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PubMed2006

Perception of native and non-native affricate-fricative contrasts: cross-language tests on adults and infants.

Previous studies have shown improved sensitivity to native-language contrasts and reduced sensitivity to non-native phonetic contrasts when comparing 6-8 and 10-12-month-old infants. This developmental pattern is interpreted as reflecting the onset of language-specific processing around the first birthday. However, generalization of this finding is limited by the fact that studies have yielded inconsistent results and that insufficient numbers of phonetic contrasts have been tested developmentally; this is especially true for native-language phonetic contrasts. Three experiments assessed the effects of language experience on affricate-fricative contrasts in a cross-language study of English and Mandarin adults and infants. Experiment 1 showed that English-speaking adults score lower than Mandarin-speaking adults on Mandarin alveolo-palatal affricate-fricative discrimination. Experiment 2 examined developmental change in the discrimination of this contrast in English- and Mandarin-leaning infants between 6 and 12 months of age. The results demonstrated that native-language performance significantly improved with age while performance on the non-native contrast decreased. Experiment 3 replicated the perceptual improvement for a native contrast: 6-8 and 10-12-month-old English-learning infants showed a performance increase at the older age. The results add to our knowledge of the developmental patterns of native and non-native phonetic perception.

Acoustic Stimulation↗
PubMed1980

Stimulus dominance in fused dichotic syllables: trouble for the category goodness hypothesis.

Repp [J. Acoust. Soc. Am. 60, 456-469 (1976)] hypothesized that dichotic stimulus dominance relationships between fused speech sounds reflect the relative category goodness of the competing stimuli, i.e., their relative perceptual distances from the listener's linguistic category prototypes. In experiment I, 15 synthetic syllables from a /bae/-/dae/-/gae) continuum were dichotically fused with three selected stimuli from the same continuum and presented to listeners for identification. Stimuli in the vicinity of phonetic category boundaries were found to make weaker dichotic competitors than stimuli from well within a phonetic category, as predicted. However, some systematic deviations from the predictions and large individual differences were noted. In experiment II, synthetic syllables from a /ba/-/da/-/ga/ continuum were paired with either of the two endpoint stimuli (/ba/,/ga/) in dichotic or mixed presentation. The resulting fused hybrid stimuli were presented in identification and AXB discrimination tests. The hybrids were perceived quite categorically, and there was little difference between dichotic and mixed modes of presentation. These results did not replicate earlier data [Repp, Haskins SR-45/46, 123-139 (1976)] that had suggested that discrimination of dichotic hybrid stimuli might be based on a level of representation preceding phonetic categorization. The category goodness hypothesis, which implies such a level, was neither supported nor contradicted. In experiment III, the prediction was tested that increasing the aspiration amplitude of a /ta/ syllable, and thus its category goodness, would increase the perceptual dominance of this stimulus over a /da/ simultaneously presented to the other ear. This hypothesis was not supported by the data. Rather, the response pattern suggested that a listener's success in perceptually integrating the aspiration noise (of /ta/) with the fused vocalic portion (of /da/ and /ta/) into a single phonetic percept depended on the perceived spatial locations of these stimulus portions. Taken together, the results of the three experiments cast doubt on the category goodness hypothesis and suggest that dichotic stimulus dominance in fused speech sounds is determined by psychoacoustic factors, some as yet undefined.

Acoustic Stimulation↗
PubMed1997

Predicting developmental shifts in perceptual weighting schemes.

Recent models of developmental changes in speech perception suggest that the weights assigned to acoustic properties change as children gain experience with a native language. Empirical evidence supports this position, but few suggestions have been offered as to what guides this shift. These three experiments were designed to improve our ability to predict how perceptual weighting schemes change with development. The specific hypothesis explored was twofold: (1) the weight assigned by adults to any one acoustic property differs across phonetic environments according to how informative that property is in each environment; and (2) the weight assigned by children to any one acoustic property differs less across phonetic environments because children have not fully learned the patterns of covariation between phonetic informativeness and environment for each property. Experiment 1 replicated previous findings of age-related differences in the weights assigned to noise spectra and formant transitions in labeling of syllable-initial fricatives (/s/ or /[symbol: see text]/). In experiment 2 the variation in F3-onset frequency associated with place of fricative constriction was eliminated. This property differs more (i.e., is more informative) in /u/ than in /a/. Accordingly adults' transition effect was reduced more for /u/ than for /a/ from experiment 1. Children's transition effect was similarly reduced across vowel environments. In experiment 3, F3-onset frequency was appropriately manipulated for both vowels, and adults transition effect increased more for /u/ than for /a/ from experiment 2. The increase in children's transition effect was more similar across vowels. We conclude that the children had not fully learned how information provided by F3 transitions varies across /a/ and /u/ environments, and suggest that developmental weighting shifts may be guided by children learning the relation between phonetic informativeness and environment.

