bluuebunny/crossref_metadata_2025 huggingface dataset:
Broadband transparent periodic acoustic structures
Authors: Orris Gregory J. , Layman Christopher N. , Naify Christina J. , Martin Theodore P. , Calvo David C.
Published: May 2013

The creation of acoustically transparent materials is of interest for enhanced energy focusing in metamaterial lenses, vibration isolation and structure concealment in underwater environments. It has previously been shown that metal pentamode metamaterials may provide water like behavior yet retain enough shear to provide structural stability. This is achieved through a periodic lattice with sub-wavelength cells. The current talk presents a study on the simulated and experimental behavior of other structural materials that operate similar to pentamode composites, which exhibit transparency in underwater conditions. Specifically, we examine a two-dimensional design composed of a honeycomb arrangement of fluid inclusions in a solid polymer background. Materials, designs and simulations are supported through both band structure calculations and transmission modeling of finite slabs of the device. Experiments are performed in a water-filled test tank and broad frequency behavior is examined. [Work supported by ONR.]
Underwater sound transmission through thin soft elastomers containing arrays of pancake voids: Measurements and modeling
Authors: Calvo David C. , Thangawng Abel L. , Layman Christopher N.
Published: May 2013

Measurement of underwater sound transmission through thin (~750 microns) layers of the soft elastomer polydimethylsiloxane (PDMS) containing microfabricated arrays of pancake-shaped cavities is presented. Cavities are 120 microns in diameter and 2.5 microns in height with a nominal lattice spacing of 300 microns. A sound transmission minimum is found at 282 kHz which agrees with predictions of a finite-element model of the array and the value for monopole resonance frequency of an air-filled single pancake cavity in unbounded PDMS. This resonance is a factor of 0.62 lower than the null that would occur for spherical cavities of equivalent volume. The width of the minimum is also significantly broader than that which would be obtained with spherical voids. Modeling results incorporate careful measurements of attenuation for both shear and compression waves in PDMS done in a separate effort. Acoustic transmission variation as a function of lattice spacing and the number of layers is discussed. We also present measurements of transmission through PDMS layers featuring randomly positioned (but not overlapping) pancake cavities to evaluate how the lattice constant (or lack thereof) affects sound transmission near the pancake resonance frequency or in higher acoustic bandwidths. [Work sponsored by the Office of Naval Research.]
A320 flight deck shape effect on turbulent boundary layer auto-spectrum
Authors: Collery Olivier , Etchessahar Manuel , Alaoui Miloud
Published: May 2013

The turbulent boundary layer excitation is one of the main sources of aircraft interior noise over a large frequency range and in particular in the flight deck where its geometry drives the physics of the turbulences. The present study investigates measured turbulent boundary layer auto-spectrum properties. For that purpose an A320 has been instrumented with 15 flush-mounted microphones on the upper right quarter of the flight deck. The flight test campaign has been performed in cruise conditions between 27,000 and 39,000 ft with Mach numbers from 0.7 up to 0.82. Analysis of measured data shows strong shape effect on the aerodynamic excitation near windows area. This study points out that advanced numerical tools are required to model these complex aerodynamic phenomena.
Multiband transmissions for underwater acoustic communication
Authors: Song Aijun , Badiey Mohsen
Published: May 2013

Underwater acoustic communication is important to a variety of scientific and commercial missions in the ocean, for example ocean exploration and monitoring. Due to hardware limitations, often limited bandwidth, for example, 6–7 kHz, has been used in underwater communication systems. In addition to high spectral efficiency, large bandwidth can also lead to increased data rates. When utilizing a large frequency band, frequency-division multiplexing, which refers to dividing an available frequency band into smaller sub-bands, is the common practice. We propose to use multiband transmissions for the underwater acoustic channel, where the wide frequency band is divided into multiple separated sub-bands. The sub-band is much wider than the sub-carrier in the orthogonal frequency-division multiplexing (OFDM). The former is several kilohertz in width while the latter is often only tens of hertz. During our experiment in Hawaii in 2011, high data rates were achieved through the use of multiband transmissions, combined with time reversal demodulation. In the meeting, we will present the receiver algorithms for single- and multi-source acoustic communication systems in the multiband transmission framework. Comparison between the multiband transmissions and OFDM schemes will be also discussed. [Work supported by ONR Code 322OA.]
Study on time reverse mirror in underwater acoustic communication
Authors: Jingwei Yin , Pengyu Du , Jianwen Shen , Longxiang Guo
Published: May 2013

Time reversal mirror (TRM) can adaptively match the sound channel without any prior knowledge. In this paper, active TRM, passive TRM and virtual TRM which are all based on a single array element and the application of TRM in the underwater acoustic communication including single-user communication and multi-user communication are studied. Single sensor TRM which has time compression performance lacks array processing space gain, however, it can meet the requirements for underwater acoustic communication nodes being in the pursuit of simple structure and low power consumption. It is verified that TRM could focus multipath signal and achieve real-time adaptive channel equalization through computer simulation and test results, which could suppress the inter-symbol interference(ISI) and improve the signal-to-noise ratio(SNR).
Acoustical Society of America R. Bruce Lindsay Award
Authors: Stride Eleanor P. J.
Published: May 2013

