Simultaneous effects on vowel duration in American English: a covariance structure modeling approach

The powerful techniques of covariance structure modeling (CSM) long have been used to study complex behavioral phenomenon in the social and behavioral sciences. This study employed these same techniques to examine simultaneous effects on vowel duration in American English. Additionally, this study investigated whether a single population model of vowel duration fits observed data better than a dual population model where separate parameters are generated for syllables that carry large information loads and for syllables that specify linguistic relationships. For the single population model, intrinsic duration, phrase final position, lexical stress, post-vocalic consonant voicing, and position in word all were significant predictors of vowel duration. However, the dual population model, in which separate model parameters were generated for (1) monosyllabic content words and lexically stressed syllables and (2) monosyllabic function words and lexically unstressed syllables, fit the data better than the single population model. Intrinsic duration and phrase final position affected duration similarly for both the populations. On the other hand, the effects of post-vocalic consonant voicing and position in word, while significant predictors of vowel duration in content words and stressed syllables, were not significant predictors of vowel duration in function words or unstressed syllables. These results are not unexpected, based on previous research, and suggest that covariance structure analysis can be used as a complementary technique in linguistic and phonetic research.     

Evidence for mora timing in Japanese

Japanese has long been described as a "mora-timed" language by linguists. Japanese pedagogy has traditionally claimed that moras are constant in duration. Four experiments are reported investigating segmental timing in Japanese in order to test several straightforward hypotheses about mora timing. First, it is demonstrated that words with an increasing number of moras increase in duration by nearly constant increments. The next two experiments explored the mechanisms by which constant mora durations are achieved given that there are large universal differences in the inherent duration of various segment types (e.g., /u/vs/a/), and given that some syllables are supposed to be two mora long (such as, those with long vowels or final consonants). In each case, it was found that the duration of a word stays very close to a target duration that depends on the number of moras in it. This is achieved by stretching or compressing the duration of neighboring segments and adjacent moras. Thus increasing the number of segments in two-mora syllables results in lengthening, not the expected shortening, of other segments in the heavier syllable.     

Some effects of duration on vowel recognition

This study was designed to examine the role of duration in vowel perception by testing listeners on the identification of CVC syllables generated at different durations. Test signals consisted of synthesized versions of 300 utterances selected from a large, multitalker database of /hVd/ syllables [Hillenbrand et al., J. Acoust. Soc. Am. 97, 3099-3111 (1995)]. Four versions of each utterance were synthesized: (1) an original duration set (vowel duration matched to the original utterance), (2) a neutral duration set (duration fixed at 272 ms, the grand mean across all vowels), (3) a short duration set (duration fixed at 144 ms, two standard deviations below the mean), and (4) a long duration set (duration fixed at 400 ms, two standard deviations above the mean). Experiment 1 used a formant synthesizer, while a second experiment was an exact replication using a sinusoidal synthesis method that represented the original vowel spectrum more precisely than the formant synthesizer. Findings included (1) duration had a small overall effect on vowel identity since the great majority of signals were identified correctly at their original durations and at all three altered durations; (2) despite the relatively small average effect of duration, some vowels, especially [see text] and [see text], were significantly affected by duration; (3) some vowel contrasts that differ systematically in duration, such as [see text], and [see text], were minimally affected by duration; (4) a simple pattern recognition model appears to be capable of accounting for several features of the listening test results, especially the greater influence of duration on some vowels than others; and (5) because a formant synthesizer does an imperfect job of representing the fine details of the original vowel spectrum, results using the formant-synthesized signals led to a slight overestimate of the role of duration in vowel recognition, especially for the shortened vowels.     

