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Journal of the Acoustical Society of America

Salvador Barrera-Figueroa
Microphones are typically calibrated in a free field at frequencies up to 40 kHz using primary and secondary methods. This upper frequency is sufficiently high as to cover most sound measurement applications related with airborne noise assessment. However, other applications such as measurement of noise emitted by ultrasound cleaning machines, failure detection in aeronautic structures, and the investigation of the perception mechanisms of ultrasound may require that the sensitivity of the microphone is known at frequencies up to 150 kHz...
October 2018: Journal of the Acoustical Society of America
Mark A Bee, Alejandro Vélez
Many animals communicate acoustically in large social aggregations. Among the best studied are frogs, in which males form large breeding choruses where they produce loud vocalizations to attract mates. Although chorus noise poses significant challenges to communication, it also possesses features, such as comodulation in amplitude fluctuations, that listeners may be evolutionarily adapted to exploit in order to achieve release from masking. This study investigated the extent to which the benefits of comodulation masking release (CMR) depend on overall noise level in Cope's gray treefrog ( Hyla chrysoscelis )...
October 2018: Journal of the Acoustical Society of America
Pablo L Rendón, Roberto Velasco-Segura, Carlos Echeverría, David Porta, Antonio Pérez-López, R Teo Vázquez-Turner, Catalina Stern
The Schlieren method has been used before to visualize weak shock waves radiated from the open ends of brass instruments, but no attempt has previously been undertaken, however, to measure the geometry of the radiated wavefronts using the Schlieren images. In this paper Schlieren visualization is used to estimate the geometry of the two-dimensional shock wavefronts radiated from the bell of a trumpet at different frequencies. It is observed that the geometry of the shocks does change with frequency, in the expected manner...
October 2018: Journal of the Acoustical Society of America
Milan Červenka, Michal Bednařík
This paper presents a theoretical study of the sound propagation in a waveguide loaded by an array of flush-mounted narrow side-branch tubes, forming a simple low-frequency reactive silencer. The individual tube-lengths and the distances between the adjacent tubes are optimized in order to maximize the minimum transmission loss over a given frequency range. The transmission properties of the silencer are calculated using the transfer matrix method, heuristic evolutionary approach is employed for the determination of the optimal parameters...
October 2018: Journal of the Acoustical Society of America
Jonathan H Siegel, Kren Rahbek Nørgaard, Stephen T Neely
Evanescent waves emerge from a small sound source that radiates into a waveguide with a larger cross-sectional area, but unlike planar waves, do not propagate far from the source. Evanescent waves thus contaminate in-ear calibration of acoustic stimuli. Measurements with an otoacoustic-emission (OAE) probe inserted at the entrance of long tubes of various diameters show a decline in the evanescent wave with distance from the source when advancing a probe tube through the OAE probe and into the long tube. The amplitude of the evanescent pressure increases with frequency and depends strongly on the diameter of the long tube...
October 2018: Journal of the Acoustical Society of America
Chengzhe Zou, Ryan L Harne
Physically reconfigurable, tessellated acoustic arrays inspired by origami structures have recently been leveraged to adaptively guide acoustic energy. Yet, the prior work only examined tessellated arrays composed from uniform folding patterns, so that the limited folding-induced shape change prohibits broad acoustic field tailoring. To explore a wider range of opportunities by origami-inspired acoustic arrays, here, piecewise geometries are assembled from multiple folding patterns so that acoustic transducer elements are reconfigured in more intricate ways upon array folding...
October 2018: Journal of the Acoustical Society of America
Hironobu Takahashi, Ryuzo Horiuchi
Airborne ultrasound has been used for various purposes, including object detection and pest repellent systems. Recently, it has been used in haptic technology for virtual reality. The safety of exposure to airborne ultrasound has been studied as its use has increased. Although airborne ultrasound cannot be directly perceived by humans, some research has found that exposure to very high sound pressure levels can harm the human body. Thus, quantitative characterization of airborne ultrasound is essential. To contribute to the safe use of airborne ultrasound, this paper established the acoustic standards in Japan in terms of sound pressure from 20 to 100 kHz...