The R. Bruce Lindsay Award (formerly the Biennial Award) is presented in the Spring to a member of the Society who is under 35 years of age on 1 January of the year of the Award and who, during a period of two or more years immediately preceding the award, has been active in the affairs of the Society and has contributed substantially, through published papers, to the advancement of theoretical or applied acoustics, or both. The award was presented biennially until 1986. It is now an annual award.
Acoustical Society of America von Békésy Medal
Authors: Liberman M. Charles
Published: May 2013

The von Békésy Medal is presented to individuals, irrespective of nationality, age, or society affiliation, who have made outstanding contributions to the area of psychological or physiological acoustics as evidenced by publication of research results in professional journals or by other accomplishments in the fields.
Acoustical Society of America Gold Medal
Authors: Crum Lawrence A.
Published: May 2013

The Gold Medal is presented in the spring to a member of the Society, without age limitation, for contributions to acoustics. The first Gold Medal was presented in 1954 on the occasion of the Society's Twenty-Fifth Anniversary Celebration and biennially until 1981. It is now an annual award.
International Commission for Acoustics Early Career Award
Authors: Lokki Tapio
Published: May 2013

The ICA Early Career Award is presented at the Triennial Congress to an individual who is relatively early in his/her professional career (about 10–15 years of active career), who has contributed substantially, through published papers, to the advancement of theoretical or applied acoustics or both and who has been active in the affairs of Acoustics through his/her National Society, other National Society(ies), Regional or International organizations. The Award consists of an Award Certificate, a Medal, and an Honorarium.
Validation of adaptive rectangular decomposition for three-dimensional wave-based acoustic simulation in architectural models
Authors: Antani Lakulish , Chandak Anish , Wilkinson Matthew , Bassuet Alban , Manocha Dinesh
Published: May 2013

Computer-based simulation is an increasingly popular way to predict the acoustics of real-world architectural designs. Most commercial acoustic simulation tools are based on geometric techniques and cannot accurately model low-frequency diffraction and other wave phenomena. Numerical wave simulation techniques can model these effects, but are less commonly used, since they are compute- and memory-intensive, and cannot scale to large spaces. Moreover, it is challenging to ensure that numerical methods do not suffer from high dispersion errors. Recent techniques have begun to overcome these limitations. One such method is adaptive rectangular decomposition (ARD), which combines analytical solutions to the wave equation in rectangular subdomains with a finite difference stencil for interface handling between subdomains, resulting in high-performance wave simulation with low dispersion error. ARD, along with high-performance ray tracing, are available as part of Impulsonic’s IPL SDK, a software development kit that allows custom acoustic simulation tools to be easily built with state-of-the-art simulation technology. In this paper, we evaluate the performance and accuracy of the IPL SDK and ARD, by analyzing simulation results and comparing them against measurements obtained for real-world architectural designs.
Time-domain formulation of an edge source integral equation
Authors: Svensson U. Peter , Asheim Andreas
Published: May 2013

In computer simulations of sound in enclosures, diffraction components can be added to geometrical acoustics ones for increased accuracy. A computational problem with diffraction is the large number of higher-order terms that is generated. A recent frequency-domain edge source integral equation (ESIE) efficiently handles the sum of all higher-order diffraction for rigid, external scattering objects, while computing first-order diffraction separately. Here, a time-domain formulation of the same ESIE is presented. An initial version handles higher-order diffraction for separate scattering objects, such as stage ceiling reflectors, and the extension to general geometries is outlined. With this approach, in a first step, an incident transient sound field is computed at discretized edge points, including the outgoing directivity. In a second step, the effects of diffraction of arbitrarily high order is handled by solving the IE iteratively, yielding the complete edge source time signals. In a third step, the edge source signals are propagated to receiver points. Numerical issues will be discussed, including discretization strategies and how to handle shadow zone boundary singularities.
Behavioral responses of humpback whales to seismic air guns
Authors: Cato Douglas H. , Noad Michael J. , Dunlop Rebecca A. , McCauley Robert D. , Kniest Hendrik , Paton David , Salgado Kent Chandra P. , Jenner K. Curt S.
Published: May 2013

A study of the responses of humpback whales to seismic air guns is being conducted in Australian waters and two of four major experiments have been completed. It aims to assess the impact of seismic surveys on the whales and the effectiveness of ramp-up in mitigation. In separate trials, whales were exposed to a 20 cu in air gun, ramp-up in level from 20 to 440 cu in with an air gun array, and a “hard start” of 140 cu in. Trials exposing whales to air gun treatments were balanced by controls without air guns firing. Whales were tracked from land using theodolites. Behavioral observations were made from these land stations, from three small vessels, and from the source vessel. Vocalizing whales were tracked with an array of hydrophones. Dtags were attached to some of the whales. Observations were made before, during, and after exposure. Characterization of the sound field throughout the area and the exposure at each whale were determined from propagation measurements and recordings on the hydrophone array and several moored acoustic recording systems. Some preliminary results will be discussed. [Work supported by E&P Sound & Marine Life Joint Industry Program and the U.S. Bureau of Ocean Energy Management.]
Enhancement effect of ultrasound-induced microbubble cavitation on branched polyethylenimine-mediated vascular endothelial growth factor 165 (VEGF165) transfection
Authors: Tu Juan , Li Qian , Zhang Chunbing , Zhang Dong
Published: May 2013