通用实时语言识别系统——RTSRS(01)

本文描述一个通用实时语言识别系统——RTSRS(01)。在以前工作的基础上,每条口呼命令的参数在时间域上规正,采用二值频谱,大大压缩了参考音的参数存贮量,同时应用新的求差距的办法,使得识别所需的时间大为缩短,以致字表为200时能实时识别。专人的识别结果为:口呼数字,99.7％;20句话(每句7字),99.7％;四字成语100个,99.5％;四字成语150个,99.3％;四字成语200个,98.8％;四字成语400个,99.7％。非正式的实验表明,对于不同音节数的字表,乃至口呼英语数字或BASIC语句名字等,都有高的正确识别率。 关键词：     

Features of stimulation affecting tonal-speech perception: implications for cochlear prostheses

Tone languages differ from English in that the pitch pattern of a single-syllable word conveys lexical meaning. In the present study, dependence of tonal-speech perception on features of the stimulation was examined using an acoustic simulation of a CIS-type speech-processing strategy for cochlear prostheses. Contributions of spectral features of the speech signals were assessed by varying the number of filter bands, while contributions of temporal envelope features were assessed by varying the low-pass cutoff frequency used for extracting the amplitude envelopes. Ten normal-hearing native Mandarin Chinese speakers were tested. When the low-pass cutoff frequency was fixed at 512 Hz, consonant, vowel, and sentence recognition improved as a function of the number of channels and reached plateau at 4 to 6 channels. Subjective judgments of sound quality continued to improve as the number of channels increased to 12, the highest number tested. Tone recognition, i.e., recognition of the four Mandarin tone patterns, depended on both the number of channels and the low-pass cutoff frequency. The trade-off between the temporal and spectral cues for tone recognition indicates that temporal cues can compensate for diminished spectral cues for tone recognition and vice versa. An additional tone recognition experiment using syllables of equal duration showed a marked decrease in performance, indicating that duration cues contribute to tone recognition. A third experiment showed that recognition of processed FM patterns that mimic Mandarin tone patterns was poor when temporal envelope and duration cues were removed.     

Quantitative evaluation of lexical status,word frequency,and neighborhood density as context effects in spoken word recognition

Listeners identified a phonetically balanced set of consonant-vowel-consonant (CVC) words and nonsense syllables in noise at four signal-to-noise ratios. The identification scores for phonemes and syllables were analyzed using the j-factor model [Boothroyd and Nittrouer, J. Acoust. Soc. Am. 84, 101-114 (1988)], which measures the perceptual independence of the parts of a whole. Results indicate that nonsense CVC syllables are perceived as having three independent phonemes, while words show j = 2.34 independent units. Among the words, high-frequency words are perceived as having significantly fewer independent units than low-frequency words. Words with dense phonetic neighborhoods are perceived as having 0.5 more independent units than words with sparse neighborhoods. The neighborhood effect in these data is due almost entirely to density as determined by the initial consonant and vowel, demonstrated in analyses by subjects and items, and correlation analyses of syllable recognition with the neighborhood activation model [Luce and Pisoni, Ear Hear. 19, 1-36 (1998)]. The j factors are interpreted as measuring increased efficiency of the perception of word-final consonants of words in sparse neighborhoods during spoken word recognition.     

Presynaptic action of neurotensin on dopamine release through inhibition of D2 receptor function

Background

Statistical learning is a candidate for one of the basic prerequisites underlying the expeditious acquisition of spoken language. Infants from 8 months of age exhibit this form of learning to segment fluent speech into distinct words. To test the statistical learning skills at birth, we recorded event-related brain responses of sleeping neonates while they were listening to a stream of syllables containing statistical cues to word boundaries.

Results

We found evidence that sleeping neonates are able to automatically extract statistical properties of the speech input and thus detect the word boundaries in a continuous stream of syllables containing no morphological cues. Syllable-specific event-related brain responses found in two separate studies demonstrated that the neonatal brain treated the syllables differently according to their position within pseudowords.

Conclusion

These results demonstrate that neonates can efficiently learn transitional probabilities or frequencies of co-occurrence between different syllables, enabling them to detect word boundaries and in this way isolate single words out of fluent natural speech. The ability to adopt statistical structures from speech may play a fundamental role as one of the earliest prerequisites of language acquisition.     

Phonologically determined asymmetries in vocabulary structure across languages

Studies of spoken-word recognition have revealed that competition from embedded words differs in strength as a function of where in the carrier word the embedded word is found and have further shown embedding patterns to be skewed such that embeddings in initial position in carriers outnumber embeddings in final position. Lexico-statistical analyses show that this skew is highly attenuated in Japanese, a noninflectional language. Comparison of the extent of the asymmetry in the three Germanic languages English, Dutch, and German allows the source to be traced to a combination of suffixal morphology and vowel reduction in unstressed syllables.     

