bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of the improvement in hearing Japanese speech while wearing earplugs advertised as enabling communication
Authors: Yokoya Toshitaka , Inoue Jinro , Kohata Shinji , Kawanami Shoko , Horie Seichi
Published: November 2016

Workers often refuse to wear earplugs because of the difficulty hearing conversations in noisy workplaces. Little research has been performed to explore whether multiple syllables of the Japanese language are difficult to hear through earplugs. New earplugs recently became available that could be used to communicate clearly in noisy workplaces and simultaneously prevent personal noise exposure. This study aimed to evaluate the hearing of speech using three types of earplugs in a noisy environment. The subjects were 10 people without hearing loss. We conducted this experiment in the anechoic room at the University of Occupational and Environmental Health, Japan. We set up a pink noise environment at 80 dBA, 85 dBA, and 90 dBA, and evaluated the hearing of speech with and without earplugs. The subjects were asked to distinguish standard Japanese words comprising two syllables recorded on a CD-ROM (TY-89) established for the evaluation of the fitness of hearing aids. If the speech level required for 90% intelligibility with those new earplugs was lower than that without earplugs, or lower than that with reference earplugs reported previously, the new earplugs can protect hearing and lead to good communication. A comparison of the new and reference earplugs will be discussed.
Thoughts on MIL-STD-1474E noise limits
Authors: Ahroon William A. , Flamme Gregory A.
Published: November 2016

Department of Defense Design Criteria Standard Noise Limits (MIL-STD-1474E), published in 2015, is a standard developed for the acquisition of military materiel specifies the maximum permissible noise levels produced by military systems and the test requirements for measuring these levels. It is intended for use by equipment designers and manufacturers, covering typical operational conditions and provides noise limits shall not be exceeded if the materiel is to be acceptable to the procuring activity. It is not intended to be used for health hazard assessments for personnel exposed to impulsive noises. Appendix B established the acquisition requirements for impulsive noise limits. Oddly, the standard allows the use of two different methods, although the U.S. Army must use a method that utilizes the Auditory Hazard Assessment Algorithm for Humans. This paper describes some obstacles in using this appendix for acquisition of weapons systems, including the curious use of two completely different methods for measuring impulsive noise limits, the middle-ear assumptions of the required Army method, and the limits of assumed risk of hearing loss from exposure to impulsive noises.
Ultrasonic tissue micro-engineering: Making tumor models for optimizing immuno-therapy
Authors: Wiklund Martin , Olofsson Karl , Carannante Valentina , Önfelt Björn
Published: November 2016

We demonstrate a method for tissue micro-engineering based on ultrasound-supported three-dimensional (3D) cell culture in a multi-well microplate. The method can be used for producing various tissue-mimicking 3D structures in parallel, and utilizes ultrasonic standing wave trapping forces inside hundred micro-wells in a multi-well microplate fabricated in silicon and glass. We have analyzed and optimized the driving parameters of the ultrasound transducer attached to the microplate, and we demonstrate the production of different micro-engineered tumor models, including micro-scaled 3D solid models of liver, kidney, and skin tumors. The tumor models have been analyzed with flow cytometry in order to investigate the difference between 2D and 3D cultures in expression of protein ligands susceptible to recognition by natural killer (NK) immune cells. We have also designed an image-analysis-based method for quantification of the amount of NK cells needed to defeat a tumor having a certain size, shape, and composition. Our results are important for optimizing future personalized immuno-therapy methods for the treatment of various cancer diseases.
Neutral core-shell particles under acoustic radiation force
Authors: Leao Jose P. , Lopes Jose H. , Silva Glauber T.
Published: November 2016

We theoretically analyze how a core-shell small particle can become nonresponsive under the acoustic radiation force in an ideal fluid. The particle is composed by a fluid core cloaked by an elastic or viscoelastic solid shell with considering its outer radius much smaller than the wavelength, e.g., the so-called Rayleigh scattering limit. By suitably choosing the core volume fraction (the core-to-shell volume ratio) one may suppress the radiation force. In case of a traveling plane wave, radiation force neutrality is related to scattering cancellation by the cloaking shell. However, neutrality is not achieved for absorptive cloaks. The somehow “intuitive” connection between scattering cancellation and radiation force suppression does not happen for a standing plane wave. Also, shell absorption does not change neutrality in this case. It is worth to mention that standing wave is the leit motiv of particle handling in different microfluidics applications. Several examples of radiation force neutrality are illustrated on a fluid core (air, fluorinert, and methanol) with a gold and polyethylene shell. In addition, we show that secondary radiation forces (Bjerknes force) in a many-particle system can also be suppressed by selecting an appropriate core volume fraction.
Temperature stable liquid gigahertz viscosity sensors by combining shear mode piezoelectric ScAlN thin film and AT-cut quartz crystal plate
Authors: Sano Ko-hei , Mori Takeshi , Karasawa Rei , Yanagitani Takahiko
Published: November 2016