Adult↗
PubMed1997

The characteristics of voicing in syllable-initial fricatives in American English.

This study investigated the acoustic characteristics of voicing in the production of fricative consonants. The fricatives [f v s z] were used in combination with the vowels [i e a o u] to create CV syllables, which were produced by four subjects both in a context condition (following voiced and voiceless velar stops) and in isolation. Analyses were conducted of the time course of glottal excitation during the fricative noise interval in the voiced and voiceless fricative stimuli. Results showed that the patterns of voicing in the fricative noise interval were influenced by the voicing characteristics of preceding stop consonants. Nonetheless, these carryover coarticulatory effects were short-lived, influencing only the first 10's of ms of the following segment. Despite the influence of phonetic context on the patterns of voicing, an acoustic measure relating to the presence or absence of glottal excitation at the acoustic boundaries of the fricative noise reliably classified a majority (93%) of the fricative consonants in terms of the phonetic category of voicing. Thus, while phonetic context affected the patterns of glottal excitation in the fricative noise interval, it did not affect the criterial attribute associated with the phonetic category of voicing.

Adult↗
PubMed1999

Recognition of spoken words by native and non-native listeners: talker-, listener-, and item-related factors.

In order to gain insight into the interplay between the talker-, listener-, and item-related factors that influence speech perception, a large multi-talker database of digitally recorded spoken words was developed, and was then submitted to intelligibility tests with multiple listeners. Ten talkers produced two lists of words at three speaking rates. One list contained lexically "easy" words (words with few phonetically similar sounding "neighbors" with which they could be confused), and the other list contained lexically "hard" words (words with many phonetically similar sounding "neighbors"). An analysis of the intelligibility data obtained with native speakers of English (experiment 1) showed a strong effect of lexical similarity. Easy words had higher intelligibility scores than hard words. A strong effect of speaking rate was also found whereby slow and medium rate words had higher intelligibility scores than fast rate words. Finally, a relationship was also observed between the various stimulus factors whereby the perceptual difficulties imposed by one factor, such as a hard word spoken at a fast rate, could be overcome by the advantage gained through the listener's experience and familiarity with the speech of a particular talker. In experiment 2, the investigation was extended to another listener population, namely, non-native listeners. Results showed that the ability to take advantage of surface phonetic information, such as a consistent talker across items, is a perceptual skill that transfers easily from first to second language perception. However, non-native listeners had particular difficulty with lexically hard words even when familiarity with the items was controlled, suggesting that non-native word recognition may be compromised when fine phonetic discrimination at the segmental level is required. Taken together, the results of this study provide insight into the signal-dependent and signal-independent factors that influence spoken language processing in native and non-native listeners.

Adult↗
PubMed1994

Cross-language differences in phonological acquisition: Swedish and American /t/.

Our understanding of phonological acquisition has benefited immensely from cross-linguistic investigations which allow researchers to separate biological and learned factors. To date, most cross-linguistic studies have focused either on differences in phonetic inventories or on differences in frequency of occurrence of particular phonetic and phonological properties in the adult language. This paper describes a third type of study: comparisons of segments that occur in two (or more) languages but differ in their phonetic properties. We present perceptual and acoustic analyses of adult and child productions of word-initial alveolar /t/ in American English and dental /t/ in Swedish. Results showed that listeners' perception of place of articulation was strongly associated with language (alveolar: American English, dental: Swedish) for both adult and child tokens, and was effective in assigning individual speakers to language groups. Three acoustic measures, voice onset time, burst intensity and burst spectral diffuseness correlated with language for both child and adult tokens; the latter two measures correlated with perception as well. The findings suggest that American and Swedish children at 30 months of age have acquired some language-specific phonetic aspects of /t/ phonemes.