Angiogenesis is a complex process that is mediated by growth factor. One isoform of the vascular endothelial growth factor, VEGF165, has been reported to be a dominant mediator and regulator of angiogenic process. Branched polyethylenimine (bPEI) has been widely used as a non-viral delivery vector for gene therapy. HEK 293T cells, mixed with bPEI:VEGF165 complexes with different N/P ratios, were exposed to 1-MHz ultrasound (US) pulses. The enhancement effect of microbubble inertial cavitation (IC) on bPEI-mediated VEGF165 transfection was systemically investigated, in an effort to optimize transfection efficiency using low nitrogen:DNA phosphate (N/P) ratios. The results show that: (1) Microbubble IC activity can be quantified as an IC “dose” (ICD) and will be affected by US parameters; (2) DNA transfection efficiency initially increases with the increasing ICD, then tends to saturate instead of achieving a maximum value while ICD keeps going up; (3) the measured ICD, sonopration pore size, and cell viability exhibit high correlation among each other; and (4) microbubble IC activity has less cytotoxicity than bPEI, although a combinatorial effect of IC activity and bPEI can be observed on cell viability. All the results indicated that ICD could be used as an effective tool to monitor and control US-mediated gene/drug delivery effect, and it is possible to optimize bPEI-mediated VEGF transfection efficiency with relatively low N/P ratios by employing appropriate US parameters.
Time-resolved high-speed fluorescence imaging of bubble-induced sonoporation
Authors: Versluis Michel
Published: May 2013

The uptake of drugs through a cell membrane is enhanced by the use of bubbles and ultrasound. Little is known about the physical mechanisms underlying the uptake at short timescales. Here we study the bubble-assisted uptake of propidium iodide (PI) by endothelial cells at a millisecond timescale using high-speed fluorescence imaging. Single microbubbles were insonified at a driving frequency of 1 MHz and at acoustic pressures varying from 200 to 1200 kPa for a duration of 10 and 100 cycles. At a pressure of 200 kPa and 10 cycles, 50% of the cells showed uptake of PI, and this percentage increased to 90% for a pressure of 400 kPa. At a pressure of 1200 kPa all cells showed uptake of PI. The high-speed fluorescence recordings revealed that a localized pore in the cell membrane is formed right at the position of the bubble. Uptake was observed within several milliseconds after insonation and the size of the induced pore was found to be dependent on the bubble radius. Furthermore, the inflow of PI is diffusion-driven. The pore is formed temporarily and closes within several seconds after the ultrasound exposure.
Elucidating the effects of low-intensity ultrasound on mesenchymal stem cell proliferation and viability
Authors: Shah Nirali , Morsi Yosry , Manuelpillai Ursula , Barry Tim , Manasseh Richard
Published: May 2013

The effects of low-intensity ultrasound (LIUS) on the proliferation, viability and extracellular matrix (ECM) production of mesenchymal stem cells (MSCs) were investigated. Continuous-wave ultrasound was applied at 1 MHz and and 350 mW/cm2 to microwells, using a LIUS system assembled in the laboratory. Needle hydrophone mapping showed that pressure amplitudes ranged from 0.015 MPa at the well edge to 0.080 MPa at the center. The LIUS group received US for 10, 20, and 30 min/day for one week. Assays were performed daily. Relative to control, 10 and 20 min LIUS very significantly stimulated MSC proliferation and ECM synthesis, while 30 min LIUS had a significant adverse effect. The phenomenon that LIUS accelerates MSC proliferation, but only for appropriate exposures, has been noted previously in the literature. However, the actual relation between the physical forces generated by the LIUS and this phenomenon remains unknown. The fluid flow pattern created by LIUS was studied by injecting dye in the well and Eckart-streaming-like motions were observed, while thermal effects were negligible. By employing LIUS with appropriate focusing and parameters, it might be possible to exploit MSCs for tissue engineering, independently of biochemical stimuli, and in a highly spatially organized manner.
“SonoBandage” a transdermal ultrasound drug delivery system for peripheral neuropathy
Authors: Langer Matthew , Lewis Sabrina , Fleshman Shane , Lewis George
Published: May 2013