October 2018: Journal of the Acoustical Society of America
Yunqiao Liu, Michael L Calvisi, Qianxi Wang
Encapsulated microbubbles (EMBs) are associated with a wide variety of important medical applications, including sonography, drug delivery, and sonoporation. The nonspherical oscillations, or shape modes, of EMBs strongly affect their stability and acoustic signature, and thus are an important factor to consider in the design and utilization of EMBs. Under acoustic forcing, EMBs often translate with significant velocity, which can excite shape modes, yet few studies have addressed the effect of translation on the shape stability of EMBs...
October 2018: Journal of the Acoustical Society of America
Kren Rahbek Nørgaard, Efren Fernandez-Grande, Søren Laugesen
The calibration of ear-probe microphones can increase the precision of calibrating stimulus levels in situ and of measuring acoustic responses from the ear. This paper proposes a methodology to measure the sensitivity of an ear-probe microphone, requiring only an acoustic coupler and a calibrated reference microphone. The input impedance of the coupler is measured, enabled by a preliminary acoustic Thévenin calibration of the ear probe, and the plane-wave transfer impedance of the coupler is calculated analytically...
October 2018: Journal of the Acoustical Society of America
H C Song, Gihoon Byun
The cascade of blind deconvolution and array invariant has been successful for localizing a single source, either a surface ship or a submerged source, using a vertical array without knowledge of the environment or source waveform in shallow water. In this letter, the blind deconvolution is extended to a two-source case where individual Green's functions are separately extracted by exploiting a distinct group of modes strongly excited at different source depths. The subsequent array invariant confirms that a surface ship and a towed source at 50-m depth can be simultaneously localized using a 56-m long vertical array in 100-m deep shallow water...
October 2018: Journal of the Acoustical Society of America
Astrid van Wieringen, Christ Glorieux
The objectives of the present study were to investigate the acoustical properties of the very high frequencies and/or ultrasound signals produced by a repellent device and to investigate potential adverse factors as a result of short-term exposure to these signals. Potential adverse effects were evaluated perceptually with 25 young and 25 middle-aged persons, all with normal hearing thresholds, in a quiet room using different outcome measures, including a 15-item survey presented before and immediately after each condition...
October 2018: Journal of the Acoustical Society of America
Elias Zea, Ines Lopez Arteaga
This brief communication exposes an overview of various wavenumber filters to separate the rail contribution to pass-by noise via the wave signature extraction method [Zea, Manzari, Squicciarini, Feng, Thompson, and Lopez Arteaga, J. Sound Vib. 409 , 24-42 (2017)]. It has been found that the originally proposed filters underestimate the rail noise at frequencies above 1.6 kHz due to the presence of higher-order wave families that is unaccounted for. The goal of this letter is thus to propose and examine different filter functions that can capture such waves, and to assess whether the rail contribution estimations can be improved...
October 2018: Journal of the Acoustical Society of America
Dorea R Ruggles, Alexis N Tausend, Shihab A Shamma, Andrew J Oxenham
The brain decomposes mixtures of sounds, such as competing talkers, into perceptual streams that can be attended to individually. Attention can enhance the cortical representation of streams, but it is unknown what acoustic features the enhancement reflects, or where in the auditory pathways attentional enhancement is first observed. Here, behavioral measures of streaming were combined with simultaneous low- and high-frequency envelope-following responses (EFR) that are thought to originate primarily from cortical and subcortical regions, respectively...
October 2018: Journal of the Acoustical Society of America
Miran Oh, Yoonjeong Lee
Real-time magnetic resonance imaging (MRI) speech production data have expanded the understanding of vocal tract actions. This letter presents an Automatic Centroid Tracking tool, ACT, which obtains both spatial and temporal information characterizing multi-directional articulatory movement. ACT auto-segments an articulatory object composed of connected pixels in a real-time MRI video, by finding its intensity centroids over time and returns kinematic profiles including direction and magnitude information of the object...
