Age-related changes in sensitivity to native phonotactics in Japanese infants

Japanese infants at the ages of 6, 12, and 18 months were tested on their ability to discriminate three nonsense words with different phonotactic status: canonical keetsu, noncanonical but possible keets, and noncanonical and impossible keet. The results showed that 12 and 18 months olds discriminate the keets/keetsu pair, but infants in all age groups fail to discriminate the keets/keet pair. Taken together with the findings in our previous study [Kajikawa et al., J. Acoust. Soc. Am. 120(4), 2278-2284 (2006)], these results suggest that Japanese infants develop the perceptual sensitivity for native phonotactics after 6 months of age, and that this sensitivity is limited to canonical patterns at this early developmental stage.     

Pure-tone sensitivity of human infants

Pure-tone thresholds at frequencies ranging from 250 to 8000 Hz were estimated for 3-, 6-, and 12-month-old infants and for adults, using the Observer-based Psychoacoustic Procedure (OPP). Sounds were presented monaurally using an earphone. Psychometric functions of infants were similar to those of adults, although 3-month-olds had shallower functions at higher frequencies. The thresholds of 6- and 12-month-old infants were 10-15 dB higher than those of the adults, with the difference being greater at lower frequencies. This result is in general agreement with results from other laboratories. The thresholds of 3-month-olds were 15-30 dB higher than those of adults. The greatest difference between 3-month-olds and adults was at 8000 Hz. This threshold difference is smaller than that reported in earlier behavioral studies; higher thresholds at high frequencies have been previously reported for newborn and 3-month-old infants. The relative contributions of sensory and nonsensory variables to these age differences are discussed.     

音子配列学语种识别系统中特征选择方法的研究

将信息增益和加权log似然比特征选择方法应用于音子配列学语种识别系统中进行特征降维。在美国国家标准技术研究院2009年语种识别评测数据集上进行实验,分别使用信息增益和加权log似然比准则以及传统的互信息,χ²统计量方法对数量巨大的N-gram进行特征选择,从中选出最具有鉴别性的部分组成特征向量,并用分类器进行分类。结果显示,当根据信息增益和加权log似然比准则选取一定数量的特征时,系统性能与使用全部特征的基线系统相比略好;当选取的特征数量很少时,信息增益和加权log似然比方法的性能要优于传统的互信息和χ²统计量方法。实验表明,在音子配列学语种识别系统中,信息增益和加权log似然比方法均可以有效地去除冗余信息,降低特征向量的维数,并且能使系统性能得到一定的提高。     

Frequency and form as determinants of functor sensitivity in English-acquiring infants

High-frequency functors are arguably among the earliest perceived word forms and may assist extraction of initial vocabulary items. Canadian 11- and 8-month-olds were familiarized to pseudo-nouns following either a high-frequency functor the or a low-frequency functor her versus phonetically similar mispronunciations of each, kuh and ler, and then tested for recognition of the pseudo-nouns. A preceding the (but not kuh, her, ler) facilitated extraction of the pseudo-nouns for 11-month-olds; the is thus well-specified in form for these infants. However, both the and kuh (but not her-ler) facilitated segmentation for 8-month-olds, suggesting an initial underspecified representation of high-frequency functors.     

Cross-language differences in fundamental frequency range: a comparison of English and German

This paper presents a systematic comparison of various measures of f0 range in female speakers of English and German. F0 range was analyzed along two dimensions, level (i.e., overall f0 height) and span (extent of f0 modulation within a given speech sample). These were examined using two types of measures, one based on "long-term distributional" (LTD) methods, and the other based on specific landmarks in speech that are linguistic in nature ("linguistic" measures). The various methods were used to identify whether and on what basis or bases speakers of these two languages differ in f0 range. Findings yielded significant cross-language differences in both dimensions of f0 range, but effect sizes were found to be larger for span than for level, and for linguistic than for LTD measures. The linguistic measures also uncovered some differences between the two languages in how f0 range varies through an intonation contour. This helps shed light on the relation between intonational structure and f0 range.     

蝉类用于声通讯的鸣声特性及其飞行趋声范围的估计

本文比较了不同种类的蝉鸣声和听觉特性。结果表明,蝉类用于飞行趋声的鸣声种特性不仅与鸣声的优势频率有关,而且与鸣声的音调和节奏的变化有关。同时,鸣声的优势频率与相应的生态环境有关,其飞行趋声范围一般不超过200m,主要范围约100-60左右。     

Experimental intensity patterns obtained from a 2D shearing interferometer with adaptable sensitivity

The interferometric intensity patterns from a 2D shearing interferometer are shown and discussed. The intensity patterns can be obtained in two different approaches incorporating differential and extended wavefront controlled displacements. The reliable directional sensitivity of this interferometer allows the optimization of the measurement parameters to estimate the wavefront of the intensity patterns by regularization techniques.     

Manipulating the "straightness" and "curvature" of patterns of interaural cross correlation affects listeners' sensitivity to changes in interaural delay

The purpose of this study was to test the hypothesis that stimuli characterized by "straight" trajectories of their patterns of cross correlation foster greater sensitivity to changes in interaural temporal disparities (ITDs) than do stimuli characterized by more "curved" trajectories of their patterns of cross correlation. To do so, sensitivity to changes in ITD was measured, as a function of duration, using a set of "reference" stimuli that yielded differing relative amounts of straightness within their patterns of cross correlation while keeping the dominant trajectory at or near midline. The relative amounts of straightness were manipulated by employing specific combinations of bandwidth, ITD, and interaural phase disparity (IPD) of Gaussian noises centered at 500 Hz. The results were consistent with expectations in that the patterning of the threshold ITDs revealed increasingly poorer sensitivity as greater and greater curvature was imposed on the dominant, "midline," trajectory. The variations in threshold ITD across the stimulus conditions can be accounted for quite well quantitatively by assuming either that the listeners based their judgments on changes in the position of the most central peak of the cross-correlation function or that they based their judgments on changes in the centroid of a second-level cross-correlation function. In a second experiment, binaural detection was measured using a subset of the reference stimuli as maskers. As expected, sensitivity was poorest with the maskers characterized by the greatest curvature, which were also those having the lowest interaural correlation.     

Listener sensitivity to individual talker differences in voice-onset-time

Recent findings in the domains of word and talker recognition reveal that listeners use previous experience with an individual talker's voice to facilitate subsequent perceptual processing of that talker's speech. These findings raise the possibility that listeners are sensitive to talker-specific acoustic-phonetic properties. The present study tested this possibility directly by examining listeners' sensitivity to talker differences in the voice-onset-time (VOT) associated with a word-initial voiceless stop consonant. Listeners were trained on the speech of two talkers. Speech synthesis was used to manipulate the VOTs of these talkers so that one had short VOTs and the other had long VOTs (counterbalanced across listeners). The results of two experiments using a paired-comparison task revealed that, when presented with a short- versus long-VOT variant of a given talker's speech, listeners could select the variant consistent with their experience of that talker's speech during training. This was true when listeners were tested on the same word heard during training and when they were tested on a different word spoken by the same talker, indicating that listeners generalized talker-specific VOT information to a novel word. Such sensitivity to talker-specific acoustic-phonetic properties may subserve at least in part listeners' capacity to benefit from talker-specific experience.     

Noise sensitivity to gamma radiation in Si-jfet devices

The result of noise measurements for a Charge Sensitive Preamplifier based on Si-Field Effect Transistor exposed to a total Gamma ray dose of 30 v Mrad have been reported. The radiation effect on the DC parameters of single transistors was also tested. Our study has shown that, there are no changes on the DC parameters. Meanwhile the noise level, which was evaluated by the total equivalent noise charge, was clearly increased. The results of noise measurements were analyzed and compared with theoretical predictions. The temperature and time-dependent effects on the noise had also been reported after irradiation. All measurements were performed for biased and unbiased irradiated transistors.     

Individual differences in the sensitivity to pitch direction

It is commonly assumed that one can always assign a direction-upward or downward-to a percept of pitch change. The present study shows that this is true for some, but not all, listeners. Frequency difference limens (FDLs, in cents) for pure tones roved in frequency were measured in two conditions. In one condition, the task was to detect frequency changes; in the other condition, the task was to identify the direction of frequency changes. For three listeners, the identification FDL was about 1.5 times smaller than the detection FDL, as predicted (counterintuitively) by signal detection theory under the assumption that performance in the two conditions was limited by one and the same internal noise. For three other listeners, however, the identification FDL was much larger than the detection FDL. The latter listeners had relatively high detection FDLs. They had no difficulty in identifying the direction of just-detectable changes in intensity, or in the frequency of amplitude modulation. Their difficulty in perceiving the direction of small frequency/pitch changes showed up not only when the task required absolute judgments of direction, but also when the directions of two successive frequency changes had to be judged as identical or different.     

Enhance sensitivity to illumination and synchronization in light-dependent neurons

When a phototube is activated to connect a neural circuit, the output voltage becomes sensitive to external illumination because the photocurrent across the phototube can be controlled by external electromagnetic wave. The channel currents from different branch circuits have different impacts on the outputs voltage of the neural circuit. In this paper, a phototube is incorporated into different branch circuits in a simple neural circuit, and then a light-controlled neuron is obtained for further nonlinear analysis. Indeed, the phototube is considered as exciting source when it is activated by external illumination, and two kinds of light-sensitive neurons are obtained when the phototube is connected to capacitor or induction coil, respectively. Electric synapse coupling is applied to detect possible synchronization between two functional neurons, and the energy consumption along the coupling channel via resistor is estimated. The analog circuits for the two kinds of light-sensitive neurons are supplied for further confirmation by using Multisim. It is found that two light-sensitive neurons and neural circuits can be synchronized by taming the coupling intensity carefully. It provides possible clues to understand the synchronization mechanism for eyes and artificial sensors which are sensitive to illumination. Finally, a section for open problems is supplied for further investigation about its collective behaviors in the network with/without synapse coupling.     

Dynamic transition from modelike patterns to turbulentlike patterns in a broad-area Nd:YAG laser

We report the first experimental observation to our knowledge of a dynamic transition from modelike patterns to completely disordered patterns in a large-aspect-ratio Nd:YAG laser. Recordings of near-field patterns with an integration time as small as 1 ns allow us to follow the evolution of the transverse intensity profile along the output pulse of the laser.     

The sensitivity of photoemulsions and its relation to the sensitivity of a photocathode

The sensitivity limitations arising from fluctuations in photoemulsions are discussed and the conditions under which the limitations reach a minimum are described. The photoemulsion area which corresponds to a minimum number of quanta at a certain registration accuracy is derived. Estimates are given which indicate how the required light sum increases when the area exceeds the optimum value. The sensitivities of photoemulsions and photocathodes are compared. It could be shown that the photoemulsion sensitivity deteriorates to a certain extent when the exposure range increases. A selection of the exposure working region is suggested which, in contrast to the linear portion of the characteristic curve, permits measuments with a smaller light input and in a wider exposure range.     

Neural responses to auditory temporal patterns

Sets of regularly repeating auditory stimuli elicit unique perceptions; listeners are able to identify specific temporal patterns. Some temporal patterns are unambiguous (only one pattern can be perceived), while others are ambiguous (numerous patterns can be detected). While the psychophysical properties of such percepts have been well studied, little is known about the underlying neurological bases of temporal pattern perception. In this experiment, the role of adaptation in temporal pattern perception is examined by studying neural responses in four cats to a temporal pattern that is perceptually unambiguous and one that is perceptually ambiguous. Measurements were made of the whole-nerve action potential, the auditory brainstem response, and potentials from the surface of the primary auditory cortex. The adaptation patterns corresponded with the perceptual organization of temporal patterns in humans at all levels of the nervous system studied.     

Cortical sensitivity to periodicity of speech sounds

Previous non-invasive brain research has reported auditory cortical sensitivity to periodicity as reflected by larger and more anterior responses to periodic than to aperiodic vowels. The current study investigated whether there is a lower fundamental frequency (F0) limit for this effect. Auditory evoked fields (AEFs) elicited by natural-sounding 400 ms periodic and aperiodic vowel stimuli were measured with magnetoencephalography. Vowel F0 ranged from normal male speech (113 Hz) to exceptionally low values (9 Hz). Both the auditory N1m and sustained fields were larger in amplitude for periodic than for aperiodic vowels. The AEF sources for periodic vowels were also anterior to those for the aperiodic vowels. Importantly, the AEF amplitudes and locations were unaffected by the F0 decrement of the periodic vowels. However, the N1m latency increased monotonically as F0 was decreased down to 19 Hz, below which this trend broke down. Also, a cascade of transient N1m-like responses was observed in the lowest F0 condition. Thus, the auditory system seems capable of extracting the periodicity even from very low F0 vowels. The behavior of the N1m latency and the emergence of a response cascade at very low F0 values may reflect the lower limit of pitch perception.     

Pressure sensitivity kernels applied to time-reversal acoustics

Sensitivity kernels for receptions of broadband sound transmissions are used to study the effect of the transmitted signal on the sensitivity of the reception to environmental perturbations. A first-order Born approximation is used to obtain the pressure sensitivity of the received signal to small changes in medium sound speed. The pressure perturbation to the received signal caused by medium sound speed changes is expressed as a linear combination of single-frequency sensitivity kernels weighted by the signal in the frequency domain. This formulation can be used to predict the response of a source transmission to sound speed perturbations. The stability of time-reversal is studied and compared to that of a one-way transmission using sensitivity kernels. In the absence of multipath, a reduction in pressure sensitivity using time reversal is only obtained with multiple sources. This can be attributed both to the presence of independent paths and to cancellations that occur due to the overlap of sensitivity kernels for different source-receiver paths. The sensitivity kernel is then optimized to give a new source transmission scheme that takes into account knowledge of the medium statistics and is related to the regularized inverse filter.