Peripheral neuropathy (PN) is a difficult disease to manage. Symptomatic treatment focuses primarily on pain relief, using NSAIDs, opioids, tri-cyclic antidepressants, and selective serotonin norepinephrine reuptake inhibitors. There is potential for ultrasound transdermal drug delivery to improve the quality of care provided to patients with PN, since it is well-suited to peripheral nerves which are close to the skin. In addition, targeted delivery avoids many of the systemic consequences of taking a drug. We developed a wearable ultrasound drug delivery system called “SonoBandage” that combines low-impedance miniaturization of ultrasound transducer, RF electronics, and battery power supply, with a novel hydrogel coupling bandage loaded with salicylic acid NSAID. The design of the SonoBandage allows the device to be used over a range of ultrasound frequencies (0.1–3 MHz), intensities (0.1–3 W/cm2), and durations (0.25–4 h) increasing system flexibility for drug delivery protocols. The SonoBandage with NSAID was evaluated on a bench-top model with freshly harvested porcine skin and synthetic biomimetic human skin membrane (Millipore Inc). Across the n = 40 samples studied, salicylic acid drug flux was increased by 2–20x as compared to control samples (p < 0.01) after 1–4 h of ultrasound treatment. SonoBandage has potential to be used as a practical NSAID delivery platform for peripheral neuropathy.
All-optical nonlinear frequency—Mixing acoustics of cracks
Authors: Gusev Vitalyi , Chigarev Nikolay , Mézil Sylvain , Tournat Vincent
Published: May 2013

Recent advances in all-optical evaluation of nonlinear cracks are reviewed. In experiments, the nonlinear acoustic waves are initiated by the absorption of radiation from a pair of laser beams intensity-modulated at two different frequencies. The detection of the acoustic waves at mixed frequencies, absent in the frequency spectrum of the laser intensity, is achieved by optical interferometry or deflectometry. The high contrast in crack imaging achieved by remote optical monitoring of the nonlinear acoustic processes is due to the strong dependence of the optoacoustic conversion efficiency on the state of the crack. The highest acoustic nonlinearity is observed in the transitional state of the crack, which is intermediate between the open and the closed ones. Several crack parameters can be estimated from the measurements of the dependence of the acoustic spectrum on the pump laser intensity. One-dimensional theory of the nonlinear frequency-mixing photo-acoustic crack imaging is presented. The theory relates experimental observation of the large number of mixed frequencies to strong bi-modular nonlinearity of the crack. The theory provides guidelines for the understanding of the dependence of the spatial resolution of this technique on the laser power and on the choice of a particular mixed-frequency component for the crack imaging. [Work supported by ANR project ANL-MEMS ANR-10-BLAN-092302.]
Improving the focal quality of the time reversal acoustic noncontact source using a deconvolution operation
Authors: Anderson Brian E. , Ulrich Timothy J. , Le Bas Pierre-Yves
Published: May 2013

The time reversal acoustic noncontact source (TRANS) utilizes time reversal (TR) from several transducers arranged in a cavity to focus energy onto a solid surface to allow inspection of that surface. The advantage of TRANS is that multiple transducers may be used to increase the amplitude of the focused energy onto the surface and potentially allow interrogation of nonlinear surficial features such as cracks and delaminations. TR is known to be a matched signal process and therefore is limited in the temporal fidelity and spatial compression of the focused energy. Fortunately, using a deconvolution operation in conjunction with TR [or inverse filter similar to Tanter et al. (J. Acoust. Soc. Am. 108, (2000), 223–234)] can greatly improve the quality of the spatial focusing as well as increasing the temporal fidelity. Visualizations of the impact of the deconvolution operation will be presented to provide insight into the increased quality of the spatial focusing along with results from using the deconvolution operation in conjunction with TRANS. [Work supported by Institutional Support (LDRD) at the Los Alamos National Laboratory.]
The effects of the transducer beam properties on the ultrasonic geometrical characterization of periodically corrugated surfaces
Authors: Liu Jingfei , Declercq Nico F.
Published: May 2013

Periodically corrugated structures are common in many technological applications, and in most cases, the geometry of these corrugated structures are crucial for the designed functionality. As an effective nondestructive characterization method, an ultrasonic imaging technique is investigated in this work for the purpose of accurately characterizing the geometry of periodic corrugations. Among many factors that affect the imaging quality the properties of the transducer beam dominate. The effects of the spatial and spectral properties of transducer beams on the accurate characterization of the characteristic dimensions of corrugations are investigated in details both theoretically and experimentally. The possibility to accurately characterize the corrugation characteristic dimensions, the condition for accurate characterization, and the quantitative relationship between the characterization accuracy and the beam parameters are given. The ways to avoid the diffraction effects and reduce possible errors are also discussed. Experimental results are compared with optical measurements and good agreement is obtained. Both the general principles developed theoretically and the practical techniques proposed can work as a useful guidance for similar work.
Measuring the acoustic response of a compartment fire
Authors: Abbasi Mustafa Z. , Wilson Preston S. , Ezekoye Ofodike A.
Published: May 2013

