Comprehension Dept Publications

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

Three eye-tracking experiments tested at what processing stage lexically-guided retuning of a fricative contrast affects perception. One group of participants heard an ambiguous fricative between /s/ and /f/ replace /s/ in s-final words, the other group heard the same ambiguous fricative replacing /f/ in f-final words. In a test phase, both groups of participants heard a range of ambiguous fricatives at the end of Dutch minimal pairs (e.g., roos-roof, ‘rose’-‘robbery’). Participants who heard the ambiguous fricative replacing /f/ during exposure chose at test the f-final words more often than the other participants. During this test-phase, eye-tracking data showed that the effect of exposure exerted itself as soon as it could possibly have occurred, 200 ms after the onset of the fricative. This was at the same time as the onset of the effect of the fricative itself, showing that the perception of the fricative is changed by perceptual learning at an early level. Results converged in a time-window analysis and a Jackknife procedure testing the time at which effects reached a given proportion of their maxima. This indicates that perceptual learning affects early stages of speech processing, and supports the conclusion that perceptual learning is indeed perceptual rather than post-perceptual.

Abstract

Cross-language differences in the use of coarticulatory cues for the identification of fricatives have been demonstrated in a phoneme detection task: Listeners with perceptually similar fricative pairs in their native phoneme inventories (English, Polish, Spanish) relied more on cues from vowels than listeners with perceptually more distinct fricative contrasts (Dutch and German). The present gating study further investigated these cross-language differences and addressed three questions. (1) Are there cross-language differences in informativeness of parts of the speech signal regarding place of articulation for fricative identification? (2) Are such cross-language differences fricative-specific, or do they extend to the perception of place of articulation for plosives? (3) Is such language-specific uptake of information based on cues preceding or following the consonantal constriction? Dutch, Italian, Polish, and Spanish listeners identified fricatives and plosives in gated CV and VC syllables. The results showed cross-language differences in the informativeness of coarticulatory cues for fricative identification: Spanish and Polish listeners extracted place of articulation information from shorter portions of VC syllables. No language-specific differences were found for plosives, suggesting that greater reliance on coarticulatory cues did not generalize to other phoneme types. The language-specific differences for fricatives were based on coarticulatory cues into the consonant.

Abstract

Analysis of a corpus of spontaneously produced Japanese puns from a single speaker over a two-year period provides a view of how a punster selects a source word for a pun and transforms it into another word for humorous effect. The pun-making process is driven by a principle of similarity: the source word should as far as possible be preserved (in terms of segmental sequence) in the pun. This renders homophones (English example: band–banned) the pun type of choice, with part–whole relationships of embedding (cap–capture), and mutations of the source word (peas–bees) rather less favored. Similarity also governs mutations in that single-phoneme substitutions outnumber larger changes, and in phoneme substitutions, subphonemic features tend to be preserved. The process of spontaneous punning thus applies, on line, the same similarity criteria as govern explicit similarity judgments and offline decisions about pun success (e.g., for inclusion in published collections). Finally, the process of spoken-word recognition is word-play-friendly in that it involves multiple word-form activation and competition, which, coupled with known techniques in use in difficult listening conditions, enables listeners to generate most pun types as offshoots of normal listening procedures.

Abstract

Are there bi-directional influences between speech perception and music perception? An answer to this question is essential for understanding the extent to which the speech and music that we hear are processed by domain-general auditory processes and/or by distinct neural auditory mechanisms. This review summarizes a large body of behavioral and neuroscientific findings which suggest that the musical experience of trained musicians does modulate speech processing, and a sparser set of data, largely on pitch processing, which suggest in addition that linguistic experience, in particular learning a tone language, modulates music processing. Although research has focused mostly on music on speech effects, we argue that both directions of influence need to be studied, and conclude that the picture which thus emerges is one of mutual interaction across domains. In particular, it is not simply that experience with spoken language has some effects on music perception, and vice versa, but that because of shared domain-general subcortical and cortical networks, experiences in both domains influence behavior in both domains.

