bluuebunny/crossref_metadata_2025 huggingface dataset:
Buckling as a source of sound, with application to the modeling of cicada sound generation
Authors: Pierce Allan D. , Hughes Derke , Edoh Kossi , Katz Richard A. , Koch Robert M.
Published: May 2013

A basic model of a ribbed finite plate is first considered, with the plate connected to a parallel surface by a nonlinear spring. When individual ribs are placed under compression, the linearized version of the model predicts eventual exponential growth of the transverse displacement when the compressional load exceeds the buckling load. The nonlinear spring, however, stops this growth and a subsequent oscillation ensues. The anatomy of the cicada is, of course, much more complicated, and the basic model is extended to give a mathematical formulation of the model proposed by Bennet-Clark and Daws (J. Exper. Biol. 1999) for the Cyclochila australasiae (a relatively large species of cicada), with explicit elasto-mechanical parameters, a principal objective being the computational prediction of the observed far-field waveforms. Possible explanations are advanced for the anatomical cause of the nonlinear springs. Further extensions of the theory are applied to the development of mathematical models for species of cicadas (considerably smaller) commonly found in the United States.
Nature of nonlinear mechanisms in the generation and propagation of sound in the cicada mating call
Authors: Hughes Derke , Edoh Kossi , Pierce Allan
Published: May 2013

Experiments and analyses (Hughes et al., J. Acoust. Soc. Am. 2009) on the relationship of body surface displacements with external acoustic pressure measurements while cicadas are generating mating calls resulted in the conclusion that the relationship is substantially nonlinear. The present analysis assesses whether the propagation through the air is nonlinear propagation. Suspicion that such might be the case is suggested by the fact that the sound levels at distances of the order of several meters from a sounding cicada are as high as 90 dB at distances of the order of several meters. Computational results are reported in the present paper that indicate that nonlinear effects are not important for propagation of typical cicada frequencies of 10 kHz over a radial distance interval beginning 2 cm and ending at 10 m. A suggested explanation is based on the observation that the displacement of the body surface varies with position over the surface. The time history of displacements at different points is not as repetitive during successive tone burst generations as is the total volume displacement of the surface. This is consistent with the observation that buckling of the long ribs in the tymbals is the ultimate cause of the surface displacement vibrations.
Speed of sound of fatty and fibrosis liver measured by 80-MHz and 250-MHz scanning acoustic microscopy
Authors: Yamaguchi Tadashi , Inoue Kenta , Mamou Jonathan , Kobayashi Kazuto , Saijo Yoshifumi
Published: May 2013

Early detection of hepatitis is critical for proper patient management and improving disease prognosis. Ultrasound imaging is ideally suited for early-stage assessments, but conventional ultrasound images based on backscatter do not display quantitative tissue information because conventional ultrasound lacks essential modeling of the complex interaction between ultrasound and liver tissue in normal and diseased states. Therefore, speed-of-sound (SOS) measurements were obtained from three types of rat livers (normal, fatty, and fibrosis). Livers were harvested, fixed, and embedded in paraffin; a single 10-µm thin section was obtained using a microtome and placed on a microscope slide. A scanning acoustic microscope incorporating transducers operating at 80- and 250-MHz center frequencies was used to scan the 10-µm section. An adjacent 4-µm thin section was stained with H&E (normal and fatty livers) or Azan (fibrosis livers). The SOS measured with both transducers displayed the same trend: SOS in fatty liver was lower than in normal liver and SOS in fibrosis liver was higher than in normal liver. SOS differences were greater at 250 MHz because of the improved spatial resolution, which allowed choosing region-of-interests containing only fat or fibrosis tissue. These initial results also were used to correlate the pathologic state with the SOS.
Sound speed estimation in single cells using the ultrasound backscatter power spectrum
Authors: Strohm Eric M. , Kolios Michael C.
Published: May 2013

The acoustic properties of single cells such as their size, sound speed and attenuation are known to change depending on the type, state, or disease progression of a cell. Typically, ultrasonic pulse echo methods on adherent cells are used. We propose using the ultrasound backscatter power spectrum on cells in suspension to extract the acoustic parameters. When the ultrasound wavelength is on the same order as the dimensions of the cell, periodically varying minima and maxima occur throughout the power spectrum that depend on the sound speed and density of the object and the surrounding fluid, respectively. The ultrasound parameters can be determined by comparing the measured spectrum to a theoretical scattering model. We measured the backscattered ultrasound signals from single MCF7 breast cancer cells in suspension using a 200 MHz transducer. The cell diameter was determined through simultaneous optical imaging. The sound speed was calculated by adjusting the parameters in the scattering model until a good fit of the spectral features between the model and measured agreed. The sound speed from single cells found to vary between 1540 to 1580 m/s when the density was fixed at 1050 kg/m3.
Spatial specificity and sensitivity of passive cavitation imaging for monitoring high-intensity focused ultrasound thermal ablation in ex vivo bovine liver
Authors: Haworth Kevin J. , Salgaonkar Vasant A. , Corregan Nicholas M. , Holland Christy K. , Mast T. Douglas
Published: May 2013