We here propose the temperature stable liquid GHz viscosity sensors by combining shear mode piezoelectric thin film and AT-cut quartz crystal plate. In the ultrasonic viscosity sensors, longitudinal wave cannot be used because the longitudinal wave energy leaked into the liquid. Therefore, shear wave is required for the viscosity measurement. We recently reported new large shear wave piezoelectricity in the c-axis tilted ScAlN films. In this study, the resonator type viscosity sensor consisting of c-axis tilted ScAlN films (approximately 7 μm) grown on an AT-cut quartz crystal plate were fabricated. Because the thickness of AT-cut quartz crystal is large enough compared to that of ScAlN film, temperature coefficient of resonant frequency is approximately determined by the extremely temperature stable quartz crystal. This enable robust measurement for the external temperature change. Increase of the viscous penetration depth between the liquid and the resonator interface induces the decrease of resonant frequency. The change of liquid viscosity can be then determined by this frequency shift. We observed strong shear wave excitation at the 403 MHz by using a network analyzer in the air. When the sensor was immersed in the pure water, 50 kHz decrease of shear wave resonant frequency was clearly observed.
Dynamic measurement of microbubble compressibility and interactions in an acoustofluidic device
Authors: Memoli Gianluca , Baxter Kate O. , Fury Christopher R. , Jones Philip H. , Zeqiri Bajram
Published: November 2016

A key parameter for coated microbubbles in diagnostic and therapeutic applications is the non-linear response of their shell to acoustic pressures. Different measurements of this parameter exist, but most rely on the bubbles to be stuck on a surface or on the absence of acoustic excitation. In this work, we use the dynamic of coated microbubbles in an acoustofluidic device to measure the acoustic forces acting on them and the dynamic response of their shell to an increasing acoustic pressure. The device comprises of a microfluidic glass chip, where acoustical tweezers (operating in the range of 160-180 kHz) and optical tweezers can be used simultaneously. Comparing results from the calibrated optical tweezers, laser vibrometry and particle tracking allows a precise characterization of the acoustic field as a function of the driving voltage, at fixed frequencies and for pressures up to 4 kPa. Building on this result we extend the tracking technique to polymer-coated microbubbles and measure the acoustic forces acting on them over a larger range of pressures and frequencies (acoustic force spectroscopy). As pressure increases, we quantify secondary Bjerknes forces and present a dynamic characterization of microbubble compressibility with acoustic pressure. Finally, we present preliminary measurements on lipid-coated microbubbles.
Predicting effects of hidden hearing loss using signal detection theory
Authors: Oxenham Andrew J. , Wojtczak Magdalena
Published: November 2016

Recent physiological studies in animals have shown that noise-induced “temporary threshold shift” can result in a large and permanent loss of synaptic connections between the inner hair cells and the auditory nerve, without any measurable change in absolute thresholds. As audiometric absolute thresholds are the current clinical standard for diagnosing human hearing loss, this form of synaptopathy may remain undiagnosed, or hidden, with its perceptual consequences remaining unclear. Baseline expectations for perceptual consequences can be derived from a simple application of the principles of signal detection theory using a set of simplifying assumptions, such as independent and equal information from each auditory nerve fiber, and optimal integration of information. This approach shows that quite dramatic losses (e.g., 50%) lead to relatively small changes in predicted behavioral thresholds (1.5 dB in this case), which may not be easily detectable. However, synaptopathy that selectively affects specific neural populations, such as low-spontaneous-rate fibers, may result in larger and more measurable perceptual effects. Preliminary data from our lab also suggest that physiological measures, such as changes in wideband acoustic reflectance via the middle-ear muscle reflex, may provide a sensitive measure of synaptopathy in humans. [Work supported by NIH grant R01DC005216.]
Discrimination and identification of environmental sounds among people with hearing impairment
Authors: Yuno Yuuki , Matsubara Masaki , Tabaru Kei , Terasawa Hiroko , Hiraga Rumi
Published: November 2016

We report that people with hearing impairment (HI) can better discriminate environmental sounds than identifying the same sounds. In order to investigate the perception/recognition of environmental sounds by people with HI, researchers often choose identification task as a measurement tool. However, since identification ability is developed upon discrimination ability, the discrimination ability should be studied too. We used 9 environmental sounds as stimuli for both discrimination and identification tasks, and 16 participants with HI joined the experiment. In the discrimination task, the participants listened to the paired short stimuli, and reported the perceived difference. In the identification task, the participants listened to each stimulus and reported the name of the sound source. The order of discrimination and identification tasks is counterbalanced among the participants, and we also tested 10 people with normal hearing for comparison. The results showed a clear contrast between the discrimination and identification tasks by people with HI. People with HI outperformed in discrimination tasks (97.0 % correct answer on average) than in identification tasks (35.5 % correct answer on average). This means that people with HI can discriminate most of the sounds that they cannot identify, suggesting the potential for the acquisition of identification ability.
Human electrophysiology of endogenous auditory spatial attention
Authors: Ozmeral Erol J. , Eddins David A. , Eddins Ann C.
Published: November 2016