Abstract

The social significance of recognizing the person who talks to us is obvious, but the neural mechanisms that mediate talker identification are unclear. Regions along the bilateral superior temporal sulcus (STS) and the inferior frontal cortex (IFC) of the human brain are selective for voices, and they are sensitive to rapid voice changes. Although it has been proposed that voice recognition is supported by prototype-centered voice representations, the involvement of these category-selective cortical regions in the neural coding of such "mean voices" has not previously been demonstrated. Using fMRI in combination with a voice identity learning paradigm, we show that voice-selective regions are involved in the mean-based coding of voice identities. Voice typicality is encoded on a supra-individual level in the right STS along a stimulus-dependent, identity-independent (i.e., voice-acoustic) dimension, and on an intra-individual level in the right IFC along a stimulus-independent, identity-dependent (i.e., voice identity) dimension. Voice recognition therefore entails at least two anatomically separable stages, each characterized by neural mechanisms that reference the central tendencies of voice categories.

Abstract

In two eye-tracking experiments we examined whether wider discourse information helps
the recognition of reduced pronunciations (e.g., 'puter') more than the recognition of
canonical pronunciations of spoken words (e.g., 'computer'). Dutch participants listened to
sentences from a casual speech corpus containing canonical and reduced target words. Target
word recognition was assessed by measuring eye fixation proportions to four printed words
on a visual display: the target, a "reduced form" competitor, a "canonical form" competitor
and an unrelated distractor. Target sentences were presented in isolation or with a wider
discourse context. Experiment 1 revealed that target recognition was facilitated by wider
discourse information. Importantly, the recognition of reduced forms improved significantly
when preceded by strongly rather than by weakly supportive discourse contexts. This was not
the case for canonical forms: listeners' target word recognition was not dependent on the
degree of supportive context. Experiment 2 showed that the differential context effects in
Experiment 1 were not due to an additional amount of speaker information. Thus, these data
suggest that in natural settings a strongly supportive discourse context is more important for
the recognition of reduced forms than the recognition of canonical forms.

Abstract

The ability to extract word forms from continuous speech is a prerequisite for constructing a vocabulary and emerges in the first year of life. Electrophysiological (ERP) studies of speech segmentation by 9- to 12-month-old listeners in several languages have found a left-localized negativity linked to word onset as a marker of word detection. We report an ERP study showing significant evidence of speech segmentation in Dutch-learning 7-month-olds. In contrast to the left-localized negative effect reported with older infants, the observed overall mean effect had a positive polarity. Inspection of individual results revealed two participant sub-groups: a majority showing a positive-going response, and a minority showing the left negativity observed in older age groups. We retested participants at age three, on vocabulary comprehension and word and sentence production. On every test, children who at 7 months had shown the negativity associated with segmentation of words from speech outperformed those who had produced positive-going brain responses to the same input. The earlier that infants show the left-localized brain responses typically indicating detection of words in speech, the better their early childhood language skills.

Abstract

Vocabularies contain hundreds of thousands of words built from only a handful of phonemes, so that inevitably longer words tend to contain shorter ones. In many languages (but not all) such embedded words occur more often word-initially than word-finally, and this asymmetry, if present, has farreaching consequences for spoken-word recognition. Prior research had ascribed the asymmetry to suffixing or to effects of stress (in particular, final syllables containing the vowel schwa). Analyses of the standard French vocabulary here reveal an effect of suffixing, as predicted by this account, and further analyses of an artificial variety of French reveal that extensive final schwa has an independent and additive effect in promoting the embedding asymmetry.

Abstract

Listeners retune the boundaries between phonetic categories to adjust to individual speakers' productions. Lexical information, for example, indicates what an unusual sound is supposed to be, and boundary retuning then enables the speaker's sound to be included in the appropriate auditory phonetic category. In this study, it was investigated whether lexical knowledge that is known to guide the retuning of auditory phonetic categories, can also retune visual phonetic categories. In Experiment 1, exposure to a visual idiosyncrasy in ambiguous audiovisually presented target words in a lexical decision task indeed resulted in retuning of the visual category boundary based on the disambiguating lexical context. In Experiment 2 it was tested whether lexical information retunes visual categories directly, or indirectly through the generalization from retuned auditory phonetic categories. Here, participants were exposed to auditory-only versions of the same ambiguous target words as in Experiment 1. Auditory phonetic categories were retuned by lexical knowledge, but no shifts were observed for the visual phonetic categories. Lexical knowledge can therefore guide retuning of visual phonetic categories, but lexically guided retuning of auditory phonetic categories is not generalized to visual categories. Rather, listeners adjust auditory and visual phonetic categories to talker idiosyncrasies separately.