Passive cavitation images (PCIs) generated from scattered acoustic waves are a potential technique for monitoring lesion formation during high-intensity focused ultrasound (HIFU) thermal ablation. HIFU lesion prediction by PCIs was assessed in ex vivo bovine liver samples (N = 14) during 30-s sonications with 1.1-MHz continuous-wave ultrasound (1989 W/cm2 estimated spatial-peak intensity). Treated samples were sectioned, optically scanned, and the HIFU lesions segmented based on tissue discoloration. During each insonation, a 192-element, 7-MHz linear array (L7/Iris 2, Ardent Sound) passively recorded emissions from a plane containing the HIFU propagation axis oriented parallel to the image azimuth direction. PCIs were formed from beamformed A-lines filtered into fundamental, harmonic, ultraharmonic, and inharmonic frequency bands. Lesion prediction was tested using binary classification of local tissue ablation based on thresholded PCIs, with spatial specificity and sensitivity of lesion prediction quantified by the area under receiver operating characteristic curves (AUROC). Tadpole-shaped lesions were best predicted by harmonic emissions (AUROC = 0.76), prefocal lesions were best predicted by harmonic or ultraharmonic emissions (AUROC = 0.86), and cigar-type focal lesions were best predicted by fundamental and harmonic emissions (AUROC = 0.65). These results demonstrate spatial specificity and sensitivity when predicting HIFU lesions with PCIs. [Work supported in part by NIH grants F32HL104916 and R21EB008483.]
Active control of axial and centrifugal fan noise
Authors: Sommerfeldt Scott D. , Gee Kent L.
Published: May 2013

Both axial and centrifugal fans are used to cool information technology (IT) equipment. These fans generate noise that can be annoying to their users, particularly the tonal noise that can be radiated. Work has focused on developing a method to attenuate the tonal noise associated with both of these types of fans. A compact system is used, whereby control sources are placed in close proximity to the fan. A genetic algorithm has been implemented to determine optimal source configurations. The attenuation associated with some configurations is found to be much more sensitive to error than others. For a given configuration, by using a relatively simple point source model it becomes possible to identify optimal near-field error sensor locations, which results in a compact noise control solution that provides significant global attenuation of the radiated tonal noise. This paper will review progress that has been made to apply this method to both axial and centrifugal fans. Experimental results confirm that it is feasible to achieve significant global control using this method.
Low frequency sound absorption of resonators with flexible tubes
Authors: Simon Frank
Published: May 2013

Classically, passive acoustic liners, used in aeronautic engine nacelles to reduce radiated fan noise, have a quarter-wavelength behavior, thanks to perforated sheets backed to honeycombs (SDOF, DDOF). So, their acoustic absorption ability is naturally limited to medium and high frequencies because of constraints in thickness. To drastically improve their capabilities to the lowest frequencies, the combination with active control systems or the using of foam architecture have shown an interest, but the industrial application is tricky (i.e., problems of fouling, robustness). A possible approach is to carry out a perforated panel resonator with flexible tube bundles to shift the resonance frequency to a lower frequency by a prolongation of air column length (Yadong Lu et al., Internoise 2007). This paper describes theoretically this concept that allows a significant change in the acoustic impedance due to the large thickness of the resistive and reactive material and the coupling with the surrounding cavity. Applied to aeronautical configurations, the resonance frequency decreases considerably compared to a conventional resonator (factor of about 1/5) but with a reduction of the maximum absorption when the tubes fill the cavity. Experiments in impedance tube validate the theoretical approach.
Volumetric resistance blower
Authors: MacDonald Mark , Heymann Douglas
Published: May 2013

This paper reports on a new low-noise blower rotor technology developed by Intel Corporation (patents pending). The new approach replaces the traditional centrifugal blower rotor with a block of continuous porous media. The porous media can be as simple as a low-cost, block of open-cell foam and has no blades or macroscale structure. As the porous media rotor rotates, viscous and inertial forces from the volumetric resistance of the porous media cause the air within the rotor to rotate with it, creating centrifugal forces that overwhelm the flow resistance in the radial direction and create a flow pattern similar to that achieved in a traditional blower. However, because of the lack of distinct blades, the porous-media generates nearly zero aerodynamic tonal noise and significantly reduced broadband noise. This allows the rotor to be operated at significantly higher RPM and reduced clearances relative to the traditional rotor design for further improved performance. This paper will discuss numerical modeling and experimental development of the new blower type. An iso-flow comparison of porous-media and traditional rotors with the same motor and housing demonstrate a 5 dBA reduction in broadband noise and a factor of two reduction in tonality while maintaining comparable overall efficiency. Impact of porosity and different rotor support structures are also discussed.
Numerical investigation of acoustically excited flow through an orifice using lattice Boltzmann method
Authors: Ji Chenzhen , Zhao Dan
Published: May 2013