Whereas perceiving the location of a stimulus in space relies on unique bottom-up processing, focusing attention to that location requires the availability and use of separate higher-level processes. It is unclear from previous work how selective attention might mediate and possibly sharpen spatial tuning, as behavioral tasks often lack an unattended comparison, and electrophysiological tasks often lack an attended comparison. We measured evoked responses to changes in the location of continuous noise in the free field when young, normal-hearing listeners were either passively listening or explicitly attending to one speaker location. Stimuli were presented from 1 of 5 frontal loudspeaker locations in the horizontal plane for 1.6 s before switching to another loudspeaker without pause. To ensure active attention for certain blocks, listeners were directed to press a button at the onset of a sound presented from the target location. Results show evidence of both facilitation for attended locations and suppression for unattended locations when compared to passive listening, and hemispheric distribution of activity was hemifield specific. Together, the data provide electrophysiological measures of a listener’s left-right orientation and another step toward cortical models of auditory spatial attention.
Chord consonance represented in the long-lasting sustained activity in rat auditory cortex
Authors: Shiramatsu Tomoyo I. , Takahashi Hirokazu
Published: November 2016

Many sounds in the environment have a rich sound spectrum, which is related to the qualia of the sound such as consonance or dissonance of chords. However, the neural representation of chord consonance is not fully understood. Here, we targeted long-lasting, sustained activities in auditory cortex and investigated whether band-specific power or phase locking value (PLV) represent consonance of the chord consisting of two pure tones. A microelectrode array with 96 recording sites recorded local field potentials (LFPs) in the fourth layer of the auditory cortex of anesthetized rats in response to continuous pure tones and chords. From the LFPs, band-specific powers and PLVs were calculated in 5 bands (theta, 4—8 Hz; alpha, 8—14 Hz; beta, 14—30 Hz; low gamma, 30—40 Hz; high gamma, and 60—80 Hz). Then, differences of band-specific power and PLV (Δpower and ΔPLV) of a chord with respect to those of the higher-frequency composition tone of the chord were compared between consonance and dissonance. Consequently, Δpower was significantly smaller, and ΔPLV was significantly larger for consonance than dissonance, suggesting that the long-lasting, sustained activity in the auditory cortex is modulated according to the complex sound spectrum, such as consonance of the chords.
Investigating the contribution to anti-masking by the inhibitive networks in the dorsal cochlear nucleus: Modeling and simulation
Authors: Liu Tzu-Chi , Liu Yi-Wen
Published: November 2016

In psychoacoustics, masking happens when the perceptibility of a target sound is influenced by another sound, which is called the masker. The medial olivocochlear (MOC) reflex pathway, which receives information from the cochlear nucleus and gives feedback to the cochlea, has been said to modify the gain function of the cochlea and enhance the audibility of sounds in noise. This enhancement of audibility is referred to anti-masking. To simulate masking and anti-masking, a tone-in-noise stimulus is delivered to an integrated model comprised of a nonlinear model of cochlear mechanics and a leaky integrate-and-fire network describing the dynamics of the MOC pathway. In particular, the T-multipolar (TM) cell in the ventral cochlear nucleus is chosen to transfer signals to the MOC, and the conductance of the outer hair cell is adjusted by the MOC efferent output to simulate anti-masking. Further, the inhibition from the tuberculoventral cell in the dorsal cochlear nucleus to the TM cell is also included in the model so its influence on the auditory nerve rate-level curves can be investigated in the tone-in-noise condition.
Comparing auditory perceptual thresholds in pediatric and adult cochlear implant populations
Authors: O'Brien Gabrielle , DiNino Mishaela , Biesheuvel J. D. , Briaire Jeroen J. , Frijns Johan H. , Bierer Julie A.
Published: November 2016

It is well known that cochlear implant listeners show enormous variability in speech recognition performance, but the individual differences that affect outcomes are still poorly understood. The overall level and variability of psychophysical thresholds obtained with a focused electrode configuration may account for some of the variability in outcomes, as these measures might reflect the quality of the electrode-neuron interface. To date, psychophysical thresholds using direct stimulation have not been assessed in children. In this work, we compare such thresholds between pediatric and adult cochlear implant listeners. Thresholds were collected from 12 pediatric and 34 adult ears using a fast threshold sweeping method with both focused (partial quadrupolar) and broad (monopolar) electrode configurations. On average, both focused and broad thresholds were 4 dB lower in the pediatric population compared to the adult population. Intra-array variability in thresholds was found to be smaller in pediatric than adult populations for broad but not focused stimulation. Increased threshold observed for focused stimulation compared with broad, quantified as the ratio of focused to broad thresholds, did not differ significantly across populations. These results suggest that there may be differences in the quality of the electrode-neuron interfaces observed in pediatric and adult cochlear implant listeners.
How the sound adjustment process of cymbals affects their vibration and sound radiation characteristics
Authors: Kuratani Fumiyasu , Yoshida Tatsuya , Koide Toshio , Mizuta Taiji , Osamura Kozo
Published: November 2016