Perception of silent-center syllables by native and non-native English speakers

The amount of acoustic information that native and non-native listeners need for syllable identification was investigated by comparing the performance of monolingual English speakers and native Spanish speakers with either an earlier or a later age of immersion in an English-speaking environment. Duration-preserved silent-center syllables retaining 10, 20, 30, or 40 ms of the consonant-vowel and vowel-consonant transitions were created for the target vowels /i, I, eI, epsilon, ae/ and /a/, spoken by two males in /bVb/ context. Duration-neutral syllables were created by editing the silent portion to equate the duration of all vowels. Listeners identified the syllables in a six-alternative forced-choice task. The earlier learners identified the whole-word and 40 ms duration-preserved syllables as accurately as the monolingual listeners, but identified the silent-center syllables significantly less accurately overall. Only the monolingual listener group identified syllables significantly more accurately in the duration-preserved than in the duration-neutral condition, suggesting that the non-native listeners were unable to recover from the syllable disruption sufficiently to access the duration cues in the silent-center syllables. This effect was most pronounced for the later learners, who also showed the most vowel confusions and the greatest decrease in performance from the whole word to the 40 ms transition condition.     

基于长短时记忆神经网络的能谱核素识别方法

针对新兴的能谱核素识别方法在混合放射性核素的噪声环境中存在识别速度慢、准确率较低等问题,提出了基于长短时记忆神经网络(LSTM)的能谱核素识别方法。实验使用溴化镧(LaBr3)晶体探测器,分别对环境中60Co、137Cs放射性源分组测量得到能谱数据集,首先使用数据平滑方法和归一化方法进行数据预处理,然后将能谱数据按时间序列分组以获得可用的输入序列数组,最后训练LSTM模型得到预测结果。通过基于BP神经网络和卷积神经网络(CNN)的两个能谱识别模型进行对比,得到在测试集中平均识别率分别为83.45%和86.21%,而LSTM能谱识别模型平均识别率为93.04%,实验结果表明,该能谱模型在核素识别效果中表现较好,可用于快速的能谱核素识别设备上。     

A timing model for word-initial CV syllables in Modern Greek

Measurements of the temporal characteristics of word-initial stressed syllables in CV CV-type words in Modern Greek showed that the timing of the initial consonant in terms of its closure duration and voice onset time (VOT) is dependent on place and manner of articulation. This is contrary to recent accounts of word-initial voiceless consonants in English which propose that closure and VOT together comprise a voiceless interval independent of place and manner of articulation. The results also contribute to the development of a timing model for Modern Greek which generates closure, VOT, and vowel durations for word-initial, stressed CV syllables. The model is made up of a series of rules operating in an ordered fashion on a given word duration to derive first a stressed syllable duration and then all intrasyllabic acoustic intervals.     

Word-internal versus word-peripheral consonantal duration patterns in three languages

Segmental duration patterns have long been used to support the proposal that syllables are basic speech planning units, but production experiments almost always confound syllable and word boundaries. The current study tried to remedy this problem by comparing word-internal and word-peripheral consonantal duration patterns. Stress and sequencing were used to vary the nominal location of word-internal boundaries in American English productions of disyllabic nonsense words with medial consonant sequences. The word-internal patterns were compared to those that occurred at the edges of words, where boundary location was held constant and only stress and sequence order were varied. The English patterns were then compared to patterns from Russian and Finnish. All three languages showed similar effects of stress and sequencing on consonantal duration, but an independent effect of syllable position was observed only in English and only at a word boundary. English also showed stronger effects of stress and sequencing across a word boundary than within a word. Finnish showed the opposite pattern, whereas Russian showed little difference between word-internal and word-peripheral patterns. Overall, the results suggest that the suprasegmental units of motor planning are language-specific and that the word may be more a relevant planning unit in English.     

