Publications

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.

Abstract

This paper discusses four experiments on Dutch which show that distinctive phonological features differ in their relevance for word recognition. The relevance of a feature for word recognition depends on its phonological stability, that is, the extent to which that feature is generally realized in accordance with its lexical specification in the relevant word position. If one feature value is uninformative, all values of that feature are less relevant for word recognition, with the least informative feature being the least relevant. Features differ in their relevance both in spoken and written word recognition, though the differences are more pronounced in auditory lexical decision than in self-paced reading.

Abstract

This study addresses the question to what extent the production of regular past tense forms in Dutch is a¤ected by analogical processes. We report an experiment in which native speakers of Dutch listened to existing regular verbs over headphones, and had to indicate which of the past tense allomorphs, te or de, was appropriate for these verbs. According to generative analyses, the choice between the two su‰xes is completely regular and governed by the underlying [voice]-specification of the stem-final segment. In this approach, no analogical e¤ects are expected. In connectionist and analogical approaches, by contrast, the phonological similarity structure in the lexicon is expected to a¤ect lexical processing. Our experimental results support the latter approach: all participants created more nonstandard past tense forms, produced more inconsistency errors, and responded more slowly for verbs with stronger analogical support for the nonstandard form.

Abstract

Listeners cannot recognize highly reduced word forms in isolation, but they can do so when these forms are presented in context (Ernestus, Baayen, & Schreuder, 2002). This suggests that not all possible surface forms of words have equal status in the mental lexicon. The present study shows that the reduced forms are linked to the canonical representations in the mental lexicon, and that these latter representations induce reconstruction processes. Listeners restore suffixes that are partly or completely missing in reduced word forms. A series of phoneme-monitoring experiments reveals the nature of this restoration: the basis for suffix restoration is mainly phonological in nature, but orthography has an influence as well.

Abstract

In this paper, we show that both token and type-based effects in lexical processing can result from a single, token-based, system, and therefore, do not necessarily reflect different levels of processing. We report three Simple Recurrent Networks modeling Dutch past-tense formation. These networks show token-based frequency effects and type-based analogical effects closely matching the behavior of human participants when producing past-tense forms for both existing verbs and pseudo-verbs. The third network covers the full vocabulary of Dutch, without imposing predefined linguistic structure on the input or output words.

Abstract

This paper discusses some pitfalls in corpus research and suggests solutions on the basis of examples and computer simulations. We first address reliability problems in language transcriptions, agreement between transcribers, and how disagreements can be dealt with. We then show that the frequencies of occurrence obtained from a corpus cannot always be analyzed with the traditional X2 test, as corpus data are often not sequentially independent and unit independent. Next, we stress the relevance of the power of statistical tests, and the sizes of statistically significant effects. Finally, we point out that a t-test based on log odds often provides a better alternative to a X2 analysis based on frequency counts.