Publications

Abstract

Reduced forms like yeshay for yesterday often occur in conversations. Previous behavioral research reported a processing advantage for full over reduced forms. The present study investigated whether this processing advantage is reflected in a modulation of alpha (8–12 Hz) and gamma (30+ Hz) band activity. In three electrophysiological experiments, participants listened to full and reduced forms in isolation (Experiment 1), sentence-final position (Experiment 2), or mid-sentence position (Experiment 3). Alpha power was larger in response to reduced forms than to full forms, but only in Experiments 1 and 2. We interpret these increases in alpha power as reflections of higher auditory cognitive load. In all experiments, gamma power only increased in response to full forms, which we interpret as showing that lexical activation spreads more quickly through the semantic network for full than for reduced forms. These results confirm a processing advantage for full forms, especially in non-medial sentence position.

Abstract

Amsterdam klinkt in informele gesprekken vaak als Amsdam en Rotterdam als Rodam, zonder dat de meeste moedertaalsprekers zich daar bewust van zijn. In alledaagse situaties valt een aanzienlijk deel van de klanken weg. Daarnaast worden veel klanken zwakker gearticuleerd (bijvoorbeeld een d als een j, als de mond niet helemaal afgesloten wordt). Het lijkt waarschijnlijk dat deze half uitgesproken woorden een probleem vormen voor tweedetaalleerders. Gereduceerde vormen kunnen immers sterk afwijken van de vormen die deze leerders geleerd hebben. Of dit werkelijk zo is, hebben de auteurs onderzocht in twee studies. Voordat ze deze twee studies bespreken, vertellen ze eerst kort iets over de verschillende typen reducties die voorkomen.

Abstract

This paper combines two different approaches to modeling reaction time data from lexical decision experiments, viz. a dataoriented statistical analysis by means of a linear mixed effects model, and a process-oriented computational model of human speech comprehension. The linear mixed effect model is implemented by lmer in R. As computational model we apply DIANA, an end-to-end computational model which aims at modeling the cognitive processes underlying speech comprehension. DIANA takes as input the speech signal, and provides as output the orthographic transcription of the stimulus, a word/non-word judgment and the associated reaction time. Previous studies have shown that DIANA shows good results for large-scale lexical decision experiments in Dutch and North-American English. We investigate whether predictors that appear significant in an lmer analysis and processes implemented in DIANA can be related and inform both approaches. Predictors such as ‘previous reaction time’ can be related to a process description; other predictors, such as ‘lexical neighborhood’ are hard-coded in lmer and emergent in DIANA. The analysis focuses on the interaction between subject variables and task variables in lmer, and the ways in which these interactions can be implemented in DIANA.

Abstract

In spontaneous conversations, words are often produced in reduced form compared to formal careful speech. In English, for instance, ’probably’ may be pronounced as ’poly’ and ’police’ as ’plice’. Reduced forms are very common, and native listeners usually do not have any problems with interpreting these reduced forms in context. Non-native listeners, however, have great difficulties in comprehending reduced forms. In order to investigate the problems in comprehension that non-native listeners experience, a dictation experiment was conducted in which sentences were presented auditorily to non-natives either in full (unreduced) or reduced form. The types of errors made by the L2 listeners reveal aspects of the cognitive processes underlying this dictation task. In addition, we compare the errors made by these human participants with the type of word errors made by DIANA, a recently developed computational model of word comprehension.

Abstract

The majority of studies addressing psycholinguistic questions focus on speech produced and processed in a careful, laboratory speech style. This ‘careful’ speech is very different from the speech that listeners encounter in casual conversations. This article argues that research on casual speech is necessary to show the validity of conclusions based on careful speech. Moreover, research on casual speech produces new insights and questions on the processes underlying communication and on the mental lexicon that cannot be revealed by research using careful speech. This article first places research on casual speech in its historic perspective. It then provides many examples of how casual speech differs from careful speech and shows that these differences may have important implications for psycholinguistic theories. Subsequently, the article discusses the challenges that research on casual speech faces, which stem from the high variability of this speech style, its necessary casual context, and that casual speech is connected speech. We also present opportunities for research on casual speech, mostly in the form of new experimental methods that facilitate research on connected speech. However, real progress can only be made if these new methods are combined with advanced (still to be developed) statistical techniques.