Two-dimensional time-domain numerical investigation of sound-induced flow through an orifice with a diameter 6 mm is conducted by using lattice Boltzmann method. Emphasis is placed on characterizing its acoustic damping behaviors. The main damping mechanism is identified as incident waves interact with the shear layers formed at the orifices rims and the acoustic oscillations destabilize the shear layers to form vortex rings. And acoustic energy is converted into vortical energy. To quantify the orifice damping effect, power absorption coefficient is used. It is related to Rayleigh conductivity and describes the fraction of incident acoustical energy being absorbed. Numerical simulations are conducted in time domain by forcing a fluctuating flow with multiple tones through the orifice. This is different from frequency-domain simulations, of which the damping is characterized one frequency at a time. Comparing our results with those from Howe’s theoretical model, good agreement is observed. In addition, orifice thickness effect on its damping is discussed.
Scattering of sound waves at an area expansion in a cylindrical flow duct
Authors: Boij Susann , Yanac Cinar Özge , Cinar Gökhan , Nilsson Börje
Published: May 2013

Sound propagation in pipes and ducts with flow, like ventilation ducts and exhaust pipes, is influenced by flow separation and vortex production at sharp edges along the ducts, such as at bends and area expansions. Shear layers form at the separation points, and such layers are unstable to low frequency acoustic disturbances. An analytical model, aiming at physical insight into this interaction, is presented. Results in the plane wave region for the so called scattering matrix for a sudden area expansion with flow in cylindrical pipes are compared with experimental values. Both the magnitude and the phase, in the form of an end correction, is presented. The model is also compared to a 2 dimensional model, in order to evaluate the anticipated increased accuracy of the 3 dimensional modeling. The scattering coefficients are strongly dependent on the flow speed, which is up to a Mach number of 0.5. It is observed that for low frequencies, the interaction is dominated by the dynamics of an unstable shear layer downstream of the edges. For higher frequencies, the wave propagation is mainly affected by convective effects. Differences in properties for the 2D and the 3D cases are also explored.
Design of a built-in electroacoustic resonator for active noise reduction
Authors: Boulandet Romain , Rivet Etienne , Lissek Hervé
Published: May 2013

The paper focuses on the design of a built-in electroacoustic resonator for active noise reduction purposes. This concept basically encompasses a loudspeaker connected to a synthetic electrical load that enhances the ability of the transducer to dissipate a certain part of the incoming acoustic energy. The strategy is therefore to control the dynamics of boundaries in closed sound spaces (such as room, cavity, etc.) rather than targeting a global control that requires significant input of additional acoustic energy. The main attraction of the proposed methodology is its ability to achieve broadband sound absorption while bypassing the use of sensors, the sensing of sound field information being incorporated within the synthetic electrical load admittance (current/voltage transfer function). Computational and experimental results are provided to illustrate the benefits and potential of a built-in electroacoustic resonator compared to other options. Concluding remarks and discussions on foreseen future developments are then provided.
Ultra-low frequency underwater acoustic projectors: Present status and future trends
Authors: Dubus Bertrand , Mosbah Pascal , Hartmann Jean-Rémi , Garcin Jacky
Published: May 2013

Ultra-low frequency (ULF) underwater transducers, used in the 10–400 Hz frequency range, have usually radiating surfaces the dimensions of which are small with respect to the acoustic wavelength. To radiate a high acoustic power with a monopolar ULF transducer, a large volume velocity is required to counterbalance the low radiation resistance. Three transduction technologies are available to realize compact high power ULF transducers: hydroacoustic, electromagnetic, and active material-based. In the latter case, piezoelectric ceramics and magnetostrictive rare-earth alloys are often associated to flexural vibration such as found in flextensional transducers. Compared to these materials, piezoelectric single crystals, which exhibit lower stiffnesses and produce higher strains together with higher energy densities, are potential active materials for future ULF underwater transducers. In this work, ULF transducers are analyzed in terms of their working frequencies, acoustic powers, and masses. Thirty-two ULF underwater projectors build during the last 25 years are considered. For single crystal transducers, prototypes working at higher frequencies as well as transducers modeled with finite element method are taken into account. Using these data and classical scaling laws, abacuses displaying acoustic power-frequency curves for given masses are constructed for each technology. They show that single crystals transducers could provide more compact and powerful solutions for frequencies above 40 Hz.
Electroacoustic metamaterials: Achieving negative acoustic properties with shunt loudspeakers
Authors: Lissek Herve
Published: May 2013

Acoustic metamaterials constitute a new class of structures that exhibit acoustic properties not readily available in nature. These properties can be a negative mass density, expressing the opposition of the acceleration of a particle to the application of pressure, or a negative bulk modulus, signifying the rarefaction of the particle in reaction to a compression (resp. a condensation in reaction to a depression). However, these artificial behaviors result from a periodic arrangement of passive unit-cells (such as membranes and side holes), and not from individual “meta-properties” of each unit-cell. It is however possible to observe such intrinsic metamaterial properties out of a passive electroacoustic resonator. This concept encompasses a loudspeaker, connected to a specific electric load, thus altering the acoustic dynamics of the loudspeaker diaphragm when subject to an exogenous sound source. It is especially possible to achieve negative acoustic impedance at its diaphragm, thanks to the connection of passive electric shunt circuits, such as simple RLC series resonators. This paper aims at highlighting the metamaterial nature of such electroacoustic resonators through computational and experimental results, followed by discussions on ongoing developments.
Loudspeaker for low frequency signal driven by four piezoelectric ultrasonic motors
Authors: Ohga Juro , Negishi Hirokazu , Oohira Ikuo , Saito Hiroya , Oishi Kunio , Maeda Kazuaki
Published: May 2013