Cymbals are percussion instruments. They vibrate and radiate sounds when hit with a drumstick or when used in pairs and the sounds depend on the vibration characteristics. Cymbals are made through spin forming, hammering and lathing. The spin forming creates the domed shape of the cymbal, determining its basic vibration characteristics. The hammering and lathing produce specific sound adjustments by changing the vibration characteristics. In this study, we focus on how the hammering affects the vibration and sound radiation characteristics. The hammering produces many shallow dents over the cymbal’s surface, generating residual stresses in it. These residual stresses change the vibration characteristics. We perform finite element analysis of the hammered cymbal to obtain its vibration and sound radiation characteristics. In the analysis, we use thermal stress analysis to reproduce the stress distribution and then with this stress distribution we perform vibration analysis. The results show that the effect of thermal load (i.e., hammering) depends on mode: an increase or decrease in the natural frequency. The difference between the modes changes the peak frequencies and their amplitudes in the frequency response. As a result, the deflection shapes and their sound radiation efficiencies at the peak frequencies are changed.
Finite-difference time-domain analysis of the vibration characteristics of building structures using a dimension-reduced model
Authors: Asakura Takumi , Toyoda Masahiro , Miyajima Tohru
Published: November 2016

In order to accurately predict the vibration characteristics of buildings, wave-based numerical methods are effective from the viewpoint of the modeling accuracy of the physical mechanism and the detailed geometries of the simulated field. However, because of the performance of current PCs, the prediction of real-scale problems remains difficult. In order to address such problems, we herein propose a vibration simulation method for a beam-plate structure using a dimension-reduced modeling method. The target structure is modeled as a composite structure consisting of two-dimensional plate elements and one-dimensional beam elements, which are coupled based on the implicit finite-difference approximation scheme. By applying such a low-dimensional element, a faster simulation that requires less memory, as compared with a three-dimensional discretization scheme, is made available. To validate the method, the vibration characteristics obtained by the proposed scheme are compared to the measured results for model-scale and full-scale structure. The comparison of the measurement and simulation results suggest that the proposed method can be used to accurately simulate a multilayered building structure.
Incongruence in second language vowel perception and production
Authors: Thomson Ron I. , Munro Murray J.
Published: November 2016

Nearey’s work on double-weak theory has brought to the fore the conceptualization of native-language (L1) speech perception and production as autonomous subsystems. In second-language (L2) phonetics research, the perception-production relationship is also a central concern, although the facilitating and hampering effects of a previously learned phonological inventory must be taken into account (Flege, 2003). Some current views of L2 phonetic learning assume that a reorganization of perceptual knowledge normally comes first, and that production eventually falls into line with perceptual representations (Huensch, 2013; Thomson, 2011, 2013). However, the available data point to a number of complexities in the relationship that have yet to be accounted for. In the present report, we synthesize new data on vowel perception and production by English learners from a variety of L1 backgrounds. Among the key findings are that (1) perceptual training on vowels in particular phonetic contexts leads to very limited transfer of learning to new phonetic contexts, (2) perceptual accuracy only weakly predicts production accuracy, especially for cross-linguistically marked vowels, (3) word familiarity and frequency correlate with vowel production accuracy, and (4) elicitation techniques influence production accuracy. These issues are discussed in terms of the problems they pose for models of phonetic learning.
Unusual public voices
Authors: Assmann Peter F.
Published: November 2016

Terry Nearey has a long-standing interest in vocal properties that carry phonetic information and simultaneously contribute to voice quality. He has drawn attention to the perceptual importance of the relationship between time-averaged fundamental frequency (f0) and formant frequencies and shown how combinations of these properties conspire to produce unique and highly identifiable voices, such as that of the late television cook Julia Child, who had atypically low formants but f0 in the expected range; and the cartoon figure Popeye (played by Jack Mercer) who had relatively high formant frequencies but a normal f0 range. This talk will present examples from Terry’s collection along with acoustic analyses and a discussion of their perceptual implications.
Making decisions about modeling decision-making when analyzing speech perception data
Authors: Silbert Noah H.
Published: November 2016

