bluuebunny/crossref_metadata_2025 huggingface dataset:
Transduction as energy conversion: Harvesting of acoustic energy in hydraulic systems
Authors: Skow Ellen A. , Cunefare Kenneth , Erturk Alper
Published: May 2013

Energy harvesting from acoustic energy sources is a form of transduction. While energy densities in typical airborne acoustic noise fields are extremely low, those in hydraulic systems may be orders of magnitude greater and represent an opportunity for direct energy conversion from piezoelectric materials for powering sensor and communication nodes. Hydraulic systems are challenging from a design perspective in that the device must be capable of withstanding static pressures up to and exceeding 35 MPa, while being simultaneously exposed to dynamic pressures on the order of 3.5 MPa. Hydraulic pressure energy harvester devices have been developed to exploit the high energy densities of dynamic pressures in hydraulic systems. There is an immediate application for this technology in that state-of-the-art hydraulic hose and piping systems employ integral sensor nodes for structural health monitoring for early detection of incipient failures. This paper presents the acoustic and electromechanical modeling of the piezoelectric power output from dynamic pressure in terms of the force transmitted into an energy harvester designed for hydraulic systems.
Human echolocation system using a miniature dummy head
Authors: Uchibori Shunsuke , Kinoshita Masataka , Ashihara Kaoru , Ohta Tetsuo , Hiryu Shizuko
Published: May 2013

To promote understanding of sonar mechanisms in bats, we propose a novel tool that makes echolocation available for humans. In this method, ultrasonic echoes are captured by a miniature dummy head so that they can be converted to binaural audible sounds using time expansion.In order to examine the effectiveness of this technique, perceptual listening tests were conducted on human listeners with normal hearing.The sounds (white noise with frequencies between 5 and 90 kHz with 0.7-s duration, including 0.05-s rise/fall time) were recorded at a distance of 1 m from a loudspeaker using two condenser microphones that were placed in the ear canals of a 1/7 size miniature dummy head. The recorded ultrasounds were 1/7-times pitch converted, and then were presented to the listener through headphones. As a result, the listeners perceived correct directions of the pitch converted sounds, which were recorded using the miniature dummy head, although front-back error was occasionally observed. When the miniature dummy head was rotated during the recording, the listeners perceived the movement of the sounds as out-of-head sound localization. The miniature dummy head may provide humans with a tool to understand biosonar mechanisms.
Capturing spatial audio information by using a miniature head simulator
Authors: Taki Kousuke , Ashihara Kaoru , Kiryu Shogo
Published: May 2013

A conventional dummy head or a microphone array with a number of microphones has been used to record spatial audio information. We propose an audio capture system called “Miniature head simulator” that consists of a microphone system and a signal processor. Instead of using a conventional dummy head, a small microphone system that consists of three omni-directional microphones is used to capture acoustic signals. The signals are then encoded to a custom data format and transmitted online. The transmitted data can be decoded and reproduced as binaural signals. Because of its size and weight, the conventional dummy head has been used exclusively for the research purpose. A miniature head simulator can provide much more convenient tools to record spatial audio information. Since it deals with only three channels of audio stream, data can be processed with relatively low computational cost. By using a miniature head simulator, spatial audio information can be streamed to the browser or even to the smartphones of the end-users. It can be used in a remote acoustic sensor and remote control system, sound detection system, video conference, and various other fields of industry.
Criteria for wind-turbine noise immissions
Authors: Hessler George , Schomer Paul
Published: May 2013

