Individual differences in source identification from synthesized impact sounds

Impact sounds were synthesized according to standard textbook equations given for the motion of freely vibrating membranes, bars, and plates. In a two-interval, forced-choice procedure, highly practiced listeners identified from these sounds predefined target sources based on their material and size, the hardness of the striking mallet, and the presence or absence of light damping applied to the center of the source. Listener decision strategy in each case was determined from a discriminant analysis of trial-by-trial responses resulting in a vector of regression weights given to different acoustic parameters. The analysis revealed significant differences in decision strategy across listeners within identification task, but similarity in decision strategy within listeners across variations in task. Only when the acoustic information for identification was highly constrained (identification of damping) did listeners adopt similar decision strategies approaching that of an ideal observer. Despite the large individual differences in decision strategy, identification accuracy was, in most cases, similar across listeners. Where there were differences in identification accuracy the differences appeared largely related to differences in internal noise and not decision strategy. The results are generally comparable to those obtained for the discrimination of arbitrary tone patterns.     

Correlation characteristics and travel time differences for hydroacoustic signals under directional reception at different depths

Experimental data are presented for the cross-correlation coefficients and travel time differences of audible signals measured at distances of ～60 and ～120 km in an oceanic waveguide. The signals are received simultaneously by two highly directional vertical arrays (with a main lobe width of ～2°) whose centers are at depths of 200 and 450 m. The radiation depths of the pseudonoise signals were 200 and 400 m. The high correlation coefficients (0.75–0.94) obtained for the signals received at different depths suggest that the changes in the frequency spectra of signals arriving over different paths are almost identical. The small fluctuations of the travel time differences (≤0.43 ms for the “water” signals and ≤0.63 ms for the signals reflected from the sea surface) testify to their high stability.     

Analysis of remote detection travel time curves measured from microfluidic channels

Remote detection technique can increase sensitivity of an NMR experiment by several orders of magnitude in microfluidic applications. Travel time experiment is a basic remote detection NMR experiment, which reveals the travel time distribution of the molecules flowing from the encoding coil region to the detector. In this article, we focus on analyzing how flow type (Poiseuille or plug flow), diffusion, dispersion and geometry of the flow channels are manifested in the travel time curves measured from microfluidic channels. We demonstrate that remote detection travel time experiment could be used even as an alternative NMR method for measuring self-diffusion coefficient of a fluid without magnetic field gradients. In addition, we introduce a modified travel time pulse sequence, which removes the signal of unencoded fluid spins as well as the background signal arising from the material inside or close to the detector.     

Uncertainty estimation in seismo-acoustic reflection travel time inversion

This paper develops a nonlinear Bayesian inversion for high-resolution seabed reflection travel time data including rigorous uncertainty estimation and examination of statistical assumptions. Travel time data are picked on seismo-acoustic traces and inverted for a layered sediment sound-velocity model. Particular attention is paid to picking errors which are often biased, correlated, and nonstationary. Non-Toeplitz data covariance matrices are estimated and included in the inversion along with unknown travel time offset (bias) parameters to account for these errors. Simulated experiments show that neglecting error covariances and biases can cause misleading inversion results with unrealistically high confidence. The inversion samples the posterior probability density and provides a solution in terms of one- and two-dimensional marginal probability densities, correlations, and credibility intervals. Statistical assumptions are examined through the data residuals with rigorous statistical tests. The method is applied to shallow-water data collected on the Malta Plateau during the SCARAB98 experiment.     

Categorization and discrimination of nonspeech sounds: differences between steady-state and rapidly-changing acoustic cues

Different patterns of performance across vowels and consonants in tests of categorization and discrimination indicate that vowels tend to be perceived more continuously, or less categorically, than consonants. The present experiments examined whether analogous differences in perception would arise in nonspeech sounds that share critical transient acoustic cues of consonants and steady-state spectral cues of simplified synthetic vowels. Listeners were trained to categorize novel nonspeech sounds varying along a continuum defined by a steady-state cue, a rapidly-changing cue, or both cues. Listeners' categorization of stimuli varying on the rapidly changing cue showed a sharp category boundary and posttraining discrimination was well predicted from the assumption of categorical perception. Listeners more accurately discriminated but less accurately categorized steady-state nonspeech stimuli. When listeners categorized stimuli defined by both rapidly-changing and steady-state cues, discrimination performance was accurate and the categorization function exhibited a sharp boundary. These data are similar to those found in experiments with dynamic vowels, which are defined by both steady-state and rapidly-changing acoustic cues. A general account for the speech and nonspeech patterns is proposed based on the supposition that the perceptual trace of rapidly-changing sounds decays faster than the trace of steady-state sounds.     