The authors are developing a completely new direct-radiator loudspeaker as an alternative of the conventional electrodynamic loudspeaker. It is driven by continuous revolution of piezoelectric ultrasonic motors, It is useful for radiation of very low frequency signal because it shows almost flat phase frequency characteristics in low frequency region. A preliminary model, named dual-motor, de-spin (DMDS) model, included co-axial two ultrasonic motors. Stator of one motor is fixed to the base and of the other is connected to the cone radiator. Velocity modulation for any motor induces driving force for the cone radiator. Output sound at low frequency range (for example, 30–120 Hz) by this model was excellent because it has no significant resonance in this frequency region. However, its operation was occasionally instable. At this Congress, a highly improved model named quad-motor, de-spin (QMDS) model is presented. It uses two co-axial DMDS mechanisms. The experimental model has a cone radiator of 46 cm in diameter and an enclosure of 400 L. Its working frequency range is same as DMDS model. Harmonic distortions included in the output signal are improved to be less than 10%. Its sound quality is excellent.
The design of ultrasonic lead magnesium niobate-lead titanate composite transducers for power and signal delivery to implanted hearing aids
Authors: Leadbetter Jeff , Brown Jeremy , Adamson Rob
Published: May 2013

We present a system for efficiently powering implanted hearing aids by transmitting an ultrasonic signal across the skin. The use of ultrasound as method for power and signal transfer is known for embedded systems in industrial applications and has more recently been investigated for use with other medical implants. In our application, ultrasonic transducers are investigated as they offer substantially reduced size relative to traditional magnetic induction coil power delivery. The developed transducers use lead magnesium niobate-lead titanate (PMN-PT) piezoelectric material in a 1–3 composite formulation. PMN-PT offers an electromechanical coupling factor (kt, an indicator of maximum efficiency) that is up to 60% greater than traditional piezoceramics, while the use of composite transducers removes geometric constraints that can limit the achieved efficiency. The fabrication methods for the transducers are detailed. Experimental results are presented to show the composite transducers achieve a kt of 0.86 (out of 1.00), and a power transmission efficiency that is improved by 38% relative to a similar non-composite transducers. It is also demonstrated that these transducers offer sufficient bandwidth for amplitude or frequency modulation schemes to transmit data signals along the power carrier beam.
Biocompatible wireless power transferring and charging based on ultrasonic resonance devices
Authors: Lee Sung Q , Youm Woosub , Hwang Gunn
Published: May 2013

To increase application area of implantable devices for medical treatment including implantable cardiac defibrillator or deep brain stimulator, the rechargeable battery module is highly requested. The previous Li-type battery has limited current sources, so that the patient is forced to have surgery just for changing battery. Previous technologies such as magnetic resonance and induction coupling have limited applications because of its short transfer distance compared to device size and magnetic field intensity limitation for the safety of body exposure. As an alternative, the biocompatible wireless power transferring and charging technology is proposed using ultrasonic resonance devices. For the high efficient power transferring, optimal transfer frequency is calculated based on the acoustic radiation and damping effect. Then, the optimal load resistance is selected for matching power condition in receiver. And, transmitter is designed to match the optimal transfer frequency. The ultrasonic resonance transmitter and receiver are manufactured with the size of 20 mm diameter, 6.0 mm height. The energy conversion efficiency from input electrical power of transmitter and output power of receiver is about 25.6% at 10 cm distance, experimentally. The maximum transferring power is up to 15 mW. This result is quite high considered with the device size and the power transfer distance.
A morphological and acoustic study on the effect of a trumpet player's vocal tract
Authors: Kaburagi Tokihiko , Yamada Naoyuki , Fukui Takashi , Minamiya Eriko
Published: May 2013

A morphological and acoustic study is presented to examine the role of the vocal tract in playing the trumpet. Preliminary results obtained from one professional player are shown, and the effectiveness of the method is demonstrated. Images of the vocal tract with a resolution of 0.5 mm (2 mm in thickness) were recorded with magnetic resonance imaging to observe tongue posture and to estimate the vocal-tract area function during actual trumpet performance. The input impedance was then calculated for the player's air column, including both the supra- and sub-glottal tracts, using an acoustic tube model that also considers wall losses. Finally, a time-domain blowing simulation was performed with a lip vibration model (Adachi and Sato, J. Acoust. Soc. Am. 99, 1200–1209, 1996). In this simulation, the oscillating frequency of the lips was slightly affected by using different shapes of the vocal tract measured for the player. In particular, when the natural frequency of the lips was gradually increased, the transition to higher modes occurred at different frequencies for different vocal-tract shapes. Furthermore, simulation results showed that the minimum blowing pressure required to attain lip oscillation can be reduced by properly adjusting the vocal-tract shape.
Simulating different upstream coupling conditions on an artificial trombone player system using an active sound control approach
Authors: Fréour Vincent , Hélie Thomas , Lopes Nicolas , Caussé René , Scavone Gary P.
Published: May 2013