Each of the two authors has developed recommended single, 24-h, constant wind turbine noise criterion; the criteria are constants because wind turbine noise is basically not adjustable. Hessler develops his criterion from his knowledge of how wind turbine noise is being regulated at the local, state, and national levels, from regulations in other countries, and from his extensive experience with numerous wind turbine projects. Schomer develops his recommended criterion on the basis of existing national and international standards; notably ISO 1996-Part 1 and ANSI/ASA S12.9 parts 4 and 5. Ultimately, Hessler comes up with a single, 24-h A-weighted average criterion of 40 dB, and Schomer comes up with a 24-h A-weighted average criterion of 39 dB. These two researchers have decidedly different backgrounds, different experience, and a slight difference in orientation towards the industry. Thus, it is remarkable that these two criteria, derived in such different ways result in nearly identical 24-h A-weighted criteria levels. Although there is essential agreement in immissions criterion, there are variables debated herein for both modeling wind turbine emissions and certifying such emissions at far-off receptors that could result in a 10 dBA difference in the actual immissions level.
A multi-objective evolutionary optimization approach to procedural flight-noise mitigation
Authors: Christian Andrew , Sparrow Victor
Published: May 2013

Exposure to noise is a significant problem for communities that exist near airports. The distribution of noise exposure can be positively affected by changes in the procedures that aircraft follow in the vicinity of an airport (e.g., rate of ascent, ground track, etc.). When considering such changes, a decision maker often has to weigh the objective of lower noise impact against “more practical” considerations such as fuel consumption and time-of-flight. This study presents a method of numerical optimization which seeks to find the optimal-tradeoff set (Pareto front) of flight procedures given information about an airport and the surrounding population and geography. This front will only include procedures such that an aggregate noise metric cannot be improved without detriment to a more practical objective. A contemporary multi-objective evolutionary algorithm is used as the basis of the optimization effort. Results from a simulated military airfield near Asheville, NC are shown. Ways in which decision makers are empowered by having access to a Pareto front are discussed.
Evaluation on fracturing effects in a low-permeability reservoir using acoustic logging data
Authors: Baohua Huang m. , Hao Chen , Jianqiang Han , Xiao He
Published: May 2013

Low-permeability reservoirs are frequently discovered in worldwide petroleum exploration. More than 50% of oil and gas reservoirs are of low permeability. Formation fracturing technique is the most common way to develop oil production in this type of reservoirs. The fracturing effect, however, is hard to be evaluated in practice. And thus arguments always exist between constructors and geologists. We developed a favorable method to evaluate the effect from the reservoir anisotropy analysis results provided by cross dipole logging technique. The data will be measured in an open hole or a borehole when formation is before and after fractured, respectively. The formation anisotropy can be estimated from the logging data. The fracturing effects can thus be evaluated by comparing the results of perforation intervals. Small differences of anisotropy estimation results indicate failure fracturing; while good fracturing effect can be confirmed if the anisotropy of a fracturing reservoir is stronger than before. Fracturing intervals can also be predicted by the anisotropy curves of a fracturing reservoir as well as the new oil production. This approach has been applied for the evaluation of deep tight reservoirs in Daqing Oilfield and low-permeability reservoirs in Hailar. Efficient evaluation results have been obtained, which provided useful information to geologists for further explorations.
Simulation study on seismic monitoring of aquifers
Authors: Lähivaara Timo , Kaipio Jari P. , Dudley Ward Nicholas F. , Huttunen Tomi
Published: May 2013

This study focuses on developing computational tools to estimate groundwater volume from seismic measurements. The poroelastic signature from an aquifer is simulated and methods to use this signature to estimate porous properties of the permeable rock and the level of the water table are investigated. In this work, the spectral-element method (SEM) is used for solving the forward model that characterizes propagation of seismic waves. The SEM combines the accuracy of the global pseudospectral method with the flexibility of the classical finite element method. The SPECFEM-2D software is used for calculating seismic wave fields (forward + adjoint) in elastic and poroelastic media. The inverse problem is solved in the Bayesian framework, which makes efficient use of a priori information related to modeling and measurement uncertainties of the problem. It this study, preliminary results in the two-dimensional case with simulated data are presented.
Human otoacoustic emissions generated by active outer hair cells
Authors: Frosch Reinhart
Published: May 2013