Cross-Cultural Comparison↗
PubMedDate not supplied

EEG power spectra of adolescent poor readers.

EEG power spectra were studied in two poor-reading adolescent groups (dysphonetic and phonetic) as the students viewed strings of letters and easy words (seven categories). The students ranged in age from 12 to 16 years; 29 were male, 9 were female. Bilateral results are reported from frontal, parietal, and occipital regions. Significant Group x Hemisphere effects were found in the alpha and beta bands, with the phonetic group showing right greater than left asymmetry. This finding was interpreted to reflect more circumscribed and mature processing in the phonetically abler poor readers, given that normally reading adults typically show right greater than left asymmetry in word tasks. Overall, the dysphonetic group had higher beta power than the phonetic group, which may reflect greater effort.

Adolescent↗
PubMedDate not supplied

Base-language effects on word identification in bilingual speech: evidence from categorical perception experiments.

The categorical perception paradigm was used to investigate whether French-English bilinguals categorize a code-switched word as French or English on the basis of its acoustic-phonetic information alone or whether they are influenced by the base-language context in which the word occurs, that is, by the language in which the majority of words are spoken. Subjects identified stimuli from computer-edited series that ranged from an English to a French word as either the English or the French endpoint. The stimuli were preceded by either an English or a French context sentence. In accord with previous studies (Grosjean, 1988), it was found that the base language had a contrastive effect on the perception of a code-switched word when the endpoints of the between-language series were phonetically marked as English and French, respectively. When the endpoints of the series were phonetically unmarked and thus compatible with either language, however, no effect of the base language was found; in particular, we failed to find the assimilative effect that has been observed with other paradigms (Grosjean, 1988; Soares and Grosjean, 1984; Macnamara and Kushnir, 1971). The current results provide confirming evidence that the perception of a code-switched word is influenced by the base-language context in which it occurs and, moreover, that the nature of the effect depends on the acoustic-phonetic characteristics of the code-switched word. In addition, the finding that a contrastive effect occurs across all paradigms used to date, but that an assimilative effect occurs in only some paradigms, suggests that these two context effects may arise at different stages of processing.

Humans↗
PubMedDate not supplied

Extrapolating from spoken to signed prosody via laboratory phonology.

Laboratory phonology tests the predictions of phonological analyses through experimental investigations of phonetic behavior. This paper describes how a laboratory phonologist might investigate three issues in the analysis of the prosody of signed languages: the internal structure, if any, of the signed syllable, the realization of lexical and phrasal prominence, and the marking of edges. The paper proposes to investigate the internal structure of the syllable by adapting a variety of psycholinguistic techniques that have been extensively used to study the phonetic packaging of phonological material in spoken languages. Phonological and phonetic arguments are presented in support of the hypothesis that signed languages will increase movement kinematics to convey phrasal and perhaps lexical prominence, and an experiment is sketched that would test this hypothesis. Finally, the paper suggests that the experimental study of the edges of sign articulations might allow a clearer choice between competing phonetic and phonological accounts of external sandhi in language in general.

Humans↗
PubMed1995

Circadian differences in hemisphere-linked spelling proficiencies.

Male and female adolescents (N = 113) were assigned randomly to spelling instruction in either morning or afternoon groups for a school year. A spelling list (100 words) was administered at the beginning of the school year to obtain a sample of error responses and estimate proficiency. Although equally proficient, subjects tested in the afternoon showed more phonetically inappropriate errors, while those tested in the morning showed more phonetically appropriate errors. This error pattern is viewed as support for a more engaged left hemisphere in the morning. There were no differences on two types of visual errors. Subjects then received instruction in spelling for nine months in either morning or afternoon settings. Time-of-day effects were not evident on the word list and there were too few errors to conduct a posttest error analysis. However, standardized test results for a subgroup revealed that subjects receiving morning instruction made greater gains on phonetically regular words compared to phonetically irregular words--an effect consistent with a circadian-linked higher level of left hemisphere engagement early in the day. The findings are of a pilot nature, but implications for education and further research are discussed.

Achievement↗
PubMed2002

Stimulus-based lexical distinctiveness as a general word-recognition mechanism.

