Publications

Abstract

This study investigated pronunciation variants of word-final obstruent-liquid-schwa (OLS) clusters in casual French and the variables predicting the absence of the phonemes in these clusters. In a dataset of 291 noun tokens extracted from a corpus of casual conversations, we observed that in 80.7% of the tokens, at least one phoneme was absent and that in no less than 15.5% the whole cluster was absent (e.g., /mis/ for ministre). Importantly, the probability of a phoneme being absent was higher if the following phoneme was absent as well. These data show that reduction can affect several phonemes at once and is not restricted to just a handful of (function) words. Moreover, our results demonstrate that the absence of each single phoneme is affected by the speaker's tendency to increase ease of articulation and to adapt a word's pronunciation variant to the time available.

Abstract

The present study investigated the effect of orthography on the learning and subsequent processing of pronunciation variants in a second language. Dutch learners of French learned reduced pronunciation variants that result from schwa-zero alternation in French (e.g., reduced /ʃnij/ from chenille 'caterpillar'). Half of the participants additionally learnt the words' spellings, which correspond more closely to the full variants with schwa. On the following day, participants performed an auditory lexical decision task, in which they heard half of the words in their reduced variants, and the other half in their full variants. Participants who had exclusively learnt the auditory forms performed significantly worse on full variants than participants who had also learnt the spellings. This shows that learners integrate phonological and orthographic information to process pronunciation variants. There was no difference between both groups in their performances on reduced variants, suggesting that the exposure to spelling does not impede learners' processing of these variants.

Abstract

In an auditory lexical decision experiment, 5,541 spoken content words and pseudo-words were presented to 20 native speakers of Dutch. The words vary in phonological makeup and in number of syllables and stress pattern, and are further representative of the native Dutch vocabulary in that most are morphologically complex, comprising two stems or one stem plus derivational and inflectional suffixes, with inflections representing both regular and irregular paradigms; the pseudo-words were matched in these respects to the real words. The BALDEY data file includes response times and accuracy rates, with for each item morphological information plus phonological and acoustic information derived from automatic phonemic segmentation of the stimuli. Two initial analyses illustrate how this data set can be used. First, we discuss several measures of the point at which a word has no further neighbors, and compare the degree to which each measure predicts our lexical decision response outcomes. Second, we investigate how well four different measures of frequency of occurrence (from written corpora, spoken corpora, subtitles and frequency ratings by 70 participants) predict the same outcomes. These analyses motivate general conclusions about the auditory lexical decision task. The (publicly available) BALDEY database lends itself to many further analyses.

Abstract

This article presents two studies investigating how the situation in which speech is uttered affects the frequency with which words are reduced. Study 1 is based on the Spoken Dutch Corpus, which consists of 15 components, nearly all representing a different speech situation. This study shows that the components differ in how often ten semantically weak words are highly reduced. The differences are especially large between the components with scripted and unscripted speech. Within the component group of unscripted speech, the formality of the situation shows an effect. Study 2 investigated segment reduction in a shadowing experiment in which participants repeated Dutch carefully and casually articulated sentences. Prefixal schwa and suffixal /t/ were absent in participants' responses to both sentences types as often as in formal interviews. If a segment was absent, this appeared to be mostly due to extreme co-articulation, unlike in speech produced in less formal situations. Speakers thus adapted more to the formal situation of the experiment than to the stimuli to be shadowed. We conclude that speech situation affects the occurrence of reduced word pronunciation variants, which should be accounted for by psycholinguistic models of speech production and comprehension

Abstract

This paper investigates whether individual speakers forming a homogeneous group differ in their choice and pronunciation of words when engaged in casual conversation, and if so, how they differ. More specifically, it examines whether the Balanced Winnow classifier is able to distinguish between the twenty speakers of the Ernestus Corpus of Spontaneous Dutch, who all have the same social background. To examine differences in choice and pronunciation of words, instead of characteristics of the speech signal itself, classification was based on lexical and pronunciation features extracted from hand-made orthographic and automatically generated broad phonetic transcriptions. The lexical features consisted of words and two-word combinations. The pronunciation features represented pronunciation variations at the word and phone level that are typical for casual speech. The best classifier achieved a performance of 79.9% and was based on the lexical features and on the pronunciation features representing single phones and triphones. The speakers must thus differ from each other in these features. Inspection of the relevant features indicated that, among other things, the words relevant for classification generally do not contain much semantic content, and that speakers differ not only from each other in the use of these words but also in their pronunciation.