October 2018: Journal of the Acoustical Society of America
Mark D Fletcher, Sian Lloyd Jones, Paul R White, Craig N Dolder, Timothy G Leighton, Benjamin Lineton
Various adverse symptoms resulting from exposure to very high-frequency sound (VHFS) and ultrasound (US) have previously been reported. This study aimed to establish whether these symptoms are experienced under controlled laboratory conditions and are specific to VHFS/US. To do this, participants were exposed to VHFS/US (at frequencies between 13.5 and 20 kHz and sound pressure levels between 82 and 92 dB) and to a 1 kHz reference stimulus, both at 25 dB above their hearing threshold. The VHFS/US and reference stimuli were presented 4 times, each time for 3 min, during which participants performed a sustained attention task, rated their symptom severity, and had their galvanic skin response (GSR) measured to assess their level of anxiety...
October 2018: Journal of the Acoustical Society of America
Michael Reinwald, Quentin Grimal, Jacques Marchal, Stefan Catheline, Lapo Boschi
Mammals use binaural or monaural (spectral) cues to localize acoustic sources. While the sensitivity of terrestrial mammals to changes in source elevation is relatively poor, the accuracy achieved by the odontocete cetaceans' biosonar is high, independently of where the source is. Binaural/spectral cues are unlikely to account for this remarkable skill. In this paper, bone-conducted sound in a dolphin's mandible is studied, investigating its possible contribution to sound localization. Experiments are conducted in a water tank by deploying, on the horizontal and median planes of the skull, ultrasound sources that emit synthetic clicks between 45 and 55 kHz...
October 2018: Journal of the Acoustical Society of America
Yi Shen, Celia Zhang, Zhuohuang Zhang
A Bayesian adaptive procedure, the interleaved-equal-loudness contour (IELC) procedure, was developed to improve the efficiency in estimating the equal-loudness contour. Experiment 1 evaluated the test-retest reliability of the IELC procedure using six naive normal-hearing listeners. Two IELC runs of 200 trials were conducted and excellent test-retest reliability was found at both the group and individual levels. Using the same group of listeners, Experiment 2 compared the IELC procedure to two other procedures that required frequency-by-frequency testing...
October 2018: Journal of the Acoustical Society of America
Eunghwy Noh, Hunki Lee, Wonjong Chun, Won-Suk Ohm, Kyounghun Been, Wonkyu Moon, Woosuk Chang, Hongwoo Yoon
A fast computational method for modeling and simulation of large projector arrays is presented. The method is based on the array equations that account for the acoustic interaction among the projector elements as well as the individual characteristics of each projector. Unlike the existing solution method in which the acoustic interaction must be known a priori in the form of interaction impedance matrix Z , the present method seeks the solution of modified array equations through iterations without explicitly evaluating the Z matrix...
October 2018: Journal of the Acoustical Society of America
Jan Radosz, Dariusz Pleban
In many countries, ultrasonic noise is included in the list of factors harmful to health in the work environment. For the frequency range above 20 kHz, there is no clear and complete information on the factors influencing the result of a measurement of sound pressure level. Moreover, there are no current international standards for performing measurements of ultrasonic noise at work stations. This article presents a possibility for the adaptation of the existing measurement methods [e.g., ISO 9612:2009 (2009)] to the ultrasonic range...
October 2018: Journal of the Acoustical Society of America
Martina Guidetti, Thomas J Royston
Dynamic elastography methods-based on optical, ultrasonic, or magnetic resonance imaging-are being developed for quantitatively mapping the shear viscoelastic properties of biological tissues, which are often altered by disease and injury. These diagnostic imaging methods involve analysis of shear wave motion in order to estimate or reconstruct the tissue's shear viscoelastic properties. Most reconstruction methods to date have assumed isotropic tissue properties. However, application to tissues like skeletal muscle and brain white matter with aligned fibrous structure resulting in local transverse isotropic mechanical properties would benefit from analysis that takes into consideration anisotropy...
October 2018: Journal of the Acoustical Society of America
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