Sample discrimination of frequency differences with distracters

This study examined the effect of the type and frequency range of remote frequency distracters on sample discrimination of frequency differences (SD-F). For baseline SD-F conditions, normal-hearing listeners judged frequency differences between pairs of target tones drawn from Gaussian frequency distributions near 2000 Hz. In experiment 1, the distracters were pairs of random-frequency tones, fixed-frequency tones, or noise bands, with one distracter above and one below the target region. Three frequency separations of targets and distracters were tested, none overlapping the target region. Effects of fixed-frequency or noise-band distracters were small compared to that of random-frequency distracters, which drove performance to near chance. In experiment 2, dominance of the low-frequency distracter was supported by the effects of changing distracter level, by presenting only the higher- or lower-frequency distracter, and by the pattern of weights derived from trial-by-trial responses. Performance recovered only when the lower-frequency distracter was attenuated 40-50 dB relative to the targets. In experiment 3, all stimulus distributions were shifted 2 octaves higher in frequency; the stronger influence of the distracter frequency below the target remained. The results demonstrate the importance of both stimulus variability and frequency relationships in the interaction of targets and distracters for SD-F.     

Synchronized and noise-robust audio recordings during realtime magnetic resonance imaging scans

This letter describes a data acquisition setup for recording, and processing, running speech from a person in a magnetic resonance imaging (MRI) scanner. The main focus is on ensuring synchronicity between image and audio acquisition, and in obtaining good signal to noise ratio to facilitate further speech analysis and modeling. A field-programmable gate array based hardware design for synchronizing the scanner image acquisition to other external data such as audio is described. The audio setup itself features two fiber optical microphones and a noise-canceling filter. Two noise cancellation methods are described including a novel approach using a pulse sequence specific model of the gradient noise of the MRI scanner. The setup is useful for scientific speech production studies. Sample results of speech and singing data acquired and processed using the proposed method are given.     

Obtaining calibrated sound pressure levels from consumer digital audio recorders

Audio recording of environmental sound is an increasingly efficient method for autonomously sensing many ecological and anthropogenic processes. The increasing capabilities of consumer digital audio recorders (DARs), especially increases in storage capacity and reductions in power consumption, enable continuous audio recordings exceeding 1 month in duration with packages that are relatively small and inexpensive. To augment the ability of these systems to document the range of sounds present at a location, this paper examines two methods for calibrating recorders to measure sound levels. Compressed audio recorded by a DAR can be processed to yield relatively consistent measures of one-third octave band L_eq values within a limited frequency and dynamic range. This was evaluated by synchronizing data with a Type-1 sound level meter. The calibration is stable over a 23 day deployment outdoors with wide variation in ambient temperature and humidity. When considering aggregate acoustic metrics over time or a wide bandwidth such as an hourly A-weighted L₅₀, the results can be quite accurate (within 1 dBA).     

Interference effects from inclusive resonance production

If pions produced at high-energy reactions are decay products of narrow resonances, Bose interference effects at small invariant pion-pion masses are model-independently calculable from (inclusive) resonance production cross sections. We find that the π^?π^? correlations due to the analogue of the Hanbury Brown-Twiss effect are narrower than those currently observed, the latter being due to more complicated interferences.     

无线激光通信音频传输实验

设计了无线激光通信音频传输实验系统.在发射端采用对90 MHz载波信号调频方式调制放大信号后,再对半导体激光器进行强度调制;在接收端光信号由光电探测器转换为电信号,电信号经中频放大器、变频器和鉴频器解调出原始信号,原始信号再经功率放大器放大后由示波器接收.测量了实验系统音频传输的幅频特性、动态特性和延迟特性.实验结果表明:由于采用二次调制,系统抗干扰能力强,接收灵敏.     

Evaluating the maximum playback sound levels from portable digital audio players

To assess the maximum sound levels that may be experienced by young people in Canada from modern digital audio players, this study measured nine recent models of players and 20 earphones. Measurement methodology followed European standard BS EN 50332. Playback levels ranged from 101 to 107 dBA at maximum volume level. Estimated listener sound levels could vary from 79 to 125 dBA due to the following factors: (i) earphone seal against the ear, (ii) player output voltage, (iii) earphone sensitivity, and (iv) recorded music levels. There was a greater potential for high sound levels if intra-concha "earbud" earphones were used due to the effect of earphone seal. Simpler measurement techniques were explored as field test methods; the best results were obtained by sealing the microphone of a sound level meter to the earphone using a cupped hand and correcting for the free field response of the ear. Measurement of noise levels 0.25 m from the earphone showed that a bystander is unlikely to accurately judge listener sound levels.     

The effect of speechreading on the speech-reception threshold of sentences in noise

The monaural speech-reception threshold of sentences in noise, here defined as the 50% correct-syllables threshold, was measured for a female speaker with and without speechreading via a video monitor. The additional visual information resulted in a 4.6-dB lower threshold for a group of 12 young subjects and in a 4.0-dB lower threshold for a group of 18 elderly subjects compared to auditory presentation alone.     

Interference from nonlocal double-slit with pseudo-thermal light

We perform an interference experiment in which a pseudo-thermal light beam illuminates two spatially separated apertures, whose superposition at the same place forms a double-slit. The experimental result exhibits a typical double-slit interference fringe in the intensity correlation measurement, in agreement with the theoretical analysis by means of the property of the second-order spatial correlation of field of the thermal light.     