Abstract

Rede uitgesproken bij de aanvaarding van het ambt van hoogleraar Psycholinguïstiek aan de Faculteit der Letteren van de Radboud Universiteit Nijmegen op vrijdag 18 januari 2013

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 investigates the nature of reduction phenomena in informal speech. It addresses the question whether reduction processes that affect many word types, but only if they occur in connected informal speech, may be categorical in nature. The focus is on reduction of schwa in the prefixes and on word-final /t/ in Dutch past participles. More than 2000 tokens of past participles from the Ernestus Corpus of Spontaneous Dutch and the Spoken Dutch Corpus (both from the interview and read speech component) were transcribed automatically. The results demonstrate that the presence and duration of /t/ are affected by approximately the same phonetic variables, indicating that the absence of /t/ is the extreme result of shortening, and thus results from a gradient reduction process. Also for schwa, the data show that mainly phonetic variables influence its reduction, but its presence is affected by different and more variables than its duration, which suggests that the absence of schwa may result from gradient as well as categorical processes. These conclusions are supported by the distributions of the segments’ durations. These findings provide evidence that reduction phenomena which affect many words in informal conversations may also result from categorical reduction processes.

Abstract

An audio and video corpus of speech addressed to 28 11-month-olds is described. The corpus allows comparisons between adult speech directed towards infants, familiar adults and unfamiliar adult addressees, as well as of caregivers’ word teaching strategies across word classes. Summary data show that infant-directed speech differed more from speech to unfamiliar than familiar adults; that word teaching strategies for nominals versus verbs and adjectives differed; that mothers mostly addressed infants with multi-word utterances; and that infants’ vocabulary size was unrelated to speech rate, but correlated positively with predominance of continuous caregiver speech (not of isolated words) in the input.

Abstract

Hoewel de spelling van Nederlandse verledentijdsvormen van zwakke werkwoorden algemeen als eenvoudig wordt beschouwd (ze zijn immers klankzuiver) maken zelfs universiteitsstudenten opvallend veel fouten bij de keuze tussen de uitgangen -te en -de. Voor een deel zijn die fouten ‘natuurlijk’ in die zin dat ze het gevolg zijn van de werking van frequentie en analogie. Anderzijds stellen we vast dat Nederlanders veel meer fouten maken dan Vlamingen, althans als de stam op een coronale fricatief eindigt (s, z, f, v). Aangezien de Nederlandse proefpersonen de ‘regel’ (het ezelsbruggetje ’t kofschip) beter lijken te beheersen dan de Vlamingen, moet de verklaring voor het verschil gezocht worden in een klankverandering die zich wel in Nederland maar niet of nauwelijks in Vlaanderen voordoet, de verstemlozing van de fricatieven. Het spellingprobleem vraagt om didactische maatregelen en/of politieke: het kan wellicht grotendeels worden opgelost door de spellingregels een weinig aan te passen.

Abstract

This paper describes a computational model of speech comprehension that takes the acoustic signal as input and predicts reaction times as observed in an auditory lexical decision task. By doing so, we explore a new generation of end-to-end computational models that are able to simulate the behaviour of human subjects participating in a psycholinguistic experiment. So far, nearly all computational models of speech comprehension do not start from the speech signal itself, but from abstract representations of the speech signal, while the few existing models that do start from the acoustic signal cannot directly model reaction times as obtained in comprehension experiments. The main functional components in our model are the perception stage, which is compatible with the psycholinguistic model Shortlist B and is implemented with techniques from automatic speech recognition, and the decision stage, which is based on the linear ballistic accumulation decision model. We successfully tested our model against data from 20 participants performing a largescale auditory lexical decision experiment. Analyses show that the model is a good predictor for the average judgment and reaction time for each word.

Abstract

This study investigates whether listeners' familiarity with an intonation contour affects speech processing. In three experiments, Dutch participants heard Dutch sentences with normal intonation contours and with unfamiliar ones and performed word-monitoring, lexical decision, or semantic categorisation tasks (the latter two with cross-modal identity priming). The unfamiliar intonation contour slowed down participants on all tasks, which demonstrates that an unfamiliar intonation contour has a robust detrimental effect on speech processing. Since cross-modal identity priming with a lexical decision task taps into lexical access, this effect obtained in this task suggests that an unfamiliar intonation contour hinders lexical access. Furthermore, results from the semantic categorisation task show that the effect of an uncommon intonation contour is long-lasting and hinders subsequent processing. Hence, intonation not only contributes to utterance meaning (emotion, sentence type, and focus), but also affects crucial aspects of the speech comprehension process and is more important than previously thought.