In the present study, human otoacoustic emissions (OAEs) documented in the literature are shown to agree with predictions based on the hypothesis that the main OAE sources are active cochlear outer hair cells (OHCs) of three different functional categories, namely (1) OHCs enabled by oscillating internal organ-of-Corti resonators (IOCRs) to feed mechanical energy into forward-traveling cochlear waves generated by the acoustic stimuli used, (2) OHCs driving spontaneous localized feedback-generated cochlear-partition vibrations involving standing evanescent sound-pressure waves in the liquids above and below the partition, and (3) OHCs causing nonlinear restoring forces enabling pairs of stationary tones to generate distortion products (DPs). The corresponding predictions of OAE properties are based on cochlear maps, i.e., on certain functions x(f), where f is the frequency of a tone and x is a related distance from the cochlear base, measured along the cochlear channel.
Effects of inner hair cell damage on temporal coding
Authors: Axe David R. , Heinz Michael G.
Published: May 2013

It is widely believed that the neural patterns of temporal coding within the auditory periphery and CNS change following cochlear hearing loss, and a number of recent studies have aimed to more fully understand and characterize these changes. In these studies, noise exposure has been a common method for inducing hearing loss in animal models. Unfortunately, its effects are nonspecific, affecting both inner and outer hair cells as well as the surrounding tissues. Because of this mixed hair-cell damage, it has been difficult to tease apart the specific effects that each of these pathologies has on temporal coding. In the present study, we used the chemotherapy drug carboplatin to induce inner hair cell (IHC) specific lesions in the cochleae of chinchillas. Using acoustically evoked potentials and acute single fiber recordings from the auditory nerve, in parallel with computational modeling, we have investigated the effects of IHC damage on temporal coding. Preliminary findings in carboplatin exposed chinchillas, which show near-normal ABR thresholds, showed a decrease in ABR amplitudes at high sound levels, as well as a decrease in the strength of both envelope and fine-structure coding in frequency following responses. [Research supported by NIH (NIDCD) R01-DC009838 and T32-DC00030.]
The computational prediction of masking thresholds for ecologically valid interference scenarios
Authors: Baykaner Khan , Hummersone Christopher , Mason Russell , Bech So/ren
Published: May 2013

Auditory interference scenarios, where a listener wishes to attend to some target audio while being presented with interfering audio, are prevalent in daily life. The goal of developing an accurate computational model which can predict masking thresholds for such scenarios is still incomplete. While some sophisticated, physiologically inspired, masking prediction models exist, they are rarely tested with ecologically valid programs (such as music and speech). In order to test the accuracy of model predictions human listener data is required. To that end a masking threshold experiment was conducted for a variety of target and interferer programs. The results were analyzed alongside predictions made by the computational auditory signal processing and prediction model described by Jepsen et al. (2008). Masking thresholds were predicted to within 3 dB root mean squared error with the greatest prediction inaccuracies occurring in the presence of speech. These results are comparable to those of the model by Glasberg and Moore (2005) for predicting the audibility of time-varying sounds in the presence of background sounds, which otherwise represent the most accurate predictions of this type in the literature.
Effects of spontaneous otoacoustic emissions on frequency discrimination
Authors: Hansen Rói , Santurette Sébastien , Verhulst Sarah
Published: May 2013

When an external tone is presented in proximity to the frequency of a spontaneous otoacoustic emission (SOAE), the SOAE typically synchronizes to the external tone, a phenomenon known as “entrainment”. As the tone moves further away from the SOAE frequency, beating patterns between the SOAE and the pure tone occur [Long, Hear. Res. 119 (1998)]. This study investigated perceptual consequences of SOAE beating and entrainment on the difference limen for frequency (DLF), which has been found to improve near an SOAE. SOAE entrainment patterns were obtained for six subjects with a strong SOAE in the ipsilateral ear and no SOAE in the corresponding frequency range of the contralateral ear. Hearing thresholds and DLFs were measured ipsi- and contralaterally for nine frequencies covering the entrainment and beating regions of the SOAE. DLFs systematically improved in the entrainment region, worsened when beating occurred, and improved again for frequencies further away from the SOAE. No improvement in DLF was found in any of the contralateral ears tested, suggesting that the effect is of peripheral, rather than of central, origin. The results contradict an earlier hypothesis stating that DLF performance near SOAE frequencies is governed by a central oversensitivity to the SOAE frequency.
Do cochlear mechanisms explain the noise-disruption of the auditory brainstem response to speech?
Authors: Nuttall Helen E. , Heinrich Antje , Moore David R. , de Boer Jessica
Published: May 2013