激光莫尔干涉谱投影信息提取

分析了真实火箭喷焰的激光莫尔干涉谱,并提取其投影信息,重建了密度场。使用自制的大口径、高灵敏度莫尔偏折仪采集真实火箭喷焰的莫尔条纹图;采用傅里叶变换对莫尔条纹展开技术处理,获得了莫尔条纹的相位分布。根据莫尔条纹边缘提取背景,进一步获得背景相位分布。变形莫尔条纹的形变量通过求相位差获得,进一步提取轴向任意截面的投影信息。应用基于偏折投影的“简单自相关代数迭代重建算法(SSART)”层析流场。等间隔取8个方向的投影进行迭代,重建了截面密度分布图。结果发现,根据火箭喷焰的莫尔条纹,采用傅里叶变换相位展开技术,可以方便地提取任意截面的投影信息。应用SSART技术可以重建截面密度分布。因此,基于偏折投影的“SSART”算法是一种优良的非线性偏折层析重建算法。     

Informational masking of speech in children: effects of ipsilateral and contralateral distracters

Using a closed-set speech recognition paradigm thought to be heavily influenced by informational masking, auditory selective attention was measured in 38 children (ages 4-16 years) and 8 adults (ages 20-30 years). The task required attention to a monaural target speech message that was presented with a time-synchronized distracter message in the same ear. In some conditions a second distracter message or a speech-shaped noise was presented to the other ear. Compared to adults, children required higher target/distracter ratios to reach comparable performance levels, reflecting more informational masking in these listeners. Informational masking in most conditions was confirmed by the fact that a large proportion of the errors made by the listeners were contained in the distracter message(s). There was a monotonic age effect, such that even the children in the oldest age group (13.6-16 years) demonstrated poorer performance than adults. For both children and adults, presentation of an additional distracter in the contralateral ear significantly reduced performance, even when the distracter messages were produced by a talker of different sex than the target talker. The results are consistent with earlier reports from pure-tone masking studies that informational masking effects are much larger in children than in adults.     

An electronic audio delay system

It is frequently desirable to be able to delay audio frequencies by times ranging from several milliseconds to hundreds of milliseconds. Although several methods have been developed to achieve this, most of them employ electromechanical delay systems. The article describes an all-electronic technique of delaying acoustic signals; experimental work on the system has established its feasibility.     

EDXRF with an audio digitizer

We utilized an audio digitizer in energy‐dispersive X‐ray fluorescence (EDXRF) with a silicon drift detector and achieved a full width at half maximum (FWHM) of 178 eV at Mn Kα (92‐µs peaking time). To confirm the ability of EDXRF with an audio digitizer, we also examined energy versus channel number linearity and output count rate. We applied it to EDXRF analysis of (ZnCd)S : Ag and showed a proper energy versus channel number linearity from 5.9 keV (Mn Kα) to 26.1 keV (Cd Kβ). And, the maximum output count rate of more than 10 kcps was obtained with 23‐µs peaking time (296‐eV FWHM). Copyright © 2011 John Wiley & Sons, Ltd.     

Interference between different photons from two incoherent sources

Intensity interference fringes are observed by using two incoherent light-emitting diodes. It is verified that even an incoherent light interferes with another one.     

Interference effects of radiation emitted from nuclear excitons

Hyperfine Interactions - The interpretations of the magnetic Mössbauer spectra (MMS) of five synthetic, Fe-rich P21/c clinopyroxenes along the ferrosilite-enstatite (Fs-En) join, and of one...     

基于量子干涉效应的多能级系统自发辐射研究

本文了一个多能级系统的量子干涉效应,该能级中三个相邻分离能级通过一相干驱动场与一个低能级耦合,同时通过真空模与另一低能级耦合。     

稀疏阵列交叉波束相干信号空间功率合成（英）

以稀疏阵相干信号干涉合成原理为基础,建立了相干信号空间功率合成数学模型。基于合成效率的概念,推导分析了交叉波束下波束交叉角度与目标点合成效率的关系。设计了栅基实验,对实验中栅格尺度的选定原则进行了推算分析,为利用计算机无失真地复现多点源功率合成能量分布规律打下了理论基础。通过仿真分析了波束交叉角度对有效功率点分布的影响。结果表明,在多点源与目标点等距、各点源频率相同、极化方向一致的情况下,目标点合成效率仅与空间中各点源之间夹角有关。当波束交叉时,有效功率点密集度与波束交叉角度有关。     

平面反射镜表面散射光干涉

激光束照射到表面被粘污的反射镜上会产生干涉环,入射光束和反射光束在被粘污表面产生散射光干涉.随着入射角的变化,光束在反射镜玻璃片内光程改变,引起干涉环从中心冒出或缩进,干涉环级数的变化与入射角的平方成正比.     

稀疏阵列交叉波束相干信号空间功率合成（英）

以稀疏阵相干信号干涉合成原理为基础,建立了相干信号空间功率合成数学模型。基于合成效率的概念,推导分析了交叉波束下波束交叉角度与目标点合成效率的关系。设计了栅基实验,对实验中栅格尺度的选定原则进行了推算分析,为利用计算机无失真地复现多点源功率合成能量分布规律打下了理论基础。通过仿真分析了波束交叉角度对有效功率点分布的影响。结果表明,在多点源与目标点等距、各点源频率相同、极化方向一致的情况下,目标点合成效率仅与空间中各点源之间夹角有关。当波束交叉时,有效功率点密集度与波束交叉角度有关。