Abstract

Paper presented at The 161th Meeting Acoustical Society of America, Seattle, Washington, 23-27 May 2011. Reduction in casual speech can create ambiguity, e.g., “he was” can sound like “he’s.” Before quotative “like” “so she’s/she was like…”, it was found that there is little accurate acoustic information about the distinction in the signal. This work examines what types of information acoustics of the target itself, speech rate, coarticulation, and syntax/semantics listeners use to recognize such reduced function words. We compare perception studies presenting the targets auditorily with varying amounts of context, presenting the context without the targets, and a visual study presenting context in written form. Given primarily discourse information visual or auditory context only, subjects are strongly biased toward past, reflecting the use of quotative “like” for reporting past speech. However, if the target itself is presented, the direction of bias reverses, indicating that listeners favor acoustic information within the target which is reduced, sounding like the shorter, present form over almost any other source of information. Furthermore, when the target is presented auditorily with surrounding context, the bias shifts slightly toward the direction shown in the orthographic or auditory-no-target experiments. Thus, listeners prioritize acoustic information within the target when present, even if that information is misleading, but they also take discourse information into account.

Abstract

This study presents an analysis of over 4000 tokens of words produced as variants with and without schwa in a French corpus of radio-broadcasted speech. In order to determine which of the many variables mentioned in the literature influence variant choice, 17 predictors were tested in the same analysis. Only five of these variables appeared to condition variant choice. The question of the processing stage, or locus, of this alternation process is also addressed in a comparison of the variables that predict variant choice with the variables that predict the acoustic duration of schwa in variants with schwa. Only two variables predicting variant choice also predict schwa duration. The limited overlap between the predictors for variant choice and for schwa duration, combined with the nature of these variables, suggest that the variants without schwa do not result from a phonetic process of reduction; that is, they are not the endpoint of gradient schwa shortening. Rather, these variants are generated early in the production process, either during phonological encoding or word-form retrieval. These results, based on naturally produced speech, provide a useful complement to on-line production experiments using artificial speech tasks.

Abstract

Words are often pronounced very differently in formal speech than in everyday conversations. In conversational speech, they may contain weaker segments, fewer sounds, and even fewer syllables. The English word yesterday, for instance, may be pronounced as [j epsilon integral eI]. This article forms an introduction to the phenomenon of reduced pronunciation variants and to the eight research articles in this issue on the characteristics, production, and comprehension of these variants. We provide a description of the phenomenon, addressing its high frequency of occurrence in casual conversations in various languages, the gradient nature of many reduction processes, and the intelligibility of reduced variants to native listeners. We also describe the relevance of research on reduced variants for linguistic and psychological theories as well as for applications in speech technology and foreign language acquisition. Since reduced variants occur more often in spontaneous than in formal speech, they are hard to study in the laboratory under well controlled conditions. We discuss the advantages and disadvantages of possible solutions, including the research methods employed in the articles in this special issue, based on corpora and experiments. This article ends with a short overview of the articles in this issue.

Abstract

This corpus study demonstrates that the realization of wordfinal /t/ in Dutch past-participles in various speech styles is affected by a word’s predictability and paradigmatic relative frequency. In particular, /t/s are shorter and more often absent if the two preceding words are more predictable. In addition, /t/s, especially in irregular verbs, are more reduced, the lower the verb’s lemma frequency relative to the past-participle’s frequency. Both effects are more pronounced in more spontaneous speech. These findings are expected if speech planning plays an important role in speech reduction. Index Terms: pronunciation variation, acoustic reduction, corpus research, word predictability, morphological decomposability

Abstract

This study investigates the prosodic conditioning of phonetic details which are candidate cues to phonological contrasts. German /b, d, g, p, t, k/ were examined in three prosodic positions. Lenis plosives /b, d, g/ were produced with less glottal vibration at larger prosodic boundaries, whereas their VOT showed no effect of prosody. VOT of fortis plosives /p, t, k/ decreased at larger boundaries, as did their burst intensity maximum. Vowels (when measured from consonantal release) following fortis plosives and lenis velars were shorter after larger boundaries. Closure duration, which did not contribute to the fortis/lenis contrast, was heavily affected by prosody. These results support neither of the hitherto proposed accounts of prosodic strengthening (Uniform Strengthening and Feature Enhancement). We propose a different account, stating that the phonological identity of speech sounds remains stable not only within, but also across prosodic positions (contrast-over-prosody hypothesis). Domain-initial strengthening hardly diminishes the contrast between prosodically weak fortis and strong lenis plosives.

