Perceiving unstressed vowels in foreign-accented English

This paper investigated how foreign-accented stress cues affect on-line speech comprehension in British speakers of English. While unstressed English vowels are usually reduced to /?/, Dutch speakers of English only slightly centralize them. Speakers of both languages differentiate stress by suprasegmentals (duration and intensity). In a cross-modal priming experiment, English listeners heard sentences ending in monosyllabic prime fragments--produced by either an English or a Dutch speaker of English--and performed lexical decisions on visual targets. Primes were either stress-matching ("ab" excised from absurd), stress-mismatching ("ab" from absence), or unrelated ("pro" from profound) with respect to the target (e.g., ABSURD). Results showed a priming effect for stress-matching primes only when produced by the English speaker, suggesting that vowel quality is a more important cue to word stress than suprasegmental information. Furthermore, for visual targets with word-initial secondary stress that do not require vowel reduction (e.g., CAMPAIGN), resembling the Dutch way of realizing stress, there was a priming effect for both speakers. Hence, our data suggest that Dutch-accented English is not harder to understand in general, but it is in instances where the language-specific implementation of lexical stress differs across languages.     

Adapting to suprasegmental lexical stress errors in foreign-accented speech

Can native listeners rapidly adapt to suprasegmental mispronunciations in foreign-accented speech? To address this question, an exposure-test paradigm was used to test whether Dutch listeners can improve their understanding of non-canonical lexical stress in Hungarian-accented Dutch. During exposure, one group of listeners heard a Dutch story with only initially stressed words, whereas another group also heard 28 words with canonical second-syllable stress (e.g., EEKhorn, "squirrel" was replaced by koNIJN "rabbit"; capitals indicate stress). The 28 words, however, were non-canonically marked by the Hungarian speaker with high pitch and amplitude on the initial syllable, both of which are stress cues in Dutch. After exposure, listeners' eye movements were tracked to Dutch target-competitor pairs with segmental overlap but different stress patterns, while they listened to new words from the same Hungarian speaker (e.g., HERsens, herSTEL, "brain," "recovery"). Listeners who had previously heard non-canonically produced words distinguished target-competitor pairs better than listeners who had only been exposed to Hungarian accent with canonical forms of lexical stress. Even a short exposure thus allows listeners to tune into speaker-specific realizations of words' suprasegmental make-up, and use this information for word recognition.     

Short-term adaptation to accented English by younger and older adults

This study examined the effects of age and hearing loss on short-term adaptation to accented speech. Data from younger and older listeners in a prior investigation [Gordon-Salant et al. (2010). J. Acoust. Soc. Am. 128, 444-455] were re-analyzed to examine changes in recognition over four administrations of equivalent lists of English stimuli recorded by native speakers of Spanish and English. Results showed improvement in recognition scores over four list administrations for the accented stimuli but not for the native English stimuli. Group effects emerged but were not involved in any interactions, suggesting that short-term adaptation to accented speech is preserved with aging and with hearing loss.     

基于回归分析的语音识别快速自适应算法

从回归分析的角度推导出最大似然线性回归算法的等价算法——最小二乘线性回归算法,以及相应的多元线性回归模型。该模型中回归因子间存在着多重共线性,它导致了算法在自适应数据很少时失效。为减轻多重共线性的影响,提出改进算法:伪自适应数据算法。实验表明,当仅有1s~3s自适应数据时,新算法使得系统误识率相对下降2%~6%,随着自适应数据增多,其性能与最大似然线性回归(或最小二乘线性同归)算法趋于一致。     

Rapid head-related transfer function adaptation using a virtual auditory environment

The paper reports on the ability of people to rapidly adapt in localizing virtual sound sources in both azimuth and elevation when listening to sounds synthesized using non-individualized head-related transfer functions (HRTFs). Participants were placed within an audio-kinesthetic Virtual Auditory Environment (VAE) platform that allows association of the physical position of a virtual sound source with an alternate set of acoustic spectral cues through the use of a tracked physical ball manipulated by the subject. This set-up offers a natural perception-action coupling, which is not limited to the visual field of view. The experiment consisted of three sessions: an initial localization test to evaluate participants' performance, an adaptation session, and a subsequent localization test. A reference control group was included using individual measured HRTFs. Results show significant improvement in localization performance. Relative to the control group, participants using non-individual HRTFs reduced localization errors in elevation by 10° with three sessions of 12 min. No significant improvement was found for azimuthal errors or for single session adaptation.     