Speech perception researchers are typically interested in, well, perception. But perception is not directly observable. An experimental participant hears (and maybe sees) a stimulus, but the researcher only observes the listener’s response (e.g., which button is pushed, how long it takes to push the button). Crucially, a listener’s response doesn’t directly, or solely, reflect perceptual processing; listeners’ responses also reflect what we might call response selection or decision-making. While there is a sizable sub-field in psychology devoted to the study of judgment and decision making, these issues are of more peripheral concern for speech perception researchers. Nonetheless, I will argue that it is important to take response selection into account when analyzing perception data. Terry Nearey is one of a small number of speech researchers who has consistently taken decision-making seriously when analyzing speech perception data. I will discuss a number of mathematical approaches to simultaneously modeling perception and response selection and how changes in modeled perception and decision-making predict distinct observable patterns in data. The importance of decision-making in the study of perception will be discussed and illustrated via a number of Terry Nearey’s studies as well as my own.
The perception of spontaneous speech: “Lo how complex”
Authors: Tucker Benjamin V.
Published: November 2016

While most of the speech that listeners encounter is produced during spontaneous conversation, researchers actually know very little about this type of speech. What we do now is that there is tremendous variability and complexity in spontaneous speech that is not found in laboratory styles of speech. These differences compound and present new challenges for speech researchers, and in this case speech perception. It is possible that the changes found in spontaneous speech are systematic; however, it is also possible that these changes increase the noise in the speech signal. The vast majority of recent research on spontaneous speech has focused on word recognition and has not focused on aspects of perception and how spontaneous speech impacts theories of speech perception. In this presentation, I provide several examples of the variability and complexity found in spontaneous speech. I explore some of the challenges spontaneous speech creates for models of speech perception. I also discuss some perception data on spontaneous speech which sheds some light on future directions in research on speech perception.
Vowel dynamics and sentence processing
Authors: Kewley-Port Diane , Fogerty Daniel
Published: November 2016

Throughout Terrance Nearey’s influential academic career, research on the acoustic properties, models and theories of vowels has been a major focus. Studies by Nearey and his colleagues demonstrated the importance of spectral change (VISC) in vowel identification, even for monophthongal vowels. This presentation describes our research on vowel dynamics inspired by VISC research. Starting with syllables, the auditory system can discriminate F1 and F2 formants transition differences very well. Further results using high-fidelity resynthesis with sentences revealed that formant discrimination thresholds are 50% smaller than differences observed for natural syllables. These results support that human perception is very sensitive to spectral information in dynamically changing vowels in sentences. A second line of research examined the role of vowel information in sentences using noise interruption paradigms. Based on traditional segment boundaries, vowels had a two-to-one perceptual advantage over consonants for recognizing words in sentences. Shifting boundaries to favor consonantal transitions revealed a large advantage for even small proportions of vowel information. Recent research has enhanced understanding of the interdependence between vowel dynamics and suprasegmental contours of F0 and amplitude for accurate speech recognition. Thus, dynamic information in vowels, both VISC and suprasegmental, is essential for sentence intelligibility.
Evaluation of crack parameters by a nonlinear frequency-mixing laser ultrasonics method
Authors: Mezil Sylvain , Chigarev Nikolay , Tournat Vincent , Gusev Vitalyi
Published: November 2016

Nonlinear acoustic methods are commonly used in crack detection because of their high sensitivity in comparison to linear ones. However, the dependence of the nonlinearities on the crack state can not only localize it but also provides information on its characteristics. We present a laser ultrasonic method, based on nonlinear frequency-mixing, to locally evaluate several crack parameters, including some, like the local crack elasticity, which are assessed uniquely by the present technique. Two laser beams, independently intensity modulated at two cyclic frequencies ωH and ωL(ωH>>ωL), excite the sample. For a large sinusoidal thermo-elastic stress generated by the low-frequency modulated laser beam, the crack oscillates between closed and open states. In the presence of this variation, nonlinear frequency-mixing ultrasonic components at frequencies ωH±nωL (n is an integer) are detected. By modifying the intensity of the laser beam modulated at ωL, we can influence the time spent in opened and closed state over a period (2π/ωL). The developed theoretical model demonstrates the dependence of the nonlinear components at ωH±nωL on the time spent by the crack in each state. Comparison between theoretical and experimental results offers a way to characterize some local crack properties, including its width and effective rigidity.
Nonlinear scattering of crossed focused ultrasonic beams in a constricted flow for the detection of a thrombosis
Authors: Kilen Emily S. , Johnson Theodore R. , Fisher Daniel J. , Korman Murray S.
Published: November 2016