Recent research suggests that the ability to finely tune vocal-tract resonances during trombone playing may constitute an important aspect of performance expertise. Artificial player systems, designed to reproduce the behavior of a real player, often neglect this component by not providing any control of upstream resonances. However, they offer great experimental platforms for quantitative studies on sound production mechanisms, allowing independent adjustment of certain control parameters. An active sound control method was designed to improve high tone support and investigate different conditions of coupling between the artificial lips, the downstream air-column, and the upstream cavity during sustained tones played by an artificial valve-trombone player system. Upstream input impedance at the fundamental frequency was controlled through real-time adjustment of the phase and amplitude ratio between the acoustic pressure generated on both sides of the lips. The phase difference between the upstream and downstream pressures was swept linearly while maintaining different conditions of upstream energy and fixed trombone fingering. Observations during this procedure included: (1) significant fundamental frequency variations in the neighborhood of a downstream impedance peak; and (2) variation of the downstream energy and optimal phase tuning with regard to the mechanical efficiency of the lip-valve system suggested at the energy maximum.
Analysis of bow-change strategies
Authors: Guettler Knut
Published: May 2013

One of the most important skills of the accomplished bowed-string player is the smooth bow change. Smooth changes are often necessary in order to keep a phrase flowing, and equally important in situations where the bow is too short for the duration of the given note, the latter requiring a bow change of least possible audibility. The problem arises from the fact that a change of bowing direction requires the rotation of the Helmholtz corner to be reversed, and the phases of the string-velocity frequency components thus to be shifted 180̊. In between the two states, there exists no transition that can fully maintain the sound flow without introducing undesirable noises. However, by choosing the right bowing strategy and gesture, the tradeoff between transition time and noise content can be optimized for the purpose. In practice, different players solve this problem in a number of ways. The present study, which is mainly based on numeric simulations, analyzes the sounding outcome of a variety of possible bowing parameters.
Improving speech intelligibility in active hearing protectors and communication headsets with subband processing
Authors: Brammer Anthony J. , Yu Gongqiang , Bernstein Eric R. , Cherniack Martin G. , Peterson Donald R.
Published: May 2013

Parallel subband processing, in which the full bandwidth of environmental noise and a communication channel are processed separately in contiguous, restricted frequency bands, has been proposed as a means to improve speech intelligibility in noise for active hearing protectors and communication headsets (Bernstein et al., Int. J. Ind. Ergonom., in press). An active, adaptive feed-forward control structure has been employed to improve the audibility of sounds in the communication channel of a circumaural hearing protector / headset while active noise reduction (ANR) is used to complement the passive attenuation of the device from 50 to 800 Hz. The communication channel subbands have been implemented as octave bands from 125 Hz to 8 kHz. The performance of the device has been evaluated in a diffuse field when worn by human subjects. Word intelligibility in industrial noise was evaluated when the active system was not operating, when the device was operating as a fullband ANR system with fixed communication channel gain, and as a subband ANR system with adaptive gain of the communication channel signal to improve the speech signal-to-noise ratio. A significant improvement in speech intelligibility can be obtained with the subband system. [Work supported by NIOSH 5R01OH 008669.]
A case-study on the continuous use of an in-ear dosimetric device
Authors: Mazur Kuba , Voix Jeremie
Published: May 2013

In order to further understand the combined effects of occupational and recreational noise exposure with regards to noise induced hearing loss (NIHL), an in-ear dosimeter prototype meant for continuous use was developed. The device acts as a hearing protection device (HPD) and can measure and log effective in-ear sound pressure level as well as unprotected levels. To enable its continuous use, this HPD is also equipped with a bypass feature for “transparent” hearing, input for music or communication devices and interfaces with Android smartphones. The proposed device allows for the implementation of an algorithm accounting for the auditory fatigue recovery rate, providing a true representation of the current accumulated noise dose. This allows for 24 h dosimetry and avoids having the user manually reset the dose back to 0% on the next day and thus assuming complete fatigue recovery has occurred. This paper details the proposed recovery algorithm, presents collected field data, and discusses the benefits as well as real-world challenges of using such a device.
Estimation of noise exposure level for subjects wearing hearing protector devices
Authors: Le Cocq Cécile , Nélisse Hugues , Boutin Jérôme , Voix Jérémie , Laville Frédéric
Published: May 2013

