Publications

Abstract

n casual conversations, words often lack segments. This study investigates whether listeners rely on their experience with reduced word pronunciation variants during the processing of single segment reduction. We tested three groups of listeners in a lexical decision experiment with French words produced either with or without word-medial schwa (e.g., /ʀəvy/ and /ʀvy/ for revue). Participants also rated the relative frequencies of the two pronunciation variants of the words. If the recognition accuracy and reaction times for a given listener group correlate best with the frequencies of occurrence holding for that given listener group, recognition is influenced by listeners’ exposure to these variants. Native listeners' relative frequency ratings correlated well with their accuracy scores and RTs. Dutch advanced learners' accuracy scores and RTs were best predicted by their own ratings. In contrast, the accuracy and RTs from Dutch beginner learners of French could not be predicted by any relative frequency rating; the rating task was probably too difficult for them. The participant groups showed behaviour reflecting their difference in experience with the pronunciation variants. Our results strongly suggest that listeners store the frequencies of occurrence of pronunciation variants, and consequently the variants themselves

Abstract

This article presents the ventriloquist paradigm, an innovative method for studying speech processing in dialogue whereby participants interact face-to-face with a confederate who, unbeknownst to them, communicates by playing pre-recorded speech. Results show that the paradigm convinces more participants that the speech is live than a setup without the face-to-face element, and it elicits more interactive conversation than a setup in which participants believe their partner is a computer. By reconciling the ecological validity of a conversational context with full experimental control over phonetic exposure, the paradigm offers a wealth of new possibilities for studying speech processing in interaction.

Abstract

Research questions:

Are emergent bilinguals sensitive to register variation in their use of communication strategies? What strategies do LX speakers, in casu Spanish speakers of English, use as a function of situational context? What role do individual differences play?
Methodology:

This within-speaker study compares Spanish second-language English speakers’ communication strategy use in an informal, peer-to-peer conversation and a formal interview.
Data and analysis:

The 15 hours of informal and 9.5 hours of formal speech from the Nijmegen Corpus of Spanish English were coded for 19 different communication strategies.
Findings/conclusions:

Overall, speakers prefer self-reliant strategies, which allow them to continue communication without their interlocutor’s help. Of the self-reliant strategies, least effort strategies such as code-switching are used more often in informal speech, whereas relatively more effortful strategies (e.g. reformulations) are used more in informal speech, when the need to be unambiguously understood is felt as more important. Individual differences played a role: some speakers were more affected by a change in formality than others.
Originality:

Sensitivity to register variation has not yet been studied within communicative strategy use.
Implications:

General principles of communication govern speakers’ strategy selection, notably the protection of positive face and the least effort and cooperative principles.

Abstract

English serves as a lingua franca in situations with varying degrees of
formality. How formality affects non-native speech has rarely been studied. We
investigated register variation by Spanish users of English by comparing formal
and informal speech from the Nijmegen Corpus of Spanish English that we
created. This corpus comprises speech from thirty-four Spanish speakers of
English in interaction with Dutch confederates in two speech situations.
Formality affected the amount of laughter and overlapping speech and the
number of Spanish words. Moreover, formal speech had a more informational
character than informal speech. We discuss how our findings relate to register
variation in Spanish

Abstract

Sequences of reaction times (RT) produced by participants in an experiment are not only influenced by the stimuli, but by many other factors as well, including fatigue, attention, experience, IQ, handedness, etc. These confounding factors result in longterm effects (such as a participant’s overall reaction capability) and in short- and medium-time fluctuations in RTs (often referred to as ‘local speed effects’). Because stimuli are usually presented in a random sequence different for each participant, local speed effects affect the underlying ‘true’ RTs of specific trials in different ways across participants. To be able to focus statistical analysis on the effects of the cognitive process under study, it is necessary to reduce the effect of confounding factors as much as possible. In this paper we propose and compare techniques and criteria for doing so, with focus on reducing (‘filtering’) the local speed effects. We show that filtering matters substantially for the significance analyses of predictors in linear mixed effect regression models. The performance of filtering is assessed by the average between-participant correlation between filtered RT sequences and by Akaike’s Information Criterion, an important measure of the goodness-of-fit of linear mixed effect regression models.