Rescue teams have a small window of time to locate a downed firefighter. Their task is made more difficult due to low visibility, smoke, toxic gases, and high temperatures. In the United States, most firefighters are equipped with a Personal Alarm Safety System (PASS) device that emits an alarm sound, when the firefighter becomes incapacitated. Rescue teams can then follow this sound to the source to locate the downed firefighter. While the PASS device has been enormously successful, anecdotal evidence has shown it fails in some interesting scenarios. For example, cases have been recorded where firefighters inside the building were unable to hear the signal, whereas those outside heard it clearly. To explain these cases, and to improve the signal used by the PASS device, it is necessary to understand sound propagation in the fireground environment. This paper will present acoustic transfer measurements inside a laboratory compartment fire, simulating a fire in a residential structure. The research aims to understand how the developing temperature gradient and smoke layer influences sound propagation. A secondary goal is the development and validation of finite element models of fireground acoustics. [Work supported by U.S. Department of Homeland Security Assistance to Firefighters Grants Program.]
Some simulations of the effect of varying excitation parameters on the transients of reed instruments
Authors: Silva Fabrice , Debut Vincent , Guillemain Philippe , Kergomard Jean , Vergez Christophe
Published: May 2013

This paper considers the simulation of self-sustained oscillations in reed and brass instruments, based on a compact continuous-time formulation of the sound production mechanism. The control parameters such as the mouth pressure and the player's embouchure, but also the acoustic resonator and the reed, may vary with respect to time, allowing the analysis of transient and non-stationary phenomena like changes of regime. A particular attention is first given to staccato notes, with comparison of the evolution of the instantaneous frequency in simulations to theoretical and experimental results. This shows the importance of using realistic control parameters on the onset of the oscillations. When the acoustic resonator is modeled using a modal expansion with non-stationary resonance frequencies and damping, it is also possible to simulate and study slurs and musical effects like the wah-wah, gaining some insight on the mechanisms involved.
Direct numerical simulations of the recorder in two and three dimensions
Authors: Giordano Nicholas
Published: May 2013

Direct numerical solutions of the compressible Navier-Stokes equations have been used to study various aspects of sound production in the recorder. A custom algorithm implemented on a parallel computer has enabled us to calculate tones and produce visualizations of the air flow near the labium in both two and three dimensions. In three dimensions, we have observed how the attack portion of the tone and the spectrum at long times depends on the relative alignment of the channel and labium. We also describe subtle differences in the process of vortex shedding in two as compared to three dimensions.
Outline proposal for a good practice guide on the evaluation of human response to vibration from railways in residential environments
Authors: Moorhouse Andy , Waddington David , Peris Eulalia , Woodcock James , Sharp Calum , Sica Gennaro
Published: May 2013

The paper will present outline proposals for a good practice guide for the evaluation of human response to vibration from railways in residential environments. The context is the need to increase the proportion of freight carried by railways in Europe while avoiding additional disturbance from vibration to populations living nearby. Within this context, the European funded project CARGOVIBES is developing the good practice guidelines to assist in the evaluation of potential disturbance. In the guide, it is proposed to include descriptions of the adverse response, primarily annoyance and sleep disturbance. The proposal is to use measured or predicted vibration metrics in conjunction with dose-response relationships to quantify potential adverse impact to residents. To this end, measurement and assessment of vibration will be considered, for example, the equipment, locations, mounting, and a description of the data to be acquired. The latest information on dose-response relationships will then be reviewed. Finally, various national limits for vibration will be evaluated against new scientific evidence on dose-response relationships.
Study on the annoyance of high frequency noise at industrial workstations
Authors: Smagowska Bozena E.
Published: May 2013

The aim of the study was subjective assessment of the acoustic environment of persons exposed to high frequency noise at workstations. The study based on the survey regarding the annoyance of this type of noise which was conducted among 52 operators of equipment for the production of platform gratings. The study covered workstations, where acoustic measurements confirmed the presence of high frequency noise (in the frequency range from 10 to 20 kHz). During work at these workstations, the value of the equivalent sound pressure level in one-third octave-bands center frequencies of 10, 12.5, and 16 kHz occurs within the range of 81–103 dB and exceeds the admissible value defined for these frequency bands. The results of the study indicated that 92% of respondents are exposed to noise the whole time of the shift. All respondents wear hearing protection. Most of the employees describe the noise as: buzzing, insistent, high-pitched squeaky, and whistling. Respondents unanimously consider related noise levels as: loud, impeding communication, highly strenuous, and tiring. The highest number of points on a scale corresponding to noise annoyance was achieved by terms: horrible, very, persistently, and firmly.
Comparison of discomfort caused by two kind of backup alarm
Authors: Brocolini Laurent , Léger Lucie , Parizet Etienne , Verlhac Jean-Marie , Carniel Xavier
Published: May 2013

Nowadays used on most of construction vehicles, tone backup alarm causes a strong discomfort among resident citizens. To solve this problem, “CETIM” (Mechanical Industries Technical Centre) decided to characterize and test another kind of alarm. This one is called “Cri du Lynx” in french (Lynx scream) because of its particular sound looks like a white noise. A previous study showed that the average sound level of the noise-alarm detectability is 67 dB (A) while it is 64 dB (A) for the tone-alarm (in a 80 dB(A) background noise). However, the noise-alarm could be used if it is less disturbing than the tone-alarm. The present work aims to compare the discomfort caused by exposure to tone and noise back-up alarms. About 50 people rated two times the discomfort caused by 11 sound environments. Each sound environment consisted of a site construction sound environment set at about 65 dB (A) mixed with a sequence of tone or noise alarm set at 56, 59, 62, 65, or 68 dB(A). One of the 11 stimuli had no alarm. Through an ANOVA it can be said if the kind of alarm and/or the sound level has an influence on the discomfort.
If a tree falls in a forest, can you hear it?
Authors: Weichert Max P.
Published: May 2013