In background noise, the timing precision of the auditory brainstem response to speech (speech-ABR) is disrupted and the response latency increases. The severity of the disruption has been correlated with listeners’ ability to understand speech-in-noise. To date, although a central mechanism is assumed, the locus of the speech-ABR timing disruption is not clear. The present study aimed to investigate the contribution of different cochlear mechanisms to noise-induced latency increases. A first experiment examined the “cochlear place” mechanism, by which the latency of the response increases as cochlear origin moves towards lower frequency regions. The results showed that the speech-ABR reflects an average over responses from a broad range of cochlear regions, which respond with substantial relative delays. This implies that cochlear place can potentially have large effects on masked speech-ABR latency. Another mechanism that is known to be involved in noise-induced ABR latency increases is neural adaptation. This is presumed to occur at the inner hair cell-nerve junction and is thought to reflect cochlear masking. Thus, if this mechanism contributes to speech-ABR latency increases in noise, we would expect this contribution to depend on cochlear frequency selectivity and amplification gain. This hypothesis is tested in the second experiment.
Sensitivity to stimulus polarity in speech-evoked frequency-following responses
Authors: Aiken Steve J. , Purcell David W.
Published: May 2013

It has been suggested that frequency-following responses recorded to speech sounds presented in opposite polarities can be added to emphasize responses related to the periodicity envelope (e.g., at the fundamental frequency, f0) or subtracted to emphasize responses related to the stimulus fine-structure (e.g., harmonics near formant peaks) because inverting stimulus polarity has little effect on the stimulus envelope. This hypothesis was tested by comparing frequency-following responses to several tokens of two vowels (/a/ and /i/) presented twice in one polarity and once in the opposite polarity, from nine normal-hearing listeners. At harmonics near formant peaks, most listeners displayed frequency-following responses closely related to stimulus fine-structure (i.e., responses that followed stimulus polarity). However, response amplitude and phase at f0 varied greatly across polarities for many listeners, suggesting that the f0 response does not reflect a simple encoding of the periodicity envelope or the fine-structure of the first harmonic. Most listeners had similar responses when identical stimuli were presented in the same polarity, so these varied polarity-sensitive responses were not likely related to temporal encoding difficulties or background electrophysiological noise. The summed alternating polarity frequency-following response at f0 might reflect encoding of both speech fine-structure and the periodicity envelope.
Acoustic supercoupling and enhancement of nonlinearities in density-near-zero metamaterial channels
Authors: Sieck Caleb F. , Fleury Romain , Haberman Michael R. , Alù Andrea
Published: May 2013

Recent theoretical and experimental work has demonstrated that acoustic wave tunneling and energy squeezing can be achieved using density-near-zero (DNZ) metamaterial channels [Fleury et al, J. Acoust. Soc. Am. 132(3), 1956 (2012)]. These channels are directly analogous to supercoupling of electromagnetic waves in near-zero permittivity channels. In optics, the field enhancement and uniformity of response within a near-zero permittivity channel can be employed to produce switching behavior, harmonic generation, and wave mixing even with low amplitude input intensities. These optical channels have been already shown to significantly outperform enhancement of nonlinearity in conventional Fabry-Pérot resonant gratings [Argyropoulos et al., Phys. Rev. B 85, 045129 (2012)]. The analogous properties of velocity field within a DNZ metamaterial channel can result in significant and uniform amplification that may be employed to enhance material or structural nonlinearities in the channel for applications like transmission switches. This work presents recent analytical and finite element modeling of the use of DNZ channels to enhance acoustic nonlinearities. It also explores and discusses metamaterial mechanisms for attaining a tailored and enhanced nonlinear response.
Interactions between listening effort and masker type on the energetic and informational masking of speech stimuli
Authors: Brungart Douglas , Iyer Nandini , Thompson Eric , Simpson Brian D. , Gordon-Salant Sandra , Shurman Jaclyn , Vogel Chelsea , Grant Kenneth W.
Published: May 2013