Abstract

In natural conversations, words are generally shorter and they often lack segments. It is unclear to what extent such durational and segmental reductions affect word recognition. The present study investigates to what extent reduction in the initial syllable hinders word comprehension, which types of segments listeners mostly rely on, and whether listeners use word duration as a cue in word recognition. We conducted three experiments in Dutch, in which we adapted the gating paradigm to study the comprehension of spontaneously uttered conversational speech by aligning the gates with the edges of consonant clusters or vowels. Participants heard the context and some segmental and/or durational information from reduced target words with unstressed initial syllables. The initial syllable varied in its degree of reduction, and in half of the stimuli the vowel was not clearly present. Participants gave too short answers if they were only provided with durational information from the target words, which shows that listeners are unaware of the reductions that can occur in spontaneous speech. More importantly, listeners required fewer segments to recognize target words if the vowel in the initial syllable was absent. This result strongly suggests that this vowel hardly plays a role in word comprehension, and that its presence may even delay this process. More important are the consonants and the stressed vowel.

Abstract

This study examines the influence of orthography on the processing of reduced word forms. For this purpose, we compared the impact of phonological variation with the impact of spelling-sound consistency on the processing of words that may be produced with or without the vowel schwa. Participants learnt novel French words in which the vowel schwa was present or absent in the first syllable. In Experiment 1, the words were consistently produced without schwa or produced in a variable manner (i.e., sometimes produced with and sometimes produced without schwa). In Experiment 2, words were always produced in a consistent manner, but an orthographic exposure phase was included in which words that were produced without schwa were either spelled with or without the letter . Results from naming and eye-tracking tasks suggest that both phonological variation and spelling-sound consistency influence the processing of spoken novel words. However, the influence of phonological variation outweighs the effect of spelling-sound consistency. Our findings therefore suggest that the influence of orthography on the processing of reduced word forms is relatively small.

Abstract

This study addresses the extent to which the location of primary stress in Dutch, German, and English monomorphemic words is affected by the syllables preceding the three final syllables. We present analyses of the monomorphemic words in the CELEX lexical database, which showed that penultimate primary stress is less frequent in Dutch and English trisyllabic than quadrisyllabic words. In addition, we discuss paper-and-pencil experiments in which native speakers assigned primary stress to pseudowords. These experiments provided evidence that in all three languages penultimate stress is more likely in quadrisyllabic than in trisyllabic words. We explain this length effect with the preferences in these languages for word-initial stress and for alternating patterns of stressed and unstressed syllables. The experimental data also showed important intra- and interspeaker variation, and they thus form a challenging test case for theories of language variation.

Abstract

This paper explores the relationship between the acoustic duration of phonemic sequences and their frequencies of occurrence. The data were obtained from large (sub)corpora of spontaneous speech in Dutch, English, German, and Italian. Acoustic duration of an n-phone is shown to codetermine the n-phone's frequency of use, such that languages preferentially use diphones and triphones that are neither very long nor very short. The observed distributions are well approximated by a theoretical function that quantifies the concurrent action of the self-regulatory processes of minimization of articulatory effort and minimization of perception effort

Abstract

This study reports a shadowing experiment, in which one has to repeat a speech stimulus as fast as possible. We tested claims about a direct link between perception and production based on speech gestures, and obtained two types of counterevidence. First, shadowing is not slowed down by a gestural mismatch between stimulus and response. Second, phonetic detail is more likely to be imitated in a shadowing task if it is phonologically relevant. This is consistent with the idea that speech perception and speech production are only loosely coupled, on an abstract phonological level.

Abstract

In four experiments, we investigated how listeners compensate for reduced /t/ in Dutch. Mitterer and Ernestus [Mitterer,H., & Ernestus, M. (2006). Listeners recover /t/s that speakers lenite: evidence from /t/-lenition in Dutch. Journal of Phonetics, 34, 73–103] showed that listeners are biased to perceive a /t/ more easily after /s/ than after /n/, compensating for the tendency of speakers to reduce word-final /t/ after /s/ in spontaneous conversations. We tested the robustness of this phonological context effect in perception with three very different experimental tasks: an identification task, a discrimination task with native listeners and with non-native listeners who do not have any experience with /t/-reduction,and a passive listening task (using electrophysiological dependent measures). The context effect was generally robust against these experimental manipulations, although we also observed some deviations from the overall pattern. Our combined results show that the context effect in compensation for reduced /t/ results from a complex process involving auditory constraints, phonological learning, and lexical constraints.