Word recognition is generally assumed to be achieved via competition in the mental lexicon between phonetically similar word forms. However, this process has so far been examined only in the context of auditory phonetic similarity. In the present study, we investigated whether the influence of word-form similarity on word recognition holds in the visual modality and with the patterns of visual phonetic similarity. Deaf and hearing participants identified isolated spoken words presented visually on a video monitor. On the basis of computational modeling of the lexicon from visual confusion matrices of visual speech syllables, words were chosen to vary in visual phonetic distinctiveness, ranging from visually unambiguous (lexical equivalence class [LEC] size of 1) to highly confusable (LEC size greater than 10). Identification accuracy was found to be highly related to the word LEC size and frequency of occurrence in English. Deaf and hearing participants did not differ in their sensitivity to word LEC size and frequency. The results indicate that visual spoken word recognition shows strong similarities with its auditory counterpart in that the same dependencies on lexical similarity and word frequency are found to influence visual speech recognition accuracy. In particular, the results suggest that stimulus-based lexical distinctiveness is a valid construct to describe the underlying machinery of both visual and auditory spoken word recognition.

Adult↗
PubMed1997

What the reader's eye tells the mind's ear: silent reading activates inner speech.

Although copious research has investigated the role of phonology in reading, little research has investigated the precise nature of the entailed speech representations. The present study examined the similarity of "inner speech" in reading to overt speech. Two lexical decision experiments (in which participants gave speeded word/nonword classifications to letter strings) assessed the effects of implicit variations in vowel and word-initial consonant length. Responses were generally slower for phonetically long stimuli than for phonetically short stimuli, despite equal orthographic lengths. Moreover, the phonetic length effects displayed principled interactions with common factors known to affect lexical decisions, such as word frequency and the similarity of words to nonwords. Both phonetic length effects were stronger among slower readers. The data suggest that acoustic representations activated in silent reading are best characterized as inner speech rather than as abstract phonological codes.

Humans↗
PubMed1992

Discrimination tests of visually influenced syllables.

In the McGurk effect, perception of audiovisually discrepant syllables can depend on auditory, visual, or a combination of audiovisual information. Under some conditions, visual information can override auditory information to the extent that identification judgments of a visually influenced syllable can be as consistent as for an analogous audiovisually compatible syllable. This might indicate that visually influenced and analogous audiovisually compatible syllables are phonetically equivalent. Experiments were designed to test this issue using a compelling visually influenced syllable in an AXB matching paradigm. Subjects were asked to match an audio syllable/va/either to an audiovisually consistent syllable (audio/va/-video/fa/) or an audiovisually discrepant syllable (audio/ba/-video/fa/). It was hypothesized that if the two audiovisual syllables were phonetically equivalent, then subjects should choose them equally often in the matching task. Results show, however, that subjects are more likely to match the audio/va/ to the audiovisually consistent/va/, suggesting differences in phonetic convincingness. Additional experiments further suggest that this preference is not based on a phonetically extraneous dimension or on noticeable relative audiovisual discrepancies.

Adult↗
PubMed2000

Effects of training on attention to acoustic cues.

Learning new phonetic categories in a second language may be thought of in terms of learning to focus one's attention on those parts of the acoustic-phonetic structure of speech that are phonologically relevant in any given context. As yet, however, no study has demonstrated directly that training can shift listeners' attention between acoustic cues given feedback about the linguistic phonetic category alone. In this paper we discuss the results of a training study in which subjects learned to shift their attention from one acoustic cue to another using only category-level identification as feedback. Results demonstrate that training redirects listeners' attention to acoustic cues and that this shift of attention generalizes to novel (untrained) phonetic contexts.

Adolescent↗
PubMed1995

Three- and four-year-olds' perceptual confusions for spoken words.

Although infants have the ability to discriminate a variety of speech contrasts, young children cannot always use this ability in the service of spoken-word recognition. The research reported here asked whether the reason young children sometimes fail to discriminate minimal word pairs is that they are less efficient at word recognition than adults, or whether it is that they employ different lexical representations. In particular, the research evaluated the proposal that young children's lexical representations are more "holistic" than those of adults, and are based on overall acoustic-phonetic properties, as opposed to phonetic segments. Three- and four-year-olds were exposed initially to an invariant target word and were subsequently asked to determine whether a series of auditory stimuli matched or did not match the target. The critical test stimuli were nonwords that varied in their degree of phonetic featural overlap with the target, as well as in terms of the position(s) within the stimuli at which they differed from the target, and whether they differed from the target on one or two segments. Data from four experiments demonstrated that the frequency with which children mistook a nonword stimulus for the target was influenced by extent of featural overlap, but not by word position. The data also showed that, contrary to the predictions of the holistic hypothesis, stimuli differing from the target by two features on a single segment were confused with the target more often than were stimuli differing by a single feature on each of two segments. This finding suggests that children use both phonetic features and segments in accessing their mental lexicons, and that they are therefore much more similar to adults than is suggested by the holistic hypothesis.

Attention↗
PubMed1992

[Processing steps in perception of speech sounds].

The aim of this study is to investigate whether speech sounds--as is stated by the widely accepted theory of categorical perception of speech--can be perceived only as instances of phonetic categories, or whether physical differences between speech sounds lead to perceptual differences regardless of their phonetic categorization. Subjects listened to pairs of synthetically generated speech sounds that correspond to realizations of the syllables "ba" and "pa" in natural German, and they were instructed to decide as fast as possible whether they perceived them as belonging to the same or to different phonetic categories. For 'same'-responses reaction times become longer when the physical distance between the speech sounds is increased; for 'different'-responses reaction times become shorter with growing physical distance between the stimuli. The results show that subjects can judge speech sounds on the basis of perceptual continua, which is inconsistent with the theory of categorical perception. A mathematical model is presented that attempts to explain the results by postulating two interacting stages of processing, a psychoacoustical and a phonetic one. The model is not entirely confirmed by the data, but it seems to deserve further consideration.

Adult↗
PubMed1996

Speech perception of temporally reversed syllables by normally hearing adults.

BACKGROUND: The general purpose of this study was to determine the effects of phonological knowledge on performance on a simple task of speech discrimination. If a test can be devised that is independent of the subject's phonological knowledge then it should be possible to measure auditory speech perception capacity in young deaf children before they have developed spoken language skills. In the present study, temporal reversal was used to limit normal subjects' use of phonological knowledge without removing acoustic information. METHODS: An auditory, 3-interval, forced-choice (oddity) test of phonetic contrast perception was administered to 5 normally hearing adult speakers of English. Perception of place of articulation was measured in stops and fricatives--both voiced and unvoiced. The test was presented both with natural syllables and with the same syllables reversed in time. In addition, the test was administered with a fixed context and a mixed context (i.e., context changing from trial to trial). The subject's task was always to identify the odd-man-out in each presentation of 3 syllables. RESULTS: Overall, error rate was significantly higher for temporally-reversed than for natural syllables (6.7% versus 1.7%). The effect was, however, present only in stops (11.7% versus 1.7%) and not in fricatives (0.8% versus 0.8%). Changing from a fixed to a mixed context did not influence the effect of reversal. There were, however, significant differences among subjects in the temporally-reversed condition. CONCLUSIONS: The main effect of reversal supports the hypothesis that performance falls, even on a simple task, when phonetic processing is impeded. The fact that the effect is present only for stops adds further support, because temporal reversal does not affect the essential acoustic properties of fricatives. The presence of inter-subject differences suggests that the ability to switch to an acoustic strategy when phonetic processing is impeded may be affected by aptitude and experience. The fact that error rate was low, even for reversed stops, suggests that a test of this type could be used for assessing speech perception capacity in deaf children with impaired phonology. The procedure is not, however, completely independent of the effects of phonetic processing.

Adult↗
PubMed2001

Chinese Children's Incidental Learning of Word Meanings.

We investigated the effects of metalinguistic awareness and the internal structure of Chinese characters on children's incidental learning of word meanings while reading. The participants were 241 Taiwanese children from six fourth-grade classes. They were randomly assigned to read one of two texts, and then their knowledge of unfamiliar characters from both texts was assessed. Two kinds of factors that might influence incidental learning of character meanings were examined: features of the unfamiliar characters (radical helpfulness, phonetic regularity, and contextual support) and child characteristics (radical awareness, phonetic awareness, general vocabulary, and prior knowledge of target characters). Results showed that children could incidentally learn characters during normal reading. Children who had more radical or phonetic awareness knew more characters, especially when the character contained a radical that gave a clue to meaning. However, contrary to expectation, radical helpfulness and phonetic regularity did not contribute to character learning. Characters were easier to learn when contextual support was strong. Copyright 2001 Academic Press.

Journal Article↗