主成分分析结合支持向量机辅助激光诱导击穿光谱对塑料快速分类识别

大量废弃的塑料制品给生态环境造成严重破坏,当务之急是要对塑料进行分类回收。传统的分类方法普遍存在成本高,效率低,操作复杂等问题,不能满足工业生产的需要。激光诱导击穿光谱技术由于具备简单灵活,快速灵敏等优点,在物质鉴别领域有广泛应用。采用激光诱导击穿光谱技术结合主成分分析（PCA）和支持向量机（SVM）算法对20种塑料进行分类识别研究。由于目前有关塑料分类识别速率的研究报道较少,该实验在保证识别准确率的前提下,进一步研究和分析实验过程耗费的时间,满足工业生产中快速分类的要求。每种塑料采集100组光谱数据,随机选取50组数据作为训练集建立模型,余下50组作为测试集测试模型的分类识别效果,所以训练集和测试集各有1 000组光谱数据。将训练集的数据不加处理地输入SVM中进行训练,并采用5折交叉验证建立最佳模型,此时测试集的识别准确率为99.90%,建模时间为1小时58分41.13秒,预测时间为11.96 s。由此可见,单纯使用SVM算法可以得到很高的准确率,但是需要耗费大量时间。为了提高实验效率,引入主成分分析算法,将原来的高维数据变换成低维数据,并用降维后的数据训练模型。针对不同的主成分个数,均采用随机训练十次再取平均值的方法获得相关数值。实验表明,当选取主成分个数为13时,得到相应的识别准确率为99.80%,而PCA处理时间为1.44 s,建模时间为12.16 s,预测时间仅为0.02 s。虽然PCA算法结合SVM算法在对20种塑料进行分类识别时准确率有轻微下降,但是大大减少了模型训练的时间,实验效率得到很大程度的提高。结果表明,结合两种算法辅助激光诱导击穿光谱可以对塑料进行快速准确的分类识别。     

The use of acoustic cues for phonetic identification: effects of spectral degradation and electric hearing

Although some cochlear implant (CI) listeners can show good word recognition accuracy, it is not clear how they perceive and use the various acoustic cues that contribute to phonetic perceptions. In this study, the use of acoustic cues was assessed for normal-hearing (NH) listeners in optimal and spectrally degraded conditions, and also for CI listeners. Two experiments tested the tense/lax vowel contrast (varying in formant structure, vowel-inherent spectral change, and vowel duration) and the word-final fricative voicing contrast (varying in F1 transition, vowel duration, consonant duration, and consonant voicing). Identification results were modeled using mixed-effects logistic regression. These experiments suggested that under spectrally-degraded conditions, NH listeners decrease their use of formant cues and increase their use of durational cues. Compared to NH listeners, CI listeners showed decreased use of spectral cues like formant structure and formant change and consonant voicing, and showed greater use of durational cues (especially for the fricative contrast). The results suggest that although NH and CI listeners may show similar accuracy on basic tests of word, phoneme or feature recognition, they may be using different perceptual strategies in the process.     

Pitch accent in spoken-word recognition in Japanese

Three experiments addressed the question of whether pitch-accent information may be exploited in the process of recognizing spoken words in Tokyo Japanese. In a two-choice classification task, listeners judged from which of two words, differing in accentual structure, isolated syllables had been extracted (e.g., ka from baka HL or gaka LH); most judgments were correct, and listeners' decisions were correlated with the fundamental frequency characteristics of the syllables. In a gating experiment, listeners heard initial fragments of words and guessed what the words were; their guesses overwhelmingly had the same initial accent structure as the gated word even when only the beginning CV of the stimulus (e.g., na- from nagasa HLL or nagashi LHH) was presented. In addition, listeners were more confident in guesses with the same initial accent structure as the stimulus than in guesses with different accent. In a lexical decision experiment, responses to spoken words (e.g., ame HL) were speeded by previous presentation of the same word (e.g., ame HL) but not by previous presentation of a word differing only in accent (e.g., ame LH). Together these findings provide strong evidence that accentual information constrains the activation and selection of candidates for spoken-word recognition.     