Abstract

This study investigates the roles of phonetic analogy and lexical frequency in an ongoing sound change, the devoicing of fricatives in Dutch, which occurs mainly in the Netherlands and to a lesser degree in Flanders. In the experiment, Dutch and Flemish students read two variants of 98 words: the standard and a nonstandard form with the incorrect voice value of the fricative. Dutch students chose the non-standard forms with devoiced fricatives more often than Flemish students. Moreover, devoicing, though a gradual process, appeared lexically diffused, affecting first the words that are low in frequency and phonetically similar to words with voiceless fricatives.

Abstract

This paper presents the steps needed to make a corpus of Dutch spontaneous dialogues accessible for automatic phonetic research aimed at increasing our understanding of reduction phenomena and the role of fine phonetic detail. Since the corpus was not created with automatic processing in mind, it needed to be reshaped. The first part of this paper describes the actions needed for this reshaping in some detail. The second part reports the results of a preliminary analysis of the reduction phenomena in the corpus. For this purpose a phonemic transcription of the corpus was created by means of a forced alignment, first with a lexicon of canonical pronunciations and then with multiple pronunciation variants per word. In this study pronunciation variants were generated by applying a large set of phonetic processes that have been implicated in reduction to the canonical pronunciations of the words. This relatively straightforward procedure allows us to produce plausible pronunciation variants and to verify and extend the results of previous reduction studies reported in the literature.

Abstract

This study reports general and language-specific patterns in phoneme identification. In a series of phoneme monitoring experiments, Castilian Spanish, Catalan, Dutch, English, and Polish listeners identified vowel, fricative, and stop consonant targets that are phonemic in all these languages, embedded in nonsense words. Fricatives were generally identified more slowly than vowels, while the speed of identification for stop consonants was highly dependent on the onset of the measurements. Moreover, listeners' response latencies and accuracy in detecting a phoneme correlated with the number of categories within that phoneme's class in the listener's native phoneme repertoire: more native categories slowed listeners down and decreased their accuracy. We excluded the possibility that this effect stems from differences in the frequencies of occurrence of the phonemes in the different languages. Rather, the effect of the number of categories can be explained by general properties of the perception system, which cause language-specific patterns in speech processing.

Abstract

In mainstream phonology, contrastive properties, like stem-final voicing, are simply listed in the lexicon. This article reviews experimental evidence that such contrastive properties may be predictable to some degree and that the relevant statistically gradient generalizations form an inherent part of the grammar. The evidence comes from the underlying voice specification of stem-final obstruents in Dutch. Contrary to received wisdom, this voice specification is partly predictable from the obstruent’s manner and place of articulation and from the phonological properties of the preceding segments. The degree of predictability, which depends on the exact contents of the lexicon, directs speakers’ guesses of underlying voice specifications. Moreover, existing words that disobey the generalizations are disadvantaged by being recognized and produced more slowly and less accurately, also under natural conditions.We discuss how these observations can be accounted for in two types of different approaches to grammar, Stochastic Optimality Theory and exemplar-based modeling.

Abstract

Acoustic duration and degree of vowel reduction are known to correlate with a word’s frequency of occurrence. The present study broadens the research on the role of frequency in speech production to voice assimilation. The test case was regressive voice assimilation in Dutch. Clusters from a corpus of read speech were more often perceived as unassimilated in lower-frequency words and as either completely voiced regressive assimilation or, unexpectedly, as completely voiceless progressive assimilation in higher-frequency words. Frequency did not predict the voice classifications over and above important acoustic cues to voicing, suggesting that the frequency effects on the classifications were carried exclusively by the acoustic signal. The duration of the cluster and the period of glottal vibration during the cluster decreased while the duration of the release noises increased with frequency. This indicates that speakers reduce articulatory effort for higher-frequency words, with some acoustic cues signaling more voicing and others less voicing. A higher frequency leads not only to acoustic reduction but also to more assimilation.

Abstract

In German, word-initial lax fricatives may be produced with substantially reduced glottal vibration after voiceless obstruents. This assimilation occurs more frequently and to a larger extent across prosodic word boundaries than across phrase boundaries. Assimilatory devoicing makes the fricatives more similar to their tense counterparts and could thus hinder word recognition. The present study investigates how listeners cope with assimilatory devoicing. Results of a cross-modal priming experiment indicate that listeners compensate for assimilation in appropriate contexts. Prosodic structure moderates compensation for assimilation: Compensation occurs especially after phrase boundaries, where devoiced fricatives are sufficiently long to be confused with their tense counterparts.