Anthropogenic noise, from slowly rotating/reciprocating machinery, contributes immensely to environmental low-frequency noise below 100 Hz. This poses an acoustic low-energy problem as our technology offers no effective passive method for remediation. While attention is given to negative impact on human health and ecosystems, we still know and publicly do too little about it. Technical standards in Europe are A-weighted measurements that disregard actual energetic contributions of low frequencies. Different aspects of low-frequency sound have been illuminated by complementing acoustic measurements with findings from technical acoustics, bioacoustics, and human medical science. Sound pressure levels (SPL) were measured from 2.5 Hz to 20 kHz. The measurement setup consisted of SINUS Soundbook quadro (2.3 Hz– 22 kHz; linear@0 dB; ±0.1 dB tolerance; 1 Hz high-pass enabled), 1/2-in. Preamplifier/Free-Field Microphone (3.15 Hz– 20 kHz: ±2.0 dB; 5Hz–10 kHz: ±1.0 dB). Signals were processed with SINUS Driver version 5.1.0.8 and Samurai version 2.0.134. SPL in quiet forest [during 60 s: LZ,eq = 59.3 dB; LA,eq = 29.5 dB(A)] were compared to a quiet university room [during 60 s: LZ,eq = 74.4 dB; LA,eq = 28.2 dB(A)]. Healing properties of felid purrs produced with strong frequencies at an SPL between 30 and 60 dB suggest a general correlation of low-frequency background noise levels and health. Perhaps nature knows better than we do.
Nocturnal vibration from high numbers of freight trains leads to fragmented sleep
Authors: Smith Michael G. , Croy Ilona , Hammar Oscar , Ögren Mikael , Persson Waye Kerstin
Published: May 2013

There are an increasing number of freight trains on the European railway networks, and this growth has been facilitated through use of the available night time periods. Freight trains are particularly problematic with regards to generation of low frequency vibration and noise which has the potential to propagate to nearby homes and influence the sleep of residents. To investigate the potential impact we conducted a laboratory trial on 24 young healthy persons to ascertain physiological and psychological reactions to nocturnal vibration and noise from freight traffic, and to examine differences between gender and noise sensitivity. Nights with low (0.0102 m/s2) and high (0.0204 m/s2) peak weighted vibration amplitudes and low (20) and high (36) number of train passages were simulated with noise levels being of the same order between nights. Polysomnography was used to record sleep stage and EEG arousals and awakenings. Event related cardiac activations were analyzed using ECG recordings. Questionnaires were administered in the evenings and mornings to obtain subjective sleep parameters. Sleep was more fragmented during nights with higher vibration amplitudes and number of events. Furthermore, heart rate response was higher in the high vibration condition. Results from the subjective data showed less discrimination between nights.
Soundscape-focusing on resources
Authors: Schulte-Fortkamp Brigitte
Published: May 2013

In contrast to many other environmental problems, noise pollution continues to grow, and it is accompanied by an increasing number of complaints from people exposed to the noise. The growth in noise pollution involves direct, as well as cumulative, adverse health effects. It also adversely effects future generations, and has socio-cultural, aesthetic, and economic effects. Therefore, the concept of noise annoyance needed to be broaden to an integrated environmental, psychosocial, and socioeconomic assessment of the community situation to reach a more realistic basis for environmental impact and health risk assessments. Soundscape research represents a timely paradigm shift in that it combines physical, social, and psychological approaches and considers environmental sounds as a “resource” rather than a “waste” to satisfy human needs and wants. Moreover, balancing between the expertise from people living in respective areas and acoustic measurements, architectural planning will lead to a new understanding of a concept of an environment under “noise control” as soundscape suggests exploring noise in its complexity, its ambivalence, and its approach toward sound and quality of life.
Comparative auditory biomechanics probed by otoacoustic emissions
Authors: Bergevin Christopher , Dong Wei , Carney Laurel , Velenovsky David S. , Bonine Kevin E. , Jarchow James L.
Published: May 2013

Since Kemp's discovery in 1978, otoacoustic emissions (OAEs) have provided valuable scientific and clinical tools for the study of the ear. For example, OAEs can provide objective measures of sensitivity and selectivity over the frequency range of “active” hearing. Given the universality of OAEs across the kingdom Animalia, comparative studies can reveal how various morphological factors affect peripheral auditory transduction and thereby what information is encoded for higher level cognition. Motivated by the complexity of cochlear mechanics and the many unknowns that currently exist, the present study describes OAEs stemming from two non-mammalian groups whose auditory periphery is relatively simpler than that of mammals: several lizard genera (Heloderma, Tiliqua, Agama, and Tupinambis) that exhibit significant relative differences in tectorial membrane structure, and a highly vocal bird species (Melopsittacus undulatus). By utilizing recent improvements in OAE measurement and analysis strategies combined with quantitative anatomical measures (e.g., number of hair cells), these data shed new light upon emission generation mechanisms and how such tie back to a given species' ability to encode ecologically relevant sounds. Furthermore, these data serve to inform theoretical models of auditory biophysics by clarifying what roles various morphological features do (or do not) play.
Active processes and sensing in the cochlea
Authors: Grosh Karl , Meaud Julien
Published: May 2013