Industrial workers are exposed to noise levels that could damage their hearing. The Field-MIRE (F-MIRE) method has been developed to quantify earplug and earmuff attenuations with two microphones located under and outside of the HPD. This technique has been designed to be used in the field, but does not give a direct access to the noise exposure level, that is, the noise level at the head location without the subject. In this article, we present a combination of the F-MIRE method with a proposed technique to estimate the sound pressure level without subject, in order to quantify both the ambient and protected noise exposure levels and deduce the effects on worker hearing. Several experiments have been conducted on four subjects with three types of earplugs and with five types of earmuffs. First, the best location for the microphone outside of the HPD has been determined. Second, correction factors that need to be applied on the outside microphone measurement to estimate the sound pressure level without subject have been quantified. Finally, the proposed technique has been validated with measurements taken in a simulated workplace.
Use of passive hearing protectors and adaptive noise reduction for field recording of otoacoustic emissions in industrial noise
Authors: Nadon Vincent , Bockstael Annelies , Keppler Hannah , Botteldooren Dick , Lina Jean-Marc , Voix Jérémie
Published: May 2013

Distortion product otoacoustic emissions (DPOAEs) can detect noise-induced hearing loss in-field, but their data extraction is very sensitive to background noise. This paper investigates how passive and active noise reduction enhance DPOAE recording based on data collected in white noise from 54 dB(A) to 90 dB(A). Despite considerable high-frequency attenuation from a proper placed DPOAE probe, 54 dB(A) background noise deteriorates the test outcome substantially. More low-frequency attenuation by an extra passive earmuff enables measurements in white noise levels of 70 dB(A). The relationship between external sound level and noise recorded by the DPOAE system has been statistically modeled. Additionally, the upper limits of attenuation improvement are analyzed by quantifying residual physiological noise. Furthermore, for an earplug integrating microphone and speakers of the DPOAE measurement probe, adaptive noise reduction processing on the DPOAE signal is used to improve the signal-to-noise ratio. The adaptive noise reduction (ANR) is implemented using the NLMS algorithm to filter out the ambient noise, measured by the first microphone measuring the DPOAE signal, with a second miniature microphone mounted flush with the external faceplate of the isolating DPOAE probe. Simulated data show that DPOAE response extraction is possible in an environment with noise levels exceeding 70 dB(A).
Proposed standard—Guidance for developing state noise regulations and local noise ordinances
Authors: Brooks Bennett M.
Published: May 2013

The American National Standards Institute (ANSI) Accredited Standards Committee S12 (Noise) Working Group (WG) 41 has been developing a draft standards document for over 12 years. The current document is in Draft #9, now under development. This document represents the consensus of many stakeholders in the community noise arena, including industry, government, consulting, and the public. The purpose of the document is to provide guidance to government officials, acoustical consultants, and other interested persons on how to develop a community noise ordinance or regulation, which is appropriate for the existing local circumstances. The document addresses issues such as public and government priorities and values, and available resources, and also provides the technical basis to manage the local sound environment. The keys to the effectiveness of the document are that it provides a menu of options for the user, discusses the trade-offs involved for decisions that must be made by government officials, and emphasizes that enforcement of a community noise ordinance is crucial to its success. A description of the current draft is presented.
New athletic fields for Saint Joseph's University: A community noise battle
Authors: Doggett Felicia
Published: May 2013

Saint Joseph's University, located in Philadelphia, purchased a vacated private school campus adjacent to theirs. This new campus, which resided in neighboring Lower Merion Township, included 15 acres of open fields that the university desired to turn into NCAA (National Collegiate Athletic Association) baseball, softball, and field hockey fields. Proposed improvements to the fields included permanent bleacher seating, press boxes, dugouts, batting cages, artificial turf playing surfaces, re-grading of the fields, and sound reinforcement systems among other changes. The surrounding community vehemently opposed the proposed changes largely due to the potential noise generated from cheering crowds and sound systems. Through a year and a half of township hearings with testimony provided by a plethora of expert witnesses, Saint Joseph's University finally received approval with various restrictions to build their fields. This presentation explores the research, measurements, and modeling methods undertaken to quantify the acoustical implications on the surrounding community.
The roles of acoustic cavitations in the ultrasonic cleansing of fouled micro-membranes
Authors: Yang Yuanxiang , Wang Qianxi , Tan Soon Keat
Published: May 2013

This paper concerned the experimental studies on the cleansing mechanism of acoustic cavitation bubbles near the fouled micro-membranes. The existence of the membrane created asymmetry in the flow field, which forced the cavitation bubble to oscillate non-spherically and finally brought forth the jet impact. The oscillations and micro-jets of the cavitation bubbles enhanced the dynamic features of the fluid nearfield and improved the capability of removing fouling. The study on the acoustic multi-bubble system was quite complicated, so first, we focused on the individual bubble dynamics near the membrane. A succession of individual cavitation bubbles were created by Q-switched Nd: YAG laser pulses and observed using a high-speed camera (up to 100 000 frames per second). The jet flow hit against the membrane surface with velocity above 100 m/s, which was strong enough to remove the adherent fouling. We compared the cleansing effects of the cavitation bubbles with different laser energies and stand-off distances from the membrane surface. And then based on the individual bubble dynamics, we can deduce the influence of cavitations in the ultrasonic cleansing of micro-membranes.
Acoustic deformation of cells
Authors: Mishra Puja , Hill Martyn , Glynne-Jones Peter
Published: May 2013