Abstract

Recent evidence shows that listeners use abstract prelexical units in speech perception. Using the phenomenon of lexical retuning in speech processing, we ask whether those units are necessarily phonemic. Dutch listeners were exposed to a Dutch speaker producing ambiguous phones between the Dutch syllable-final allophones approximant [r] and dark [l]. These ambiguous phones replaced either final /r/ or final /l/ in words in a lexical-decision task. This differential exposure affected perception of ambiguous stimuli on the same allophone continuum in a subsequent phonetic-categorization test: Listeners exposed to ambiguous phones in /r/-final words were more likely to perceive test stimuli as /r/ than listeners with exposure in /l/-final words. This effect was not found for test stimuli on continua using other allophones of /r/ and /l/. These results confirm that listeners use phonological abstraction in speech perception. They also show that context-sensitive allophones can play a role in this process, and hence that context-insensitive phonemes are not necessary. We suggest there may be no one unit of perception

Abstract

In connected speech, phonological assimilation to neighboring words can lead to pronunciation variants (e.g., 'garden bench'→ "gardem bench"). A large body of literature suggests that listeners use the phonetic context to reconstruct the intended word for assimilation types that often lead to incomplete assimilations (e.g., a pronunciation of "garden" that carries cues for both a labial [m] and an alveolar [n]). In the current paper, we show that a similar context effect is observed for an assimilation that is often complete, Korean labial-to-velar place assimilation. In contrast to the context effects for partial assimilations, however, the context effects seem to rely completely on listeners' experience with the assimilation pattern in their native language.

Abstract

We investigated how the strength of a foreign accent and varying types of experience with foreign-accented speech influence the recognition of accented words. In Experiment 1, native Dutch listeners with limited or extensive prior experience with German-accented Dutch completed a cross-modal priming experiment with strongly, medium, and weakly accented words. Participants with limited experience were primed by the medium and weakly accented words, but not by the strongly accented words. Participants with extensive experience were primed by all accent types. In Experiments 2 and 3, Dutch listeners with limited experience listened to a short story before doing the cross-modal priming task. In Experiment 2, the story was spoken by the priming task speaker and either contained strongly accented words or did not. Strongly accented exposure led to immediate priming by novel strongly accented words, while exposure to the speaker without strongly accented tokens led to priming only in the experiment’s second half. In Experiment 3, listeners listened to the story with strongly accented words spoken by a different German-accented speaker. Listeners were primed by the strongly accented words, but again only in the experiment’s second half. Together, these results show that adaptation to foreign-accented speech is rapid but depends on accent strength and on listener familiarity with those strongly accented words.

Abstract

How does sentential context influence visual word recognition? Recent neural models suggest that single words are recognized via a hierarchy of local combination detectors [1]. Low-level features are extracted first by neurons in V1 in the visual cortex, features are then combined and fed into the higher level of letter
fragments in V2, and then letter shapes in V4, and so on. A recent EEG study examining word recognition in context has shown that contextually-driven anticipation can influence this hierarchy of visual word recognition early on [2]. Specifically, a minor mismatch between the predicted visual word form and the actual input (cake
vs. ceke) can elicit brain responses ~130 ms after word onset [2].

Abstract

Two eye-tracking experiments tested whether native listeners can adapt
to reductions in casual Dutch speech. Listeners were exposed to segmental
([b] > [m]), syllabic (full-vowel-deletion), or no reductions. In a subsequent
test phase, all three listener groups were tested on how efficiently they could
recognize both types of reduced words. In the first Experiment’s exposure
phase, the (un)reduced target words were predictable. The segmental reductions
were completely consistent (i.e., involved the same input sequences).
Learning about them was found to be pattern-specific and generalized in the
test phase to new reduced /b/-words. The syllabic reductions were not consistent
(i.e., involved variable input sequences). Learning about them was
weak and not pattern-specific. Experiment 2 examined effects of word repetition
and predictability. The (un-)reduced test words appeared in the exposure
phase and were not predictable. There was no evidence of learning for
the segmental reductions, probably because they were not predictable during
exposure. But there was word-specific learning for the vowel-deleted words.
The results suggest that learning about reductions is pattern-specific and
generalizes to new words if the input is consistent and predictable. With
variable input, there is more likely to be adaptation to a general speaking
style and word-specific learning.