Dispersion imaging spectrometer for detecting and locating energetic targets in real time

A conceptual dispersion imaging spectrometer(DIS) is proposed.It consists of a telescope,four prisms,an imaging lens,and a detector.The first prism allows only the first set of wavelengths along the first direction to pass and disperse.The second prism allows only the second set of wavelengths along the second direction,which is perpendicular to the first.The third and fourth prisms are used to compensate for the angular deviations from the optical axes of the first and second prisms,respectively.The proposed DIS disperses the spectra of a target to form an L-shaped dispersion pattern(LDP).The theoretical calculation and numerical simulation of the LDP are presented.The DIS can locate multiple targets based only on data obtained from a single frame.It is suitable for detecting and locating energetic targets in real time.     

Individual differences in the processing of speech and nonspeech sounds by normal-hearing listeners.

While a large portion of the variance among listeners in speech recognition is associated with the audibility of components of the speech waveform, it is not possible to predict individual differences in the accuracy of speech processing strictly from the audiogram. This has suggested that some of the variance may be associated with individual differences in spectral or temporal resolving power, or acuity. Psychoacoustic measures of spectral-temporal acuity with nonspeech stimuli have been shown, however, to correlate only weakly (or not at all) with speech processing. In a replication and extension of an earlier study [Watson et al., J. Acoust. Soc. Am. Suppl. 1 71. S73 (1982)] 93 normal-hearing college students were tested on speech perception tasks (nonsense syllables, words, and sentences in a noise background) and on six spectral-temporal discrimination tasks using simple and complex nonspeech sounds. Factor analysis showed that the abilities that explain performance on the nonspeech tasks are quite distinct from those that account for performance on the speech tasks. Performance was significantly correlated among speech tasks and among nonspeech tasks. Either, (a) auditory spectral-temporal acuity for nonspeech sounds is orthogonal to speech processing abilities, or (b) the appropriate tasks or types of nonspeech stimuli that challenge the abilities required for speech recognition have yet to be identified.     

The effect of interaural differences in envelope shape on the perceived location of sounds (L)

Users of bilateral cochlear implants and a cochlear implant combined with a contralateral hearing aid are sensitive to interaural time differences (ITDs). The way cochlear implant speech processors work and differences between modalities may result in interaural differences in shape of the temporal envelope presented to the binaural system. The effect of interaural differences in envelope shape on ITD sensitivity was investigated with normal-hearing listeners using a 4?kHz pure tone modulated with a periodic envelope with a trapezoid shape in each cycle. In one ear the onset segment of the trapezoid was transformed by a power function. No effect on the just noticeable difference in ITD was found with an interaural difference in envelope shape, but the ITD for a centered percept was significantly different across envelope shape conditions.     

Discrimination of interaural differences of time in the envelopes of high-frequency signals: integration times

Listeners detected interaural differences of time in trains of high-frequency clicks. The manipulated variables were the number of clicks in the train and the period between clicks. Thresholds were compared to an optimal integrator, where the binaural information accrued from each click in the stimulus train is equivalent. In agreement with data reported in the past, integration is optimal only when the period between clicks exceeds approximately 10 ms and when the duration of the entire stimulus train is less than about 250 ms. The first constraint represents a limitation due to a form of "binaural adaptation" and the second is due to a limited "integration period."     

Entropic Dynamics: Quantum Mechanics from Entropy and Information Geometry

Entropic Dynamics (ED) is a framework in which Quantum Mechanics (QM) is derived as an application of entropic methods of inference. The magnitude of the wave function is manifestly epistemic: its square is a probability distribution. The epistemic nature of the phase of the wave function is also clear: it controls the flow of probability. The dynamics is driven by entropy subject to constraints that capture the relevant physical information. The central concern is to identify those constraints and how they are updated. After reviewing previous work I describe how considerations from information geometry allow us to derive a phase space geometry that combines Riemannian, symplectic, and complex structures. The ED that preserves these structures is QM. The full equivalence between ED and QM is achieved by taking account of how gauge symmetry and charge quantization are intimately related to quantum phases and the single‐valuedness of wave functions.     

Geometry from the spectral point of view

In this Letter, we develop geometry from a spectral point of view, the geometric data being encoded by a triple (A. H. D.) of an algebraA represented in a Hilbert spaceH with selfadjoint operatorD. This point of view is dictated by the general framework of noncommutative geometry and allows us to use geometric ideas in many situations beyond Riemannian geometry.

This paper is dedicated to the memory of J. Schwinger     

Locating animals from their sounds and tomography of the atmosphere: experimental demonstration.