Articulatory and acoustic adaptation to palatal perturbation

Previous work has established that speakers have difficulty making rapid compensatory adjustments in consonant production (especially in fricatives) for structural perturbations of the vocal tract induced by artificial palates with thicker-than-normal alveolar regions. The present study used electromagnetic articulography and simultaneous acoustic recordings to estimate tongue configurations during production of [s s? t k] in the presence of a thin and a thick palate, before and after a practice period. Ten native speakers of English participated in the study. In keeping with previous acoustic studies, fricatives were more affected by the palate than were the stops. The thick palate lowered the center of gravity and the jaw was lower and the tongue moved further backwards and downwards. Center of gravity measures revealed complete adaptation after training, and with practice, subjects' decreased interlabial distance. The fact that adaptation effects were found for [k], which are produced with an articulatory gesture not directly impeded by the palatal perturbation, suggests a more global sensorimotor recalibration that extends beyond the specific articulatory target.     

Sensorimotor adaptation to feedback perturbations of vowel acoustics and its relation to perception

The role of auditory feedback in speech motor control was explored in three related experiments. Experiment 1 investigated auditory sensorimotor adaptation: the process by which speakers alter their speech production to compensate for perturbations of auditory feedback. When the first formant frequency (F1) was shifted in the feedback heard by subjects as they produced vowels in consonant-vowel-consonant (CVC) words, the subjects' vowels demonstrated compensatory formant shifts that were maintained when auditory feedback was subsequently masked by noise-evidence of adaptation. Experiment 2 investigated auditory discrimination of synthetic vowel stimuli differing in F1 frequency, using the same subjects. Those with more acute F1 discrimination had compensated more to F1 perturbation. Experiment 3 consisted of simulations with the directions into velocities of articulators model of speech motor planning, which showed that the model can account for key aspects of compensation. In the model, movement goals for vowels are regions in auditory space; perturbation of auditory feedback invokes auditory feedback control mechanisms that correct for the perturbation, which in turn causes updating of feedforward commands to incorporate these corrections. The relation between speaker acuity and amount of compensation to auditory perturbation is mediated by the size of speakers' auditory goal regions, with more acute speakers having smaller goal regions.     

Rapid Method to Screen Unopened Bottles to Detect Concealed Drugs

A bottle screening method to detect smuggling drugs was developed based on a series of rapid and automated magnetic resonance measurements. Liquid alteration is detected by evaluating chemical and physical properties of the liquid, scanning the bottle with a compact, non-contact magnetic resonance probe. Chemical and molecular diffusion changes are detected by means of the magnetic resonance relaxation time. The inspection device automatically detects the presence of concealed powders dissolved in liquids in a second timescale. The non-ionizing, non-contact method effectively screens bottles, regardless of their shape, size, and color. The proposed system configuration does not require a large magnet generating uniform magnetic fields; rather it inspects the liquid using a compact probe positioned on the wall of the bottle. For a variety of samples tested, the screening does not require detailed information on the expected content of the bottle.     

First experience and adaptation of existing tools to ATLAS distributed analysis

The ATLAS production system has been successfully used to run production of simulation data at an unprecedented scale in ATLAS. Up to 10000 jobs were processed on about 100 sites in one day. The experiences obtained operating the system on several grid flavours was essential to perform a user analysis using grid resources. First tests of the distributed analysis system were then performed. In the preparation phase data was registered in the LHC file catalog (LFC) and replicated in external sites. For the main test, few resources were used. All these tests are only a first step towards the validation of the computing model. The ATLAS management computing board decided to integrate the collaboration efforts in distributed analysis in only one project, GANGA. The goal is to test the reconstruction and analysis software in a large scale Data production using grid flavors in several sites. GANGA allows trivial switching between running test jobs on a local batch system and running large-scale analyses on the grid; it provides job splitting and merging, and includes automated job monitoring and output retrieval.     

Effects of stimulus variability and adult aging on adaptation to time-compressed speech

With as few as 10-20 sentences of exposure, listeners are able to adapt to speech that is highly distorted compared to that which is encountered in everyday conversation. The current study examines the extent to which adaptation to time-compressed speech can be impeded by disrupting the continuity of the exposure sentences, and whether this differs between young and older adult listeners when they are equated for starting accuracy. In separate sessions conducted one week apart, the degree of adaptation was assessed in four exposure conditions, all of which involved exposure to the same number of time-compressed sentences. A continuous exposure condition involved presentation of the time-compressed sentences without interruption. Two alternation conditions alternated time-compressed speech and uncompressed speech by single sentences or groups of four sentences. A fourth condition presented sentences that were separated by a period of silence but no uncompressed speech. For all conditions, neither young nor older adults' overall level of learning was influenced by disruptions to the exposure sentences. In addition, participants' performance showed reliable improvement across the first and subsequent sessions. These results support robust learning mechanisms in speech perception that remain functional throughout the lifespan.     