Abstract

Prosodic structure has long been known to constrain phonological processes [1]. More recently, it has also been recognized as a source of fine-grained phonetic variation of speech sounds. In particular, segments in domain-initial position undergo prosodic strengthening [2, 3], which also implies more resistance to coarticulation in higher prosodic domains [5]. The present study investigates the combined effects of prosodic strengthening and assimilatory devoicing on word-initial fricatives in German, the functional implication of both processes for cues to the fortis-lenis contrast, and the influence of prosodic structure on listeners’ compensation for assimilation. Results indicate that 1. Prosodic structure modulates duration and the degree of assimilatory devoicing, 2. Phonological contrasts are maintained by speakers, but differ in phonetic detail across prosodic domains, and 3. Compensation for assimilation in perception is moderated by prosodic structure and lexical constraints.

Abstract

In everyday speech, words may be reduced. Little is known about the consequences of such reductions for spoken word comprehension. This study investigated /t/-lenition in Dutch in two corpus studies and three perceptual experiments. The production studies revealed that /t/-lenition is most likely to occur after [s] and before bilabial consonants. The perception experiments showed that listeners take into account both phonological context, phonetic detail, and the lexical status of the form in the interpretation of codas that may or may not contain a lenited word-final /t/. These results speak against models of word recognition that make hard decisions on a prelexical level.

Abstract

This study investigates whether the acoustic durations of derivational affixes in Dutch are affected by the frequency of the word they occur in. In a word naming experiment, subjects were presented with a large number of words containing one of the affixes ge-, ver-, ont, or -lijk. Their responses were recorded on DAT tapes, and the durations of the affixes were measured using Automatic Speech Recognition technology. To investigate whether frequency also affected durations when speech rate was high, the presentation rate of the stimuli was varied. The results show that a higher frequency of the word as a whole led to shorter acoustic realizations for all affixes. Furthermore, affixes became shorter as the presentation rate of the stimuli increased. There was no interaction between word frequency and presentation rate, suggesting that the frequency effect also applies in situations in which the speed of articulation is very high.

Abstract

This paper describes ongoing research aiming at the description of variation in speech as represented by asynchronous articulatory features. We will first illustrate how distances in the articulatory feature space can be used for event detection along speech trajectories in this space. The temporal structure imposed by the cosine distance in articulatory feature space coincides to a large extent with the manual segmentation on phone level. The analysis also indicates that the articulatory feature representation provides better such alignments than the MFCC representation does. Secondly, we will present first results that indicate that articulatory features can be used to probe for acoustic differences in the onsets of Dutch singulars and plurals.

Abstract

The distribution of energy across the noise spectrum provides the primary cues for the identification of a fricative. Formant transitions have been reported to play a role in identification of some fricatives, but the combined results so far are conflicting. We report five experiments testing the hypothesis that listeners differ in their use of formant transitions as a function of the presence of spectrally similar fricatives in their native language. Dutch, English, German, Polish, and Spanish native listeners performed phoneme monitoring experiments with pseudowords containing either coherent or misleading formant transitions for the fricatives / s / and / f /. Listeners of German and Dutch, both languages without spectrally similar fricatives, were not affected by the misleading formant transitions. Listeners of the remaining languages were misled by incorrect formant transitions. In an untimed labeling experiment both Dutch and Spanish listeners provided goodness ratings that revealed sensitivity to the acoustic manipulation. We conclude that all listeners may be sensitive to mismatching information at a low auditory level, but that they do not necessarily take full advantage of all available systematic acoustic variation when identifying phonemes. Formant transitions may be most useful for listeners of languages with spectrally similar fricatives.

Abstract

This auditory lexical decision study shows that cohort entropies, conditional root uniqueness points, and morphological family size all contribute to the dynamics of the auditory comprehension of prefixed words. Three entropy measures calculated for different positions in the stem of Dutch prefixed words revealed facilitation for higher entropies, except at the point of disambiguation, where we observed inhibition. Morphological family size was also facilitatory, but only for prefixed words in which the conditional root uniqueness point coincided with the conventional uniqueness point. For words with early conditional disambiguation, in contrast, only the morphologically related words that were onset-aligned with the target word facilitated lexical decision.