Experiments performed at the USNA Acoustics Lab use turbulent flow to generate nonlinear scattering of mutually perpendicular crossed beams (f1 = 1.9 MHz, f2 = 2.1 MHz, 15 cm focal lengths) at the combination sum frequency component (f+ = 4 MHz). The object is to simulate blood flow through a constriction, and measure the nonlinear scattering downstream with a receiving circular plane array transducer (4 MHz) that rotates azimuthally in the plane of the transmitted beam axes about the intersection. Angular dependent Doppler shift (about f+), spectral broadening, skewness and kurtosis measurements vs. angle help predict the characteristics of the turbulence. The setup involves a 4 cm diameter polyethylene (0.5 mm thick) tube cut in two sections (22 cm upstream (a), 38 cm downstream (b)). The sections are mated with a special block union allowing one to insert individual thin orifice plates of different diameters. The far section ends are open but are connected through opposite side ports on (a) and likewise on (b) to in-phase and out of phase synchronized bellows pumps. The apparatus when submerged in a water tank generates pulsating turbulent flow. Nonlinear scattering is measured vs. orifice size. [See S. M. Mock (2013) and D. J. Fisher (2014), USNA Capstones.]
Complex acoustic intensity transmission through the air-water interface
Authors: Dall'Osto David R. , Dahl Peter H.
Published: November 2016

Sound transmission through the air-water interface occurs when there is a non-zero normal component of active and reactive acoustic intensity. Transmission occurs for both active intensity (pressure and particle velocity in phase) and reactive intensity (pressure and particle velocity out of phase), and depending on the proximity of the source to the surface these can convert from one form to the other. Intensity transmission through the interface is governed Chapman’s Law—which differs slightly from Snell’s law but is consistent with the requirement of phase continuity along the surface. Properties of intensity transmission through the air-water interface are examined using three examples: (1) Marine pile driving, where sound generated by the in-air portion of the pile is injected into the water-column, and sound generated underwater leaks into the air. (2) Transmission of far-field active and reactive intensity generated by aircraft, and how Chapman’s law or Snell’s law describe Doppler shifts. (3) The ability of a fish-catching bat to locate fish underwater with sonar, and how transmitted active intensity resonates with the swim-bladder of the fish generating a near-field that radiates into the air as active intensity. [Research supported by ONR.]
Model validation of rough surface scattering at a water/air interface using a hybrid parabolic equation model
Authors: Smith Kevin B. , Aslan Mustafa , Moss Geoffrey
Published: November 2016

Traditionally, ocean acoustic propagation models assume the sea surface can be treated as an idealized pressure release boundary. For flat surfaces, this can easily be accomplished through a variety of modeling techniques. Rough surfaces, however, introduce additional complexities in numerical models. For propagation models based on the parabolic equation that utilize split-step Fourier (SSF) algorithms, previous work has involved field transformational techniques to treat the rough surface displacements. Such techniques assume small angle scattering at the interface, which may not produce adequate numerical accuracy. An alternative approach is to model the physical water/air interface, and allow the higher order propagator functions of the parabolic approximation to more accurately model the rough surface scatter. However, the introduction of such large interface discontinuities have been known to introduce phase errors in SSF-based models. In this work, a previously developed hybrid split-step Fourier/finite-difference approach is implemented at the water/air interface. Results are compared with standard SSF smoothing approaches, as well as the pressure release field transformational technique, for simple rough surfaces. A finite element model is utilized to provide a benchmark solution and comparisons are made for both standard Dirichlet and explicit mixed media treatments of the air-water interface. Tradeoffs between accuracy and stability are discussed, as well as transmission across the water/air interface.
Seabed target discrimination using multistatic acoustic scattering data
Authors: Fischell Erin M. , Schmidt Henrik
Published: November 2016

One application for autonomous underwater vehicles (AUVs) is detecting and classifying hazardous objects on the seabed. We have been studying an alternative acoustic approach to this problem in which an acoustic source insonifies seabed targets while receiving AUVs discriminate targets based on features sensed in the resulting 3D scattered fields. The receiving AUVs have entirely passive sensing payloads, and therefore lower power draw and cost. When both the acoustic source and receiver are mobile, multistatic scattering data are collected. Using the OASES-SCATT scattering simulator, we studied how multistatic scattering data collected by AUV-based receivers around targets insonified by AUV-based sources might be used for sphere and cylinder target characterization in terms of target shape, composition, and size. The impact of target geometry on multistatic scattering fields is explored, and a target discrimination approach developed in which the acoustic source and receiver to circle the target with the same radial speed, collecting multistatic scattering data at constant bistatic angles. The frequency components of the multistatic scattering data at different bistatic angles are used to form probabilistic and machine learning models for target characteristics. New data are then classified using these models. [Work supported by ONR and Battelle.]
Point measurements of ambient biological noise before, during, and after multiple underwater detonation events over coral substrate off the southern coast of Oahu, Hawai
Authors: Farrell Dara M. , Shannon Lee H. , Dahl Peter H. , Dall'Osto David R.
Published: November 2016