Time course of adaptation and recovery from adaptation in the cat auditory-nerve neurophonic

The auditory-nerve neurophonic (ANN) reflects the ensemble response of phase-locked firing in single auditory-nerve fibers to sustained signals. Consequently, neural response properties such as adaptation and recovery from adaptation can be observed. In this study, ANN responses to 800-Hz, 100-ms tones presented at 10-30-dB SL were recorded using bipolar platinum-iridium electrodes placed on the auditory nerve of the cat. The cat ANN adaptation properties were determined and fit to the equation: A(tp) = Yre(-tp/tau Ar) + Yse(-tp/tau As) + Ass. The rapid time constant of adaptation (tau Ar) was invariant across stimulus level, with a mean value of 4.8 (+/- 2.1) ms. The short-term time constant (tau As) decreased approximately 21 ms for each 10-dB increase in probe amplitude. The mean tau As was 116 ms at 10 dB SL, 83.2 ms at 20 dB SL, and 73.5 ms at 30 dB SL. The ANN recovery from adaptation data was analyzed and fit to the equation: A(delta t) = Amax - Yre(-delta t/tau Rr) - Yse(-delta t/tau Rs). Here, tau Rr, the rapid time constant of recovery, and tau Rs, the short-term time constant, were independent of masker intensity in the studied range, with values of 16.2(+/- 9.8) and 125(+/- 50.1) ms, respectively. The results of this study indicate that ANN time constants are comparable to those measured for single units and that the adaptation behavior of phase-locked and nonphase-locked activity appears to be similar.     

Application of Rapid Scanning Spectrometry to Atomic Spectroanalytical Analysis

Abstract

Determinations of metal content by single element atomic spectroscopy are well-established procedures in analytical laboratories. However, there has been considerable interest in methods for simultaneous multielement determinations as indicated by a recent review [1]. Correspondingly, much effort has been devoted to the development of detectors for multielement systems [2–8]. This review will report the application of rapid scanning spectrometers (RSS) to atomic spectroanalytical analysis. An instrument of this type can scan a selected wavelength window or region on a time scale ranging from a few microseconds to several seconds [4]. The scope of this review will be limited to RSS employing a mechanical means of rapid scanning, although much attention has been directed toward imaging devices such as the Vidicon tube and photodiode arrays [6–8]. The optical characteristics of the spectrometers, as well as the analytical results, will be discussed.     

匹配追踪说话人自适应方法

针对现有子空间自适应方法无法确定最佳说话人子空间的问题,提出一种基于匹配追踪的说话人自适应方法。将说话人自适应视为一种高维信号的稀疏分解问题,利用本征音和参考说话人超矢量的各自优势联合构造说话人字典;依据匹配追踪原理,通过迭代优化,以后验方式确定最佳说话人子空间维数及其基矢量。引入冗余基矢量检测与去除机制以保证算法的稳定性,并通过快速递推算法得到新说话人坐标。基于汉语连续语音识别的有监督说话人自适应实验结果表明,与本征音及参考说话人加权方法相比,平均有调音节正识率相对提高了1.9%。     

Electropalatographic, acoustic, and perceptual data on adaptation to a palatal perturbation

Exploring the compensatory responses of the speech production system to perturbation has provided valuable insights into speech motor control. The present experiment was conducted to examine compensation for one such perturbation-a palatal perturbation in the production of the fricative /s/. Subjects wore a specially designed electropalatographic (EPG) appliance with a buildup of acrylic over the alveolar ridge as well as a normal EPG palate. In this way, compensatory tongue positioning could be assessed during a period of target specific and intense practice and compared to nonperturbed conditions. Electropalatographic, acoustic, and perceptual analyses of productions of /asa/ elicited from nine speakers over the course of a one-hour practice period were conducted. Acoustic and perceptual results confirmed earlier findings, which showed improvement in production with a thick artificial palate in place over the practice period; the EPG data showed overall increased maximum contact as well as increased medial and posterior contact for speakers with the thick palate in place, but little change over time. Negative aftereffects were observed in the productions with the thin palate, indicating recalibration of sensorimotor processes in the face of the oral-articulatory perturbation. Findings are discussed with regard to the nature of adaptive articulatory skills.