The stretching of cells using optical tweezers has been previously demonstrated, enabling the mechanical properties of individual cells to be assessed with potential applications in, for example, identifying cancer cells and parasite infections such as malaria. We demonstrate here a system that uses acoustic radiation forces to compress levitated cells to an extent comparable to that demonstrated with optical tweezers. While the deformation of levitated droplets has been demonstrated in the past, this paper addresses the challenge of producing significant forces on objects that have low acoustic contrast with their host medium and are small compared to the acoustic wavelength. The acoustic deformation can potentially be applied to many (e.g., thousands) of cells simultaneously, opening the way to higher throughput diagnostic devices. In our system, osmotically swollen red blood cells (RBCs) are used to demonstrate the principle as they are particularly compliant due to the absence of a cytoskeleton. A resonance is formed in a square capillary of inner dimension, 100 µm. Excited by a transducer at a half-wave resonance of 7.9 MHz, cells are both levitated and focused laterally into a single line down the center of the capillary prior to the compression forces being applied. We present finite element models of the acoustic deformation, verifying our code against known results for droplet deformation.
Application of acoustic radiation pressure to align cells in a commercial flow cytometer
Authors: Kaduchak Gregory , Ward Michael D.
Published: May 2013

Forces derived from acoustic radiation pressure can be used to replace or partly replace hydrodynamic forces to align cells and particles in flow cytometry. The ability to focus cells into a tight line without relying on hydrodynamic forces allows many new possibilities for sample delivery. Dilute samples can be processed quickly. Flow velocities can be varied allowing control of particle delivery parameters such as laser interrogation time and volumetric sample input rates. Recently, a commercial flow cytometer that directs particles into the laser interrogation region using acoustic radiation pressure in a 200 μm channel has been developed. In this talk, the application of acoustic radiation pressure in flow cytometry systems from fundamental principles to implementation details will be presented. Data will be shown for both the operational implementation of the acoustic focusing device as well as demonstrating its ability to perform for complex biological assays.
Acoustic radiation force to reposition kidney stones
Authors: Bailey Michael , Wang Yak-Nam , Simon Julianna C. , Cunitz Bryan W. , Harper Jonathan D. , Hsi Ryan S. , Starr Frank , Paun Marla , Dunmire Barbrina , Sapozhnikov Oleg A. , Crum Lawrence A. , Sorensen Mathew D.
Published: May 2013

Our group has introduced transcutaneous ultrasound to move kidney stones in order to expel small stones or relocate an obstructing stone to a nonobstructing location. Human stones and metalized beads (2–8 mm) were implanted ureteroscopically in kidneys of eight domestic swine. Ultrasonic propulsion was performed using a diagnostic imaging transducer and a Verasonics ultrasound platform. Stone propulsion was visualized using fluoroscopy, ultrasound, and the ureteroscope. Successful stone movement was defined as relocating a stone to the renal pelvis, ureteropelvic junction (UPJ), or proximal ureter. Three blinded experts evaluated for histologic injury in control and treatment arms. All stones were moved. 65% (17/26) of stones/beads were moved the entire distance to the renal pelvis (3), UPJ (2), or ureter (12). Average successful procedure per stone required 14±8 min and 23±16 pushes. Each push averaged 0.9 s in duration. Mean interval between pushes was 41±13 s. No gross or histologic kidney damage was identified in six kidneys from exposure to 20 1-s pushes spaced by 33 s. Ultrasonic propulsion is effective with most stones being relocated to the renal pelvis, UPJ, or ureter. The procedure appears safe without evidence of injury. [Work supported by NIH DK43881, DK092197, and NSBRI through NASA NCC 9-58.]
Acoustophoretic force-based compressibility measurement of cancer cells having different metastatic potential
Authors: Wang Han , Liu Zhongzheng , Shin Dong Moon , Chen Georgia , Cho Younghak , Kim Yong-Joe , Han Arum
Published: May 2013

Mechanical properties of cells such as compressibility are regarded to be different as cancer cells progress into metastatic state. Traditional methods for measuring mechanical properties of single cells such as AFM and micropipette aspiration require labor-intensive procedures and can cause damage to cells due to direct contact, thus unsuitable for high-throughput measurement. Acoustophoretic force exerted on particles under acoustic-standing-waves depends on the particle and medium’s vibro-acoustic properties. Thus, cells with different mechanical properties show different mobility under acoustic resonant field, which can be analyzed to decipher the mechanical properties of cells. Here we present a high-throughput, single-cell-resolution, cell compressibility measurement approach based on acoustic-standing-wave-induced force, and the finding that head and neck cancer cells having different metastatic capacities show noticeable differences in compressibility. The acoustophoresis chip has a straight flow channel with a piezoelectric transducer attached at the bottom. Trajectories of moving cells in the channel under acoustic standing wave excitation in the absence of flow are recorded. By using a microfluidic acoustophoretic model, the simulated trajectories of cells are calculated. The mechanical properties of cells are estimated by fitting the experimental and simulated trajectories thereby. Cells with highest metastatic capacity showed highest compressibility, consistent with previously reported clinical observations.
Applications of models of binaural hearing
Authors: Blauert Jens P. , Braasch Jonas
Published: May 2013