Measurements were taken of background noise at the U.S. Navy's Pu‘uloa Underwater Detonation Range off the south coast of O‘ahu during a U.S. Navy underwater explosive training exercise in shallow water (10-18 m) where distance from the detonation site, charge size, and explosive composition were controlled. The autonomous recording unit was deployed approximately 1500 m from the detonation location. The combined data from the paired low (-220 dB re 1 V /μPa) and high (-170 dB re 1 V /μPa) sensitivity hydrophones gives an approximately 100 dB dynamic range view of each event. Each trial consisted of three replicate events per charge weight (2.2, 4.5, and 8.6 kg) for a total of nine explosive events over the coral substrate. An analysis of the background noise environment immediately before and after each replicate is presented using metrics such as spectral probability density. Results are considered in the context of typical coral reef noise including discussion of snapping shrimp noise (one of the dominant features of the soundscape) before and after each event. [Work supported by U.S. Pacific Fleet.]
Near-field localization of under water noise source based on matrix spatial filter with vector sensor array processing
Authors: Xueyan Wang , Shengguo Shi , Jie Shi
Published: November 2016

To detect the weak sources of interest area which are obscured by strong sources, a new algorithm of near-field localization of underwater noise source based on matrix filter is proposed. This algorithm use matrix filter as a pretreatment to filter array data of vector sensor, optimized design method is used to design the matrix filter, and then formulate the problem into a second-order cone programming model to calculate the matrix equation, which can strictly control the attenuation of stop band, and it can avoid increment of noise power by restrain the norm of matrix filter. With this filter matrix, a new covariance matrix is produced for the following beam-forming processing with vector sensor array. Compared with the previous work, this algorithm can accurately locate the weak sources of interest that are obscured by strong sources; in addition, higher location accuracy and spatial resolution, better spatial anti-aliasing performance, as well as stronger capability to distinguish the starboard and larboard benefit from using vector sensor array. The simulation and real data show that this algorithm can precisely locate the weak source of interest among some strong sources.
Absorption characteristics of micro-perforated panels using scale modeling and microflown impedance gun
Authors: Dance Stephen , Brown Simon , Ruegger Carl
Published: November 2016

A theoretical and experimental comparison of the absorption characteristics of micro-perforated panels was undertaken. The micro-perforated panels were designed using the Sheffield University Java based website, constructed from 0.3 m by 0.3 m of acrylic, the thousands of holes were laser cut. The panels were large enough to be tested using the microflown impedance gun as well as a new scale model reverberation chamber based at London South Bank University. The 1:10 scale model reverberation chamber was constructed from acrylic materials and used a 3-D printed dodecahedron sound source. Data acquisition was through a ¼” microphone connected through a Nexus preamplifier to a 24 bit 192 kHz sound card. MATLAB code was used to acquire and process the signal in accordance to ISO 354 including air compensation for high frequencies. Results will be presented for theoretical, scale, and impedance based measurement of the absorption coefficients for the micro-perforated panels.
Design of a compact spherical loudspeaker array for simulating accurate instrument directivities for concert hall measurement and auralization
Authors: Neal Matthew T. , Smallcomb Molly R. , Dick David A. , Vigeant Michelle C.
Published: November 2016

An omnidirectional sound source is often used as a repeatable source to measure impulse responses in concert halls to obtain room acoustics metrics. The limitation of using an omnidirectional source is that real sound sources, such as musical instruments, do not exhibit omnidirectional radiation patterns. For an orchestra, many instruments with unique directional radiation patterns are distributed across the stage. To achieve more realistic auralizations, a 20-element compact spherical loudspeaker array was constructed to simulate the frequency-dependent radiation properties of instruments. This loudspeaker array is capable of achieving a truncated third-order spherical harmonics representation of an instrument’s radiation pattern. Once the source is moved to different instrument locations around stage, frequency-dependent weighting factors for each driver are controlled to match the source’s radiation pattern to that instrument. Full three-dimensional impulse response measurements of the source were made to characterize the source’s directional performance. From these measurements, frequency-dependent gains were applied to determine the accuracy and frequency range of the directional reproduction, and the results for various instruments will be presented. The implementation of this source into an existing measurement setup for future measurements of U.S. and European concert halls will also be discussed. [Work supported by NSF Award 1302741.]
Musical instrument directivity database for simulation and auralization
Authors: Behler Gottfried , Shabtai Noam R. , Weinzierl Stefan , Vorländer Michael
Published: November 2016