One key question in the biophysics of the mammalian cochlea is determining the relative contribution to cochlear amplification by the two active processes present in the outer hair cell, namely prestin-based somatic motility and hair bundle (HB) motility. In the biological cochlea, these two effects are intimately coupled as HB force generation is linked to calcium-dependent adaptation of the transduction current and somatic force generation is driven by the depolarization caused by the same transduction current. To separate these effects, we construct a global mechanical-electrical-acoustical mathematical model of the cochlea. The global cochlear model is coupled to linearizations of nonlinear somatic motility and HB motility. We find that the active HB force alone is not sufficient to power high frequency cochlear amplification while somatic motility can perform this task. We discuss the limitations to this mathematical approach along with existing seminal experiments and proposed experiments (both in the cochlea and in the auditory nerve) to map future directions for uncovering the micromechanical contributions to the system level response of the cochlea. Describing the relation between the microfluidic flow stimulating the inner hair cell HB and the active processes in the cochlea and is an important future research direction. [Support: NIH-NIDCD.]
Amplitude modulation detection by human listeners in reverberant sound fields: Effects of prior listening exposure
Authors: Zahorik Pavel , Anderson Paul W.
Published: May 2013

Previous work [Zahorik et al., POMA, 15, 050002 (2012)] has reported that for both broadband and narrowband noise carrier signals in a simulated reverberant sound field, human sensitivity to amplitude modulation (AM) is higher than would be predicted based on the acoustical modulation transfer function (MTF) of the listening environment. These results may be suggestive of mechanisms that functionally enhance modulation in reverberant listening, although many details of this enhancement effect are unknown. Given recent findings that demonstrate improvements in speech understanding with prior exposure to reverberant listening environments, it is of interest to determine whether listening exposure to a reverberant room might also influence AM detection in the room, and perhaps contribute to the AM enhancement effect. Here, AM detection thresholds were estimated (using an adaptive 2-alternative forced-choice procedure) in each of two listening conditions: one in which consistent listening exposure to a particular room was provided, and a second that intentionally disrupted listening exposure by varying the room from trial-to-trial. Results suggest that consistent prior listening exposure contributes to enhanced AM sensitivity in rooms, but that it is not the sole determinant of the enhancement. [Work supported by the NIH/NIDCD.]
Effects of targeted pinna occlusion on pinna/spectral cues to localization in the median plane
Authors: Musicant Alan , Baudo Robert
Published: May 2013

Auditory localization accuracy (in humans) in the median sagittal plane has been attributed, by some authors, to an effect of “spectral notches” that occurs in the frequency region of 4–8 kHz. Another possibility for decrements in vertical plane localization accuracy has been overlooked. Roffler and Butler (1967) and Hebrank and Wright (1974) both demonstrated that removal or absence of sound frequencies above about 8 to 10 kHz led to decrements in vertical plane localization accuracy. They did this by using carefully selected types of band pass or band limited noise. A reduction in accuracy of auditory vertical localization by occluding all or part of the pinna has been known for many years [Gardner and Gardner (1973)]. We have previously reported results that demonstrate disruption in accuracy with various partial pinna occlusions [ARO (2012)] that differs from results reported by Gardner and Gardner. We now have data that seems to indicate that the reduction in localization accuracy occurs, in part, because of disturbances in high frequency regions (above about 8 to 10 kHz) and that disruptions in “spectral notches” (4–8 kHz) has little to no effect upon vertical plane localization.
Release from masking through spatial separation in distance in hearing impaired listeners
Authors: Westermann Adam , Buchholz Jörg M.
Published: May 2013

It is widely accepted that speech intelligibility improves as a speech signal and interfering masker are separated spatially in azimuth. In a previous study [Westermann et al. IHCON (2012)] a similarly strong improvement was found for normal hearing (NH) listeners when target and masker are separated in distance. In this study speech reception thresholds (SRTs) were measured for 16 hearing impaired (HI) listeners using the Listening in Spatialized Noise-Sentences Test (LiSN-S) and the Coordinate Response Measure (CRM). Acoustic scenarios were auralized via headphones using binaural room impulse responses recorded in an auditorium. In the first scenario, the target was presented at a distance of 0.5 m from the center of the listener’s head and the interferer at a distance of 0.5 m or 10 m. In a second setup, the interferer’s location was fixed and the target’s location was varied. HI listeners showed a substantial release from masking as target and interferer were separated in distance. This effect was consistent for both LiSN-S and CRM, but less pronounced than for NH listeners. This study suggests that distance related cues play a significant role when listening in complex environments and are also to some extent available to HI listeners.
Exploring auditory gist: Comprehension of two dichotic, simultaneously presented stories
Authors: Iyer Nandini , Thompson Eric R. , Simpson Brian D. , Brungart Douglas S. , Summers Van
Published: May 2013