Models of binaural hearing have been proposed for more than 60 decades, but it is only recently that they are ready for technological application. Recognizing this situation, 15 laboratories in Europe and in the United States have founded a research group (AABBA) with the aim of setting in place “Aural Assessment by Means of Binaural Algorithm.” Now, after its first 4-years term of activity, the group has published their recent results in a chapter book (Springer)—including a software package for building customized binaural models. In this talk, the group’s most relevant results will be described. The results concern the following areas of model application, among others: binaural analysis of aural scenes, binaural de-reverberation, binaural quality assessment of audio channels, loudspeakers and performance spaces, binaural perceptual coding, binaural processing in hearing aids and cochlea implants, binaural systems in robots, binaural/tactile human–machine interfaces, speech-intelligibility prediction in rooms, and/or multi-speaker scenarios. Current members of AABBA are research labs at Universities/Techn. Universities in Helsinki, Boston, Cardiff, Oldenburg, Lyon, Troy, NY (Rensselaer), Bochum, Berlin, Copenhagen, Dresden, Eindhoven, Munich, Paris (Pierre et Marie Curie), Toulouse, and at the Austrian Academy’s Acoustics Research Inst. in Vienna.
Statistical analysis of head related transfer function data
Authors: Luo Yuancheng , Zotkin Dmitry N. , Duraiswami Ramani
Published: May 2013

The head related transfer function (HRTF) is a function that characterizes the response of a given individual to sound from a particular location in an egocentric coordinate system. The range dependence is often neglected, and the HRTF is approximated as a function of frequency and direction, H(θ,φ,ω). The HRTF displays considerable inter-personal variability, and a major open problem is the development of a generative model for the HRTF from anthropometry. Further, the sampling used in measuring HRTF data varies widely from database to database, and moreover often there are no measurements for elevations below the subject. This raises associated questions of optimal sampling, interpolation, hole-filling, and others. In this work, we model the HRTF via a non-parametric, data-driven, Gaussian Process Regression model. We develop efficient regression techniques to perform inference using this model on measured HRTF data. We then suggest methods for HRTF interpolation, HRTF extrapolation, feature extraction, sampling, and personalization. The methods are tested on the CIPIC database and results presented. [Partial NSF support is gratefully acknowledged.]
A three dimensional children head database for acoustical research and development
Authors: Harder Stine , Paulsen Rasmus R. , Larsen Martin , Laugesen So/ren
Published: May 2013

Most computational–acoustic work within spatial hearing relies on head-related transfer functions from databases of measurements taken on adult humans or dummy heads. We aim to provide a set of 3D digital heads including children, from which head-related transfer functions can be computed instead of measured. However, current volumetric scanning techniques do not have sufficient resolution for accurately scanning the external ear, and computed tomography also involves radiation. In this paper, we propose a framework for scanning, stitching, and meshing complete human heads. The process starts by acquisition of multiple 3D surface scans of the same subject using a high-resolution photogrammetric scanner. Second, the scans are semi-automatically aligned and noise and incoherence is removed. This is followed by an iterative process where a volumetric implicit representation of the head is optimized. The process consists of a regularized surface-reconstruction step followed by an alignment step. Finally, a surface representation of the entire head is extracted using a triangulation of the zero-level iso-surface of the implicit volume. The process has been used to reconstruct the heads of children aged 10 months to 9 years. The data and the associated reconstruction algorithms will be made publicly available for use in acoustical research and development.
Consistency among the head-related transfer functions from different measurements
Authors: Zhong Xiao-li , Xie Bo-sun
Published: May 2013

Empirical measurement is a common approach to obtaining head-related transfer functions (HRTFs). Due to differences in experimental conditions and possible errors, some deviations exist among the data from different measurements even for the same subject. This work aims to evaluate deviations of HRTFs from different measurements. Five sets of KEMAR HRTFs from three groups including MIT-media Lab, CIPIC Interface Lab, and our lab are used. A free-field equalization is applied to the original data so as to eliminate the influence caused by the difference in the response of electro-acoustic measuring chain. The deviations among HRTF magnitudes for different measurements are specified by spectral distortion. Results indicate that the magnitude deviation increases with increasing frequency and reaches more than 10 dB above the frequency of 6 kHz. Salient deviations often occur in contralateral source directions or in ipsilateral source directions near the frequency of pinna-related notch. Nevertheless, most deviations can be effectively reduced after an auditory filter smoothing. This work suggests that the inconsistency in measured HRTF data and its impact on auditory perception should be taken into account when comparing and standardizing HRTFs from different measurements. [Work supported by National Nature Science Fund of China Grant No. 11004064]