Perception and production boundaries between single and geminate stops in Japanese

The theory of relational acoustic invariance [Pickett, E. R., et al. (1999). Phonetica 56, 135-157] was tested with the Japanese stop quantity distinction in disyllables spoken at various rates. The questions were whether the perceptual boundary between the two phonemic categories of single and geminate stops is invariant across rates, and whether there is a close correspondence between the perception and production boundaries. The durational ratio of stop closure to word (where the "word" was defined as disyllables) was previously found to be an invariant parameter that classified the two categories in production, but the present study found that this ratio varied with different speaking rates in perception. However, regression and discriminant analyses of perception and production data showed that treating stop closure as a function of word duration with an intercept term represented the perception and production boundaries very well. This result indicated that the durational ratio of adjusted stop closure (i.e., closure with an added constant) to the word was invariant and distinguished the two phonemic categories clearly. Taken together, the results support the relational acoustic invariance theory, and help refine the theory with regard to exactly what form 'invariance' can take.     

Speaker-independent recognition of Chinese tones

This paper presents a reliable speaker-independent method of recog-nizing Chinese tones.An unbiased center-clipping autocorrelation algorithm ofpitch period extraction is proposed.A two-dimensional decision vector is usedfor recognizing Chinese tones by passing the pitch period sequence through theprocedures of data selection,error correction,data smoothing and curve fitting.The average correct rate of tone recognition for isolated Chinese syllables isover 98%.     

Duration of frication noise required for identification of English fricatives

Natural speech consonant-vowel (CV) syllables [( f, s, theta, s, v, z, ?] followed by [i, u, a]) were computer edited to include 20-70 ms of their frication noise in 10-ms steps as measured from their onset, as well as the entire frication noise. These stimuli, and the entire syllables, were presented to 12 subjects for consonant identification. Results show that the listener does not require the entire fricative-vowel syllable in order to correctly perceive a fricative. The required frication duration depends on the particular fricative, ranging from approximately 30 ms for [s, z] to 50 ms for [f, s, v], while [theta, ?] are identified with reasonable accuracy in only the full frication and syllable conditions. Analysis in terms of the linguistic features of voicing, place, and manner of articulation revealed that fricative identification in terms of place of articulation is much more affected by a decrease in frication duration than identification in terms of voicing and manner of articulation.     

Evaluating the function of phonetic perceptual phenomena within speech recognition: an examination of the perception of /d/-/t/ by adult cochlear implant users

This study examined whether cochlear implant users must perceive differences along phonetic continua in the same way as do normal hearing listeners (i.e., sharp identification functions, poor within-category sensitivity, high between-category sensitivity) in order to recognize speech accurately. Adult postlingually deafened cochlear implant users, who were heterogeneous in terms of their implants and processing strategies, were tested on two phonetic perception tasks using a synthetic /da/-/ta/ continuum (phoneme identification and discrimination) and two speech recognition tasks using natural recordings from ten talkers (open-set word recognition and forced-choice /d/-/t/ recognition). Cochlear implant users tended to have identification boundaries and sensitivity peaks at voice onset times (VOT) that were longer than found for normal-hearing individuals. Sensitivity peak locations were significantly correlated with individual differences in cochlear implant performance; individuals who had a /d/-/t/ sensitivity peak near normal-hearing peak locations were most accurate at recognizing natural recordings of words and syllables. However, speech recognition was not strongly related to identification boundary locations or to overall levels of discrimination performance. The results suggest that perceptual sensitivity affects speech recognition accuracy, but that many cochlear implant users are able to accurately recognize speech without having typical normal-hearing patterns of phonetic perception.     

早晚期混响划分对理想比值掩蔽在语音识别性能上的影响

真实环境中存在的噪声和混响会降低语音识别系统的性能。封闭空间中的混响包括直达声、早期反射和后期混响3部分,它们对语音识别系统具有不同的影响.我们研究了早期反射和后期混响的不同划分方法,以其中的早期反射为目标语音,计算出了不同的理想比值掩蔽并研究了它们对语音识别系统性能的影响;在此基础上,利用双向长短时记忆网络(BLSTM)估计理想比值掩蔽,测试它们对语音识别系统性能的影响.实验结果表明,基于Abel早期反射和后期混响的划分方法,理想比值掩蔽能够降低词错误率约2.8%;基于BLSTM的估计方法过低估计了理想比值掩蔽,未能有效提高语音识别系统的性能。