correlated. Interlocutors have been shown to converge on various phonetic dimensions. In addition, speakers imitate the phonetic properties of voices they are exposed to in shadowing, repetition, and even passive listening tasks. We review three theoretical accounts of speech imitation and convergence phenomena: (i) the Episodic Theory (ET) of speech perception and production (Goldinger, 1998); (ii) the Motor Theory (MT) of speech perception (Liberman and Whalen, 2000; Galantucci et al., 2006); (iii) Communication Accommodation Theory (CAT; Giles and Coupland, 1991; Giles et al., 1991). We argue that no account is able to explain all the available evidence. In particular, there is a need to integrate low-level, mechanistic accounts (like ET and MT), and higher-level accounts (like CAT). We propose that this is possible within the framework of an integrated theory of production and comprehension (Pickering and Garrod, 2013). Similarly to both ET and MT, this theory assumes parity between production and perception. Uniquely, however, it posits that listeners simulate speakers' utterances by computing forward-model predictions at many different levels, which are then compared to the incoming phonetic input. In our account phonetic imitation can be achieved via the same mechanism that is responsible for sensorimotor adaptation; i.e., the correction of prediction errors. In addition, the model assumes that the degree to which sensory prediction errors lead to motor adjustments is context-dependent. The notion of context subsumes both the preceding linguistic input and non-linguistic attributes of the situation (e.g., the speaker's and listener's social identities, their conversational roles, the listener's intention to imitate).

Immediate and Distracted Imitation in Second-Language Speech: Unreleased Plosives In English

The paper investigates immediate and distracted imitation in second-language speech using unreleased plosives. Unreleased plosives are fairly frequently found in English sequences of two stops. Polish, on the other hand, is characterised by a significant rate of releases in such sequences. This cross-linguistic difference served as material to look into how and to what extent non-native properties of sounds can be produced in immediate and distracted imitation. Thirteen native speakers of Polish first read and then imitated sequences of words with two stops straddling the word boundary. Stimuli for imitation had no release of the first stop. The results revealed that (1) a non-native feature such as the lack of the release burst can be imitated; (2) distracting imitation impedes imitative performance; (3) the type of a sequence interacts with the magnitude of an imitative effect