In most cases, normal-hearing listeners perform better when a target speech signal is masked by a single irrelevant speech masker than they do with a noise masker at an equivalent signal-to-noise ratio (SNR). However, this relative advantage for segregating target speech from a speech masker versus a noise masker may not come without a cost: segregating speech from speech may require the allocation of additional cognitive resources that are not required to segregate speech from noise. The cognitive resources required to extract a target speech signal from different backgrounds can be assessed by varying the complexity of the listening task. Examples include: (1) contrasting the difference between the detection of a speech signal and the correct identification of its contents; (2) contrasting the difference between single-task diotic and dual-task dichotic listening tasks; and (3) contrasting the difference between standard listening tasks and one-back tasks where listeners must keep one response in memory during each stimulus presentation. By examining performance with different kinds of maskers in tasks with different levels of complexity, we can start to determine the impact that the informational and energetic components of masking have on the listening effort required to understand speech in complex environments.
Phase-space equation for wave equations
Authors: Cohen Leon
Published: May 2013

Transforming a space-time function into the phase space of position and wave number offers considerable insight into the nature of the function, and also has many practical applications. If the function is governed by a wave equation then the common procedure is to solve the wave equation and then calculate the phase space distribution function for the solution. We show that significant advantages ensue if one transforms the original differential equation into a phase space differential equation. We give a number of examples and show that phase space equations are often more revealing than the original equation and lead to new approximation methods. [Work supported by ONR.]
Categories, concepts, and calls: Auditory perceptual mechanisms and cognitive abilities across different types of birds
Authors: Hahn Allison H. , Guillette Lauren M. , Hoeschele Marisa , Cook Robert G. , Sturdy Christopher B.
Published: May 2013

Although involving different animals, preparations, and objectives, our laboratories (Sturdy’s and Cook’s) are mutually interested in category perception and concept formation. The Sturdy laboratory has a history of studying perceptual categories in songbirds, while Cook laboratory has a history of studying abstract concept formation in pigeons. Recently, we undertook a suite of collaborative projects to combine our investigations to examine abstract concept formation in songbirds, and perception of songbird vocalizations in pigeons. This talk will include our recent findings of songbird category perception, songbird abstract concept formation (same/different task), and early results from pigeons’ processing of songbird vocalizations in a same/different task. Our findings indicate that (1) categorization in birds seems to be most heavily influenced by acoustic, rather than genetic or experiential factors (2) songbirds treat their vocalizations as perceptual categories, both at the level of the note and species/whole call, (3) chickadees, like pigeons, can perceive abstract, same-different relations, and (4) pigeons are not as good at discriminating chickadee vocalizations as songbirds (chickadees and finches). Our findings suggest that although there are commonalities in complex auditory processing among birds, there are potentially important comparative differences between songbirds and non-songbirds in their treatment of certain types of auditory objects.
The effect of a middle layer on ultrasonic wave propagating in a three-layer structure
Authors: Mabuza Raymond B. , Netshidavhini Ngeletshedzo
Published: May 2013

In this paper, the focus of attention is on the effect of an elastic middle layer on the propagation behavior of ultrasonic waves. Systematic parametric studies are conducted to quantify the effects of the middle layer upon the ultrasonic wave propagation, including its thickness and acoustic impedance. We treat this problem analytically and numerically. The three-layer structure is also used to investigate the influence of the imperfect interfaces between two outer layers and a middle layer on the ultrasonic wave propagation. The theoretical analysis considers successive reflections of waves radiated by the transmitting transducer. The output signal is a superposition of successive reflections. Our results demonstrate clearly that there is significant influence of the middle layer in our three-layer problem. Various aspects of our approach are discussed and numerical examples are used to illustrate the suitability of our approach. Some details about the numerical methods employed are also given. The results are presented and discussed.
Acoustic and musical features of emotional response to orchestral gestures
Authors: Goodchild Meghan
Published: May 2013