Abstract

In spontaneous, conversational speech, words are often reduced compared to their citation forms, such that a word like yesterday may sound like [’jεsmall eshei]. The present chapter investigates such acoustic reduction. The study of reduction needs large corpora that are transcribed phonetically. The first part of this chapter describes an automatic transcription procedure used to obtain such a large phonetically transcribed corpus of Dutch spontaneous dialogues, which is subsequently used for the investigation of acoustic reduction. First, the orthographic transcriptions were adapted for automatic processing. Next, the phonetic transcription of the corpus was created by means of a forced alignment using a lexicon with multiple pronunciation variants per word. These variants were generated by applying phonological and reduction rules to the canonical phonetic transcriptions of the words. The second part of this chapter reports the results of a quantitative analysis of reduction in the corpus on the basis of the generated transcriptions and gives an inventory of segmental reductions in standard Dutch. Overall, we found that reduction is more pervasive in spontaneous Dutch than previously documented.

Abstract

This paper presents a method to quantify the spectral characteristics of reduction in speech. Hämäläinen et al. (2009) proposes a measure of spectral reduction which is able to predict a substantial amount of the variation in duration that linguistically motivated variables do not account for. In this paper, we continue studying acoustic reduction in speech by developing a new acoustic measure of reduction, based on local manifold structure in speech. We show that this measure yields significantly improved statistical models for predicting variation in duration.

Abstract

The present study compares the realization of intervocalic voiceless stops and vowels surrounded by voiceless stops in conversational Spanish and French. Our data reveal significant differences in how these segments are realized in each language. Spanish voiceless stops tend to have shorter stop closures, display incomplete closures more often, and exhibit more voicing than French voiceless stops. As for vowels, more cases of complete devoicing and greater degrees of partial devoicing were found in French than in Spanish. Moreover, all French vowel types exhibit significantly lower F1 values than their Spanish counterparts. These findings indicate that the extent of reduction that a segment type can undergo in conversational speech can vary significantly across languages. Language differences in coarticulatory strategies and “base-of-articulation” are discussed as possible causes of our observations.

Abstract

This study investigates the reduction of vowel /e/ in the French word c’était /setε/ ‘it was’. This reduction phenomenon appeared to be highly frequent, as more than half of the occurrences of this word in a corpus of casual French contained few or no acoustic traces of a vowel between [s] and [t]. All our durational analyses clearly supported a categorical absence of vowel /e/ in a subset of c’était tokens. This interpretation was also supported by our finding that the occurrence of complete elision and [e] duration in non-elision tokens were conditioned by different factors. However, spectral measures were consistent with the possibility that a highly reduced /e/ vowel is still present in elision tokens in spite of the durational evidence for categorical elision. We discuss how these findings can be reconciled, and conclude that acoustic analysis of uncontrolled materials can provide valuable information about the mechanisms underlying reduction phenomena in casual speech.

Abstract

This study investigates the lifespans of lexical traces for novel morphologically complex words. In two visual lexical decision experiments, a neologism was either primed by itself or by its stem. The target occurred 40 trials after the prime (Experiments 1 & 2), after a 12 hour delay (Experiment 1), or after a one week delay (Experiment 2). Participants recognized neologisms more quickly if they had seen them before in the experiment. These results show that memory traces for novel morphologically complex words already come into existence after a very first exposure and that they last for at least a week. We did not find evidence for a role of sleep in the formation of memory traces. Interestingly, Base Frequency appeared to play a role in the processing of the neologisms also when they were presented a second time and had their own memory traces.

Abstract

Listeners require context to understand the highly reduced words that occur in casual speech. The present study reports four auditory lexical decision experiments in which the role of semantic context in the comprehension of reduced versus unreduced speech was investigated. Experiments 1 and 2 showed semantic priming for combinations of unreduced, but not reduced, primes and low-frequency targets. In Experiment 3, we crossed the reduction of the prime with the reduction of the target. Results showed no semantic priming from reduced primes, regardless of the reduction of the targets. Finally, Experiment 4 showed that reduced and unreduced primes facilitate upcoming low-frequency related words equally if the interstimulus interval is extended. These results suggest that semantically related words need more time to be recognized after reduced primes, but once reduced primes have been fully (semantically) processed, these primes can facilitate the recognition of upcoming words as well as do unreduced primes.