Calling animals are located using widely distributed receivers, and the sounds from the animals are used to map the sound speed and wind fields by means of tomography. In particular, two Red-Winged Blackbirds Agelaius phoeniceus are correctly located within a meter using recordings from five receivers spread over a 20 by 30 m region. The demonstration hinges on two new developments. First, a new algorithm for blindly estimating the impulse response of the channel is shown capable of estimating the differences in the time of first arrivals at two receivers. Since it is known that the first arrivals travel along nearly straight paths, the difference in time constrains the animal's location to a hyperboloid, and the animal is located by intersecting hyperboloids from many pairs of receivers. Second, in order to accurately find the intersection point and map the sound speed and wind fields using tomography, a nonlinear equation is solved. The new algorithm for blindly estimating the impulse response of a channel offers a new way for locating sounds and making tomographic maps of the environment without any requirement for a model for the propagation of sound such as is needed for focalization and matched field processing.     

Sequential streaming due to manipulation of interaural time differences

The effect of apparent spatial location on sequential streaming was investigated by manipulating interaural time differences (ITDs). The degree of obligatory stream segregation was inferred indirectly from the threshold for detecting a rhythmic irregularity in an otherwise isochronous sequence of interleaved "A" and "B" tones. Stimuli were bandpass-filtered harmonic complexes with a 100-Hz fundamental. The A and B tones had equal but opposite ITDs of 0, 0.25, 0.5, 1, or 2 ms and had the same or different passbands. The passband ranges were 1250-2500 Hz and 1768-3536 Hz in experiment 1, and 353-707 Hz and 500-1000 Hz in experiment 2. In both experiments, increases in ITD led to increases in threshold, mainly when the passbands of A and B were the same. The effects were largest for ITDs above 0.5 ms, for which rhythmic irregularities in the timing of the A or B tones alone may have disrupted performance. It is concluded that the differences in apparent spatial location produced by ITD have only weak effects on obligatory streaming.     

The Surface Energy of MgO: Multiscale Reconstruction from Thermal Groove Geometry

The surface energy of MgO is determined using experimental data collected from equilibrated thermal grooves circumscribing island grains. Local equilibrium assumptions at each groove require that the Herring equations be satisfied at each data site, thereby yielding a large and overdetermined system of equations involving the surface energy . This inverse problem is then solved using a new technique that is statistical in nature and multiscale in implementation. The resulting discrete solution represents a statistically significant representation of the surface energy of MgO as a function of surface orientation. Comparisons to results derived from a more traditional approach, along with suggested further applications, are discussed.     

Sex differences in voice onset time: a developmental study of phonetic context effects in British English

Voice onset time (VOT) data for the plosives /p b t d k g/ in two vowel contexts (/i a/) for 5 groups of 46 boys and girls aged 5; 8 (5 years, 8 months) to 13;2 years were investigated to examine patterns of sex differences. Results indicated that there was some evidence of females displaying longer VOT values than the males. In addition, these were found to be most marked for the data of the 13;2-year olds. Furthermore, the sex differences in the VOT values displayed phonetic context effects. For example, the greatest sex differences were observed for the voiceless plosives, and within the context of the vowel /i/.     

Spatial cues alone produce inaccurate sound segregation: the effect of interaural time differences

To clarify the role of spatial cues in sound segregation, this study explored whether interaural time differences (ITDs) are sufficient to allow listeners to identify a novel sound source from a mixture of sources. Listeners heard mixtures of two synthetic sounds, a target and distractor, each of which possessed naturalistic spectrotemporal correlations but otherwise lacked strong grouping cues, and which contained either the same or different ITDs. When the task was to judge whether a probe sound matched a source in the preceding mixture, performance improved greatly when the same target was presented repeatedly across distinct distractors, consistent with previous results. In contrast, performance improved only slightly with ITD separation of target and distractor, even when spectrotemporal overlap between target and distractor was reduced. However, when subjects localized, rather than identified, the sources in the mixture, sources with different ITDs were reported as two sources at distinct and accurately identified locations. ITDs alone thus enable listeners to perceptually segregate mixtures of sources, but the perceived content of these sources is inaccurate when other segregation cues, such as harmonicity and common onsets and offsets, do not also promote proper source separation.     

从物理看乐音的和谐--物理与音乐专题之一

"总想对你表白,我的心情是多么豪迈.……"(走进新时代) "五十六个民族,五十六枝花.……"(振兴中华) "五星红旗迎风飘扬,胜利歌声多么响亮!……"(歌唱祖国) "春天来了,大地在欢笑!……"(蓝色的多瑙河)