Recent empirical research indicates the impact of prominent changes in instrumentation on the listening experience: several studies suggest that timbral changes evoke music-induced emotions. However, orchestration remains an underdeveloped area of music theory. A model of orchestral gestures defined by changes in instrumentation in terms of time course (gradual or sudden) and direction (addition or reduction) is presented. An exploratory behavioral study that tested the perceptual relevance of orchestral gestures on listeners’ continuous ratings of emotional intensity was conducted. We demonstrate a new type of visualization that illustrates the relative textural density of each instrument family over time combined with other time-varying parameters extracted from the signal (loudness, spectral centroid, tempo, and roughness) and calculated from the score (instrumental texture, melodic range, and attack density). In addition to quantitative and qualitative comparison of similar orchestral gestures across pieces, we use this method to study the interaction of specific instrumentation changes and other musical parameters. Through discussion of the visualizations, we highlight relationships between the perceptual and musical/acoustical dimensions and quantify elements of the temporality of these experiences.
Timbre saliency vs. timbre dissimilarity – What is the relationship?
Authors: Chon Song Hui , McAdams Stephen
Published: May 2013

We have proposed the notion of timbre saliency as the attention-capturing quality of timbre. The definition of saliency requires an object to stand out with respect to its surroundings, implying dissimilarity between the object and its neighbors. What then might be the relationship between timbre saliency and timbre dissimilarity? A classic timbre dissimilarity experiment and a timbre saliency experiment were carried out with 20 participants on the same set of stimuli. Multidimensional scaling revealed a two-dimensional dissimilarity space. Using the features obtained from the Timbre Toolbox [Peeters et al., J. Acoust. Soc. Am. 130, 2902–2916 (2011)], the first dimension shows a high correlation with spectral centroid [r(13) = 0.845, p < 0.0001] and spectral spread [r(13) = 0.855, p < 0.0001], both based on the ERB-FFT model spectrum, and the second with the attack time [r(13) = -0.692, p = 0.004] and power spectral crest [r(13) = 0.732, p < .005]. This confirms spectral centroid and attack time as two major acoustic correlates of timbre dissimilarity. The saliency dimension shows a moderate correlation with the second dimension [r(13) = 0.578, p = 0.0241] but not with the first dimension [r(13) = 0.182, p = 0.517], suggesting that the saliency might be more related to the temporal characteristics of timbre.
Position optimization of Helmholtz resonator in ducts using a genetic algorithm
Authors: Nunes Maria A. , Silva Gabriela
Published: May 2013

The Helmholtz resonators (HR) are classic reactive mufflers used to attenuate noise at low frequencies mainly pure tones propagating in ducts from venting systems. In industrial environments the equipments layout, the maintenance and operation purposes limit the installation of this kind of device in terms of space and location. As part of the muffler design it is necessary to considerate these restrictions and an optimization process may necessary in order to increase its acoustic performance. Keep in mind that in real application the downstream radiating end of the duct must be modeled as an open end radiating into free space, the insertion loss (IL) parameter is more proper for evaluating the HR's performance than the transmission loss. Using the IL to estimate the effectiveness of the acoustic filter, the main purpose of this paper is to numerically analyze and maximize this parameter in the maximum attenuation frequency considering position restrictions (bounds constraints) in a duct. An evolutionary search algorithm (GA) has been applied in order to solve the best position for a fixed shape HR in a duct. The finite element method was used to model the acoustic system HR/duct. The pressure data and the optimization step were processed in Matlab®. For optimal positions the results reveal an increase of 19 dB in the IL parameter at the desired frequency. To verify the sensibility of the methodology simulations were performed varