元音范畴知觉中特征分析和整合的时间进程

采用启动范式,在三个实验中通过操纵启动音和目标音的频谱相似度和时间间隔,考察了汉语听者元音范畴知觉中特征分析和整合的时间进程。结果发现随着启动音（从纯音、复合音到目标元音本身）和目标元音频谱相似度的增加,启动效应延续的时间越来越长。实验结果支持语音范畴知觉存在早期的声学特征分析和整合到后期的范畴知觉阶段,并为这些加工阶段的时间进程提供了初步的证据。     

Effects of time-order, interstimulus interval, and feedback in duration discrimination of noise bursts in the 50- and 1000-ms ranges

Participants compared durations of paired white-noise bursts, with interstimulus interval (ISI) 100, 300, 900, or 2700 ms, presented in the order standard (St)-comparison (Co) or Co-St. St was 50 or 1000 ms, and 75% difference thresholds for "longer" and "shorter" judgments were estimated. In Experiment 1 feedback was given; in Experiment 2, with ISIs 900 and 2700 ms, there was no feedback. For St=1000 ms, the just noticeable difference (JND) in noise duration was generally smaller with the order St-Co than with Co-St; for St=50 ms, the JND relation was the opposite. JNDs increased with shorter ISIs. Time-order errors were positive for St=50 ms and negative for St=1000 ms, and approached zero for longer ISIs. Using Hellstr?m's sensation-weighting (SW) model, the ratio of the stimulus weights for the first and second burst was estimated; this ratio was generally >1 for St=50 ms and <1 for St=1000 ms. JNDs were smaller with feedback than without; the greatest reduction was found for St=1000 ms and an ISI of 2700 ms with the order Co-St, possibly because feedback increased participants' attention to the first stimulus. These results demonstrate the sensitivity of discrimination measures for long as well as brief durations to the factors of ISI, presentation order, and feedback. They also suggest different modes of stimulus processing for short and long durations.     

Changes in infant directed speech in the first six months

The Mother–Infant Phonetic Interaction model (MIPhI) predicts that, compared with adult directed speech (ADS), in infant directed speech (IDS) vowels will be overspecified and consonants underspecified during the infants' first 6 months. In a longitudinal natural study, six mothers' ADS and IDS were recorded on 10 occasions during the first 6 months after their infants were born. Acoustic–phonetic measures, including the first two formant frequencies and duration for vowels and the duration of the fricative /s/, were used to test the MIPhI model with differences between IDS and ADS during the infants' first 6 months. Repeated measures analyses showed the fricative /s/ duration was stably longer in IDS, corresponding to an overspecification throughout the 6 months. The unexpected smaller vowel space for IDS than ADS was stably maintained over the six months, suggesting an underspecification of vowels. Vowel duration, which was generally longer in IDS than ADS, however, changed over time, decreasing in difference between IDS and ADS during month 3 and 4. Results invite adjustments to the MIPhI model, in particular related to infants' needs for perceptual enhancement of speech segments, and to the course of infant neurological and communicative development throughout the first 6 months. Copyright © 2006 John Wiley & Sons, Ltd.     

Cross-modal speech perception in adults and infants using nonspeech auditory stimuli.

Adults and infants were tested for the capacity to detect correspondences between nonspeech sounds and real vowels. The /i/ and /a/ vowels were presented in 3 different ways: auditory speech, silent visual faces articulating the vowels, or mentally imagined vowels. The nonspeech sounds were either pure tones or 3-tone complexes that isolated a single feature of the vowel without allowing the vowel to be identified. Adults perceived an orderly relation between the nonspeech sounds and vowels. They matched high-pitched nonspeech sounds to /i/ vowels and low-pitched nonspeech sounds to /a/ vowels. In contrast, infants could not match nonspeech sounds to the visually presented vowels. Infants' detection of correspondence between auditory and visual speech appears to require the whole speech signal; with development, an isolated feature of the vowel is sufficient for detection of the cross-modal correspondence.     

Influence of vowel context on the audio‐visual speech perception of voiced stop consonants

The work reported here investigated whether the extent of McGurk effect differs according to the vowel context, and differs when cross‐modal vowels are matched or mismatched in Japanese. Two audio‐visual experiments were conducted to examine the process of audio‐visual phonetic‐feature extraction and integration. The first experiment was designed to compare the extent of the McGurk effect in Japanese in three different vowel contexts. The results indicated that the effect was largest in the /i/ context, moderate in the /a/ context, and almost nonexistent in the /u/ context. This suggests that the occurrence of McGurk effect depends on the characteristics of vowels and the visual cues from their articulation. The second experiment measured the McGurk effect in Japanese with cross‐modal matched and mismatched vowels, and showed that, except with the /u/ sound, the effect was larger when the vowels were matched than when they were mismatched. These results showed, again, that the extent of McGurk effect depends on vowel context and that auditory information processing before phonetic judgment plays an important role in cross‐modal feature integration.     

Auditory enhancement and the perception of concurrent vowels

Listeners identified both constituents of double vowels created by summing the waveforms of pairs of synthetic vowels with the same duration and fundamental frequency. Accuracy of identification was significantly above chance. Effects of introducing such double vowels by visual or acoustical precursor stimuli were examined. Precursors specified the identity of one of the two constituent vowels. Performance was scored as the accuracy with which the other vowel was identified. Visual precursors were standard English spellings of one member of the vowel pair; acoustical precursors were 1-sec segments of one member of the vowel pair. Neither visual precursors nor contralateral acoustical precursors improved performance over the condition with no precursor. Thus, knowledge of the identity of one of the constituents of a double vowel does not help listeners to identify the other constituent. A significant improvement in performance did occur with ipsilateral acoustical precursors, consistent with earlier demonstrations that frequency components which undergo changes in spectral amplitude achieve enhanced auditory prominence relative to unchanging components. This outcome demonstrates the joint but independent operation of auditory and perceptual processes underlying the ability of listeners to understand speech despite adversely peaked frequency responses in communication channels.     

Call me Alix,not Elix: vowels are more important than consonants in own‐name recognition at 5 months

Consonants and vowels differ acoustically and articulatorily, but also functionally: Consonants are more relevant for lexical processing, and vowels for prosodic/syntactic processing. These functional biases could be powerful bootstrapping mechanisms for learning language, but their developmental origin remains unclear. The relative importance of consonants and vowels at the onset of lexical acquisition was assessed in French‐learning 5‐month‐olds by testing sensitivity to minimal phonetic changes in their own name. Infants’ reactions to mispronunciations revealed sensitivity to vowel but not consonant changes. Vowels were also more salient (on duration and intensity) but less distinct (on spectrally based measures) than consonants. Lastly, vowel (but not consonant) mispronunciation detection was modulated by acoustic factors, in particular spectrally based distance. These results establish that consonant changes do not affect lexical recognition at 5 months, while vowel changes do; the consonant bias observed later in development does not emerge until after 5 months through additional language exposure.     

Speeded detection of vowels: A cross-linguistic study

In four experiments, listeners’ response times to detect vowel targets in spoken input were measured. The first three experiments were conducted in English. In two, one using real words and the other, nonwords, detection accuracy was low, targets in initial syllables were detected more slowly than targets in final syllables, and both response time and missed-response rate were inversely correlated with vowel duration. In a third experiment, the speech context for some subjects included all English vowels, while for others, only five relatively distinct vowels occurred. This manipulation had essentially no effect, and the same response pattern was again observed. A fourth experiment, conducted in Spanish, replicated the results in the first three experiments, except that miss rate was here unrelated to vowel duration. We propose that listeners’ responses to vowel targets in naturally spoken input are effectively cautious, reflecting realistic appreciation of vowel variability in natural context.     

Neural processing of acoustic duration and phonological German vowel length: Time courses of evoked fields in response to speech and nonspeech signals

Recent experiments showed that the perception of vowel length by German listeners exhibits the characteristics of categorical perception. The present study sought to find the neural activity reflecting categorical vowel length and the short-long boundary by examining the processing of non-contrastive durations and categorical length using MEG. Using disyllabic words with varying /a/-durations and temporally-matched nonspeech stimuli, we found that each syllable elicited an M50/M100-complex. The M50-amplitude to the second syllable varied along the durational continuum, possibly reflecting the mapping of duration onto a rhythm representation. Categorical length was reflected by an additional response elicited when vowel duration exceeded the short-long boundary. This was interpreted to reflect the integration of an additional timing unit for long in contrast to short vowels. Unlike to speech, responses to short nonspeech durations lacked a M100 to the first and M50 to the second syllable, indicating different integration windows for speech and nonspeech signals.     

An acoustic study of vowel production in aphasia

A group of five anterior and seven posterior aphasic patients were recorded for their vowel productions of the nine nondipthong vowels of American English and compared to a group of seven normal speakers. All phonemic substitutions were eliminated from the data base. A Linear Predictive Coding (LPC) computer program was used to extract the first and the second formant frequencies at the midpoint of the vowel for each of the remaining repetitions of the nine vowels. The vowel duration and the fundamental frequency of phonation were also measured. Although there were no significant differences in the formant frequency means across groups, there were significantly larger standard deviations for the aphasic groups compared to normals. Anterior aphasics were not significantly different from posterior aphasics with respect to this greater formant variability. There was a main effect for vowel duration means, but no individual group was significantly different from the other. Standard deviations of duration were significantly greater for the anterior aphasics compared to normal speakers, but not significantly different from posterior aphasics. Posterior aphasics did not have significantly greater standard deviations of duration than did normal subjects. Greater acoustic variability was considered to evidence a phonetic production deficit on the part of both groups of aphasic speakers, in the context of fairly well-preserved phonemic organization for vowels.     

威胁性刺激注意偏向的时间进程

注意偏向各成分间关系及发生时间进程尚存争议。本研究以情绪图片为刺激,采用类别判断任务,通过眼动技术探讨正常个体对威胁性刺激注意偏向的时间进程。结果显示,(1)向左的首次眼跳概率高于向右,而潜伏期短于向右,存在左侧偏向;(2)注意回避发生在250ms以内,解除锁定困难发生在400ms之后;(3)注意偏向影响类别判断过程。结果表明,注意回避与左侧偏向在威胁性刺激注意偏向形成早期存在相互作用,且比解除锁定困难更早发生。     

Timing characteristics of speech after brain damage: vowel length in Thai.

This paper explores the extent of timing deficits in vowels produced by brain-damaged speakers of a language with a phonological contrast in vowel length. Short and long vowels in Thai were produced in isolated monosyllabic words by 20 normal adults, 14 right hemisphere patients, and 17 left hemisphere aphasics. Vowel durations were measured spectrographically. Although the phonological contrast was relatively preserved, as indicated by average duration, a subtle timing deficit in vowels produced by nonfluent aphasics was indicated by a compressed duration continuum and increased variability in vowel production.     

Categorical perception: effects of the extent and rate of spectral change

ABSTRACT

Two experiments evaluated a potential explanation of categorical perception (CP) for place of articulation – namely, that listeners derive limited information from rapid spectral changes. Experiment 1 examined vowel context effects for /b/–/d/ continua that included consonant–vowel tokens with F2 onset frequencies that varied systematically from the F2 frequencies of their corresponding steady-states. Phoneme categorisation sharply shifted with F2 direction at locations along the continuum where discrimination performance peaked, indicating CP. Experiment 2 compared findings for a replicated condition against conditions with vowels reduced to match consonant duration or consonants extended to match vowels. CP was similarly obtained for replicated and vowel-reduced conditions. However, listeners frequently perceived diphthongs centrally on the consonant-extended continuum. Some listeners demonstrated CP, although aggregate performance appeared more continuous. These experiments indicate a model based upon the perceived direction of frequency transitions.     

When infants talk,infants listen: pre‐babbling infants prefer listening to speech with infant vocal properties

To learn to produce speech, infants must effectively monitor and assess their own speech output. Yet very little is known about how infants perceive speech produced by an infant, which has higher voice pitch and formant frequencies compared to adult or child speech. Here, we tested whether pre‐babbling infants (at 4–6 months) prefer listening to vowel sounds with infant vocal properties over vowel sounds with adult vocal properties. A listening preference favoring infant vowels may derive from their higher voice pitch, which has been shown to attract infant attention in infant‐directed speech (IDS). In addition, infants' nascent articulatory abilities may induce a bias favoring infant speech given that 4‐ to 6‐month‐olds are beginning to produce vowel sounds. We created infant and adult /i/ (‘ee’) vowels using a production‐based synthesizer that simulates the act of speaking in talkers at different ages and then tested infants across four experiments using a sequential preferential listening task. The findings provide the first evidence that infants preferentially attend to vowel sounds with infant voice pitch and/or formants over vowel sounds with no infant‐like vocal properties, supporting the view that infants' production abilities influence how they process infant speech. The findings with respect to voice pitch also reveal parallels between IDS and infant speech, raising new questions about the role of this speech register in infant development. Research exploring the underpinnings and impact of this perceptual bias can expand our understanding of infant language development.     

Differential vowel duration associated with children's word-final fricative deletion.

This study assessed whether 3 children, 5 to 6 years old, who deleted word-final fricatives preserve the voicing contrast for those fricatives by producing dif ferential duration of the preceding vowel. The children's CV syllable productions were compared to their CV(C) syllable productions in which the final consonant was intended but actually deleted. Analysis indicated that all 3 children exhibited significantly longer vowel duration, in CV syllables than in CV(C) syllables. This differential duration of the preceding vowel was shown in both isolation and carrier phrase conditions. Of the 3 children 2 preserved the voicing contrast by showing significantly longer vowels preceding voiced consonants as compared to voiceless consonants. One child did this in both isolation and carrier phrase conditions and the other child did this in isolation only. All 3 children manipulated vowel duration to signify the linguis tic contrast, therefore these findings support a linguistic perspective of speech development which focuses on the acquisition and knowledge of the linguistic rules of the language. In addition, the large amount of variability in vowel duration for CV and CV(C) syllables and the marked variability in performance across children support a biological view of a developing vocal tract undergoing structural and physiological changes.     

Acoustic and phonological factors in vowel identification

Vowels are better identified in a consonantal syllabic context than as isolated vowels. This finding is contrary to predictions from traditional theories of vowel perception. The poor perception of isolated vowels might be attributed to a lack of dynamic acoustic cues or to familiarity effects related to the phonological rules of English. Vowel identification tests were conducted using six talkers, nine vowels, and seven syllabic contexts. Consonantal context improved vowel identification; final consonants aided identification more than initial consonants. No consistent support was found for the effect of phonological rules but duration information was seen to play a critical role. Results constitute a challenge to traditional theories of vowel perception.     

Vowel categorization skill and its relationship to early literacy skills among first-grade Québec-French children

Six-year-old children's ability to categorize words on the basis of vowel categories was examined at the beginning of first grade and again after 6 months of formal schooling. The potential effects of relative proximity of vowels in the vowel space, of syllable structure, and of input phonology were assessed. Also, the effect of literacy instruction on vowel categorization and the relationship of vowel categorization with vowel spelling and reading skill were investigated. Results indicate that the ability to categorize vowels does not develop uniformly but is affected by the degree of spectral/articulatory proximity between vowels, by syllable structure, and potentially by characteristics of the input phonology. Error analyses further indicate that children have fuzzy category boundaries between vowels adjacent on the height continuum. The pattern of results on oral categorization and written tasks suggests a reciprocal relationship. Categorization ability improved after 6 months of schooling. However, vowels that children found more difficult to categorize were also more difficult to read and spell.     

Precategorical acoustic storage for vowels of short and long duration

Ss gave immediate ordered recall for series of seven isolated vowel sounds from a vocabulary of three-/a, u, i/. In a 2 by 2 design, the stimulus vowels were either 50 or 300 msec in duration (though always presented at a 2/sec rate), and the seven-item series was followed by either a nonverbal recall cue or a verbal recall cue that is a stimulus suffix. There was an interaction such that the recall impairment caused by the verbal suffix was larger when the stimulus items were vowels of long duration than when they were vowels of short duration. Since short vowels tend to be more categorically perceived than long vowels, this result reinforces the view that vowels and stop consonants are differently represented in auditory short-term memory for reasons that have to do with the way m winch they are perceived or vice versa.     

Pigeons' memory for number of events: Effects of intertrial interval and delay interval illumination

In Experiment 1, pigeons were trained at a 0-s baseline delay to discriminate sequences of light flashes (illumination of the feeder) that varied in number but not time (2f/4s and 8f/4s). During training, the intertrial interval was illuminated by the houselight for Group Light, but it was dark for Group Dark. Testing conducted with dark delay intervals produced a strong choose-small bias in both groups. All birds then received baseline training with a 5-s dark delay and were subsequently tested at shorter and longer dark delays. A choose-small bias was again observed at delays longer than the training delay, while a choose-large bias occurred at delays shorter than the training delay. Differentiating the ambient chamber illumination during the intertrial interval and the delay interval did not attenuate choose-small or choose-large effects. In Experiment 2, all birds received baseline training with a 5-s illuminated delay and were subsequently tested at shorter and longer illuminated delays. A choose-large bias was observed at delays longer than the training delay, while a choose-small bias occurred at delays shorter than the training delay. In Experiment 3, on intermittent test trials, when the duration of the second flash on small-sample trials was equal to the total flash duration on large-sample trials (i.e., 1600 ms), accuracy fell to approximately chance. These results suggest that pigeons discriminated the sequences of light flashes that varied in number but not in total duration of the sequence by relying on other temporal properties of the sequence rather than by using an event switch to count flashes.