Cherry (1953) showed that when listeners were asked to selectively attend to one ear in a dichotic listening task, they were able to identify gross attributes of the signal in the unattended ear, suggesting that listeners may be able to capture the “gist” of an auditory stream even when they are asked to ignore it. This experiment explored the extraction of auditory “gist” by investigating the amount and nature of the semantic information stored in memory for later recall. In the experiment, listeners heard two dichotically presented stories; they were directed to: (1) listen to one of the two stories and answer yes-no questions about that story (Directed condition), (2) not directed (Undirected condition) and answer questions about one or both stories, and (3) listen to one of the stories and answer questions about the unattended story (Misdirected condition). Results suggest that listeners can recall the main ideas of both stories in the undirected attention condition significantly better than chance, but that their performance falls substantially below the level achieved in the directed attention condition. These findings are consistent with studies of visual gist processing, suggesting that global features, rather than details, are perceived even before attention is focused on the auditory streams.
Spectral integration of interaural time differences in auditory localization
Authors: Le Goff Nicolas , Buchholz Jörg M. , Dau Torsten
Published: May 2013

This study investigates how the auditory system integrates spatial information across frequency. In experiment 1, discrimination thresholds for interaural time differences (ITDs) were measured as a function of both reference ITD and center frequency (CF) of noises with bandwidth of one ERB. In addition, discrimination thresholds were also measured as a function of CF for different values of interaural coherence (IC) typical of sounds in realistic acoustic environments. For both high ICs and small reference ITDs, discrimination thresholds were lowest for CFs between 700 and 1000 Hz. For smaller ICs and larger reference ITDs, this dominance region shifted towards lower CFs. A conceptual localization model was developed that used the variance of the ITD thresholds to optimally weight the contribution of the individual frequency bands before spectral integration. In experiment 2, the model was tested by asking listeners to align a broadband noise signal with an ITD that was fixed across frequency onto a broadband noise target with different ITDs in individual 1 ERB-wide subbands. The results were consistent with both the model predictions and the shift of dominance range observed in experiment one.
Shifts in the judgment of distance to a sound source in the presence of a sonic crystal
Authors: Spiousas Ignacio , Etchemendy Pablo E. , Calcagno Esteban , Eguia Manuel C.
Published: May 2013

The ability of subjects to estimate the distance to a sound source in a room relies on the integration of a number of different cues: sound intensity level, direct-to-reverberant energy ratio, spectral content and binaural cues, among others. This work examines how the perception of auditory distance is modified for a particular sound field: the transmitted field of an acoustic source through a sonic crystal slab in a semi-reverberant room. A series of experiments were performed comparing the egocentric distance to a sound source passing and not passing through the sonic crystal, using an acoustical virtual environment whereby some of the auditory distance cues could be manipulated. The results obtained show that the presence of the sonic crystal introduces significant shifts on the auditory distance perception. These shifts are correlated with the spatial and spectral variation of the acoustical properties of the sonic crystal. Also, it was possible to determine the relative influence of the manipulated cues (intensity, binaural, and reverberation).
Validating a binaural head for use in jury testing
Authors: Charbonneau Jeremy E. , Novak Colin , Ule Helen
Published: May 2013

A test procedure for use in loudness perception tests must be created to completely describes a phenomenon while at the same time minimizing jury listening fatigue. One contributor to this fatigue is the amount of time necessary for the test subject to experience all the required signals. Head and torso simulators have been used for years as a means to reliably quantify the acoustic performance of a product while avoiding the influence of listener bias and fatigue. This procedure not only controls the test parameters but also removes any human error that may occur. The purpose of this investigation is to qualify a head and torso simulator for use in loudness investigations. The objective of this experiment is to correlate the results from using this equipment to human subject results for high resolution experiments on directionality of loudness. Comparisons are also made from the directionality results at various listening angles including a listener facing a sound source.
Development of an underwater binaural head model
Authors: Bailey Christopher A. , Aaronson Neil L.
Published: May 2013

The human brain has difficulty localizing sound in aquatic environments, where the acoustical properties of water greatly impede the mechanisms by which the brain interprets binaural signals. In this experiment, a hollow steel sphere with antipodal hydrophones is exposed to noise bursts in an underwater environment. The sphere can be filled with various materials to alter the apparatus’ rigid qualities. Interaural time and level differences (ITDs and ILDs, respectively) are calculated from recordings of these noises and compared to a theoretical model for sound propagation around a non-rigid head in an effort to better characterize binaural hearing in underwater surroundings. While the theoretical behavior of sound diffracting around a rigid head has been well documented, the similar problem involving a flexible head has largely been left to experimental methods due to the computational complexity of the task. In the current study, a new computational model, capable of predicting ITDs and ILDs for sounds encountering a non-rigid sphere in diverse environments, is used. Both the model and the experiment will be introduced in this presentation. The findings have significant implications for the future development of reliable methods for improving sound localization in underwater environments, for instance for recreational divers.