Abstract

This paper studies the robustness of exemplar effects in word comprehension by means of four long-term priming experiments with lexical decision tasks in Dutch. A prime and target represented the same word type and were presented with the same or different degree of reduction. In Experiment 1, participants heard only a small number of trials, a large proportion of repeated words, and stimuli produced by only one speaker. They recognized targets more quickly if these represented the same degree of reduction as their primes, which forms additional evidence for the exemplar effects reported in the literature. Similar effects were found for two speakers who differ in their pronunciations. In Experiment 2, with a smaller proportion of repeated words and more trials between prime and target, participants recognized targets preceded by primes with the same or a different degree of reduction equally quickly. Also, in Experiments 3 and 4, in which listeners were not exposed to one but two types of pronunciation variation (reduction degree and speaker voice), no exemplar effects arose. We conclude that the role of exemplars in speech comprehension during natural conversations, which typically involve several speakers and few repeated content words, may be smaller than previously assumed.

Abstract

This paper investigated the learnability and generalizability of French schwa alternation by Dutch low-proficiency second language learners. We trained 40 participants on 24 new schwa words by exposing them equally often to the reduced and full forms of these words. We then assessed participants' accuracy and reaction times to these newly learnt words as well as 24 previously encountered schwa words with an auditory lexical decision task. Our results show learning of the new words in both forms. This suggests that lack of exposure is probably the main cause of learners' difficulties with reduced forms. Nevertheless, the full forms were slightly better recognized than the reduced ones, possibly due to phonetic and phonological properties of the reduced forms. We also observed no generalization to previously encountered words, suggesting that our participants stored both of the learnt word forms and did not create a rule that applies to all schwa words.

Abstract

In speech, words are often reduced rather than fully pronounced (e.g., (/ˈsʌmri/ for /ˈsʌməri/, summary). Non-native listeners may have problems in processing these reduced forms, because they have encountered them less often. This paper addresses the question whether this also holds for highly proficient non-natives and for words with similar forms and meanings in the non-natives' mother tongue (i.e., cognates). In an English auditory lexical decision task, natives and highly proficient Dutch non-natives of English listened to cognates and non-cognates that were presented in full or without their post-stress schwa. The data show that highly proficient learners are affected by reduction as much as native speakers. Nevertheless, the two listener groups appear to process reduced forms differently, because non-natives produce more errors on reduced cognates than on non-cognates. While listening to reduced forms, non-natives appear to be hindered by the co-activated lexical representations of cognate forms in their native language.

Abstract

This paper studies the influence of adverse listening conditions on exemplar effects in priming experiments that do not instruct participants to use their episodic memories. We conducted two lexical decision experiments, in which a prime and a target represented the same word type and could be spoken by the same or a different speaker. In Experiment 1, participants listened to clear speech, and showed no exemplar effects: they recognised repetitions by the same speaker as quickly as different speaker repetitions. In Experiment 2, the stimuli contained noise, and exemplar effects did arise. Importantly, Experiment 1 elicited longer average RTs than Experiment 2, a result that contradicts the time-course hypothesis, according to which exemplars only play a role when processing is slow. Instead, our findings support the hypothesis that exemplar effects arise under adverse listening conditions, when participants are stimulated to use their episodic memories in addition to their mental lexicons.

Abstract

This paper presents DIANA, a new computational model of human speech processing. It is the first model that simulates the complete processing chain from the on-line processing of an acoustic signal to the execution of a response, including reaction times. Moreover it assumes minimal modularity. DIANA consists of three components. The activation component computes a probabilistic match between the input acoustic signal and representations in DIANA’s lexicon, resulting in a list of word hypotheses changing over time as the input unfolds. The decision component operates on this list and selects a word as soon as sufficient evidence is available. Finally, the execution component accounts for the time to execute a behavioral action. We show that DIANA well simulates the average participant in a word recognition experiment.

Abstract

DIANA is an end-to-end computational model of speech processing, which takes as input the speech signal, and provides as output the orthographic transcription of the stimulus, a word/non-word judgment and the associated estimated reaction time. So far, the model has only been tested for Dutch. In this paper, we extend DIANA such that it can also process North American English. The model is tested by having it simulate human participants in a large scale North American English lexical decision experiment. The simulations show that DIANA can adequately approximate the reaction times of an average participant (r = 0.45). In addition, they indicate that DIANA does not yet adequately model the cognitive processes that take place after stimulus offset.