A study of 41 modern and historical orchestral musical instruments was made recently. All instruments were played in an anechoic chamber and recorded simultaneously with an array of 32 microphones place on a sphere of 4.2 m diameter. The musicians were placed in the centre of the sphere and instructed to play chromatic scales covering the whole range of each instrument at two levels—very soft and very loud. From these recordings the directivity for steady tones has been derived. The radiation pattern is represented in the 4-th order spherical harmonics domain, using 25 coefficients and 31 third-octave frequency bands. For 7 instruments, acoustic source centering is applied in order to align the acoustic center of the sound source to the physical center of the microphone array using the center-of-mass approach [Ben-Hagai et al., JASA 2011] and using the phase symmetry approach [Shabtai and Vorländer, JASA 2015]. Analysis of the database is found in [Shabtai et al. JASA 2016 (submitted)]. From this analysis, a database has been created that will be available for scientific use soon. This database is recommended to be used in virtual reality applications to improve the sense of realism perceived by the user.
Subjective evaluation of sound diffusion in a surround hall
Authors: Jang Hyung Suk , Lim Hansol , Jeon Jin Y.
Published: November 2016

The effects of diffusing elements on sound field diffuseness were investigated by subjective evaluations using binaural impulse responses (BIRs) in seating areas in a surround hall. The room acoustical parameters as well as the number of peaks (Np) and local maxima within -20 dB of the amplitude of direct sound were investigated to evaluate the diffuseness in the halls. For the listening test, stimuli were selected to explore the combination of acoustic parameters and degree of diffusion. The music signals were convolved with the measured BIRs in different listening positions. Based on the listening test, it was found that positions close to the diffusers with a high scattering coefficient were preferred by the listeners.
Study of the perception of warmth in concert halls and correlation with room acoustics metrics
Authors: Sorensen Kristina M. , Vigeant Michelle C.
Published: November 2016

Challenges in concert hall acoustics research occur in bridging the domain between subjective attributes and objective metrics. Several studies have shown that the primary attributes associated with concert hall acoustic preference ratings are strength, clarity, and timbre. The purpose of this study was to investigate the correlation of warmth, which is closely associated with timbre, with the objective metric of bass ratio (BR), which is a measure of the ratio of acoustic information (such as reverberation time or strength) at low-frequencies to that at mid-frequencies. The stimuli for this study were simulated binaural room impulse responses (BRIRs) obtained in ODEON and convolved with a concise orchestral anechoic motif. The BRIRs were simulated using models of five European halls. A model of the Vienna Musikverein with multiple absorption settings was also used to achieve different values of BR within a single hall geometry. The stimuli were presented to participants over headphones and they were asked to rate warmth, low- and high-frequency reverberance on continuous five-point scales. Participants rated each of the attributes in separate sets to avoid potential bias in the ratings. A repeated measures analysis of variance was conducted to examine the relationship between the subjective ratings and BR.
A fundamental study of evaluating sound fields in performance spaces based on equal tempered scale
Authors: Matsuo Akiho , Hanyu Toshiki , Hoshi Kazuma
Published: November 2016

Generally, the reverberation times, energy decay curves, directional characteristics, and so on are analyzed in 1 octave bands or 1/3 octave bands for evaluating acoustic conditions in performance spaces. The center frequencies such as 1000 Hz are defined by engineering implication. However, these center frequencies are not always adequate for evaluating performance spaces because music is basically composed of musical scale like the equal tempered scale. Therefore, it is thought that it is reasonable to use center frequencies based on the equal tempered scale in order to evaluate performance spaces. Based on this idea, we calculated reverberation times and energy decay curves for 1/12 octave bands at which center frequencies are set by using the equal tempered scale. Directional characteristic of reflected sounds is an important factor for evaluating spatial impressions in performance spaces. Therefore, we measured the directional characteristics based on sound intensity in the 1/12 octave bands. Moreover, we focused on chord which is a combination of several musical tones, in other words, several 1/12 octave bands. We calculated energy decay curves and directional characteristics focusing on the chord. As a result, characteristic tendencies were obtained on the energy decay curves and the directional characteristics.
Autonomous mobile robot to improve sound environment for speech conversation
Authors: Kawai Shuhei , Uehara Masashi , Okawa Shigeki , Fukushima Manabu
Published: November 2016

This study pursues to improve sound environment for speech conversation by moving an articulation panel by a robot. We tried to move the articulation panel to behind of the listeners by a small robot to keep fixed distance from the listener. An optimal location of the articulation panel depends on the sound sources such as speech conversation or music appreciation. It is usually decided based on the sense of users and experts. If we use a room for the purpose of speech conversation, the articulation panel is placed behind the listeners. However, moving the articulation panel optimally is almost impossible in terms of economical and physical conditions. In recent years, robot technology for transportation is in progress widely. We attempt resolving these problem by robotics. The articulation panel is framed by wood to have absorption and reflection surfaces, and the robot has omni-wheels for ultra-pivot turn performance. It can turn the surface on the sound source by the rotation of the robot. The robot has four-wheel drive because it should have large stable range as to the purpose to carry objects. Several sensors are used such as an ultrasonic sensor and an infrared sensor to have robustness. As a result, we approached to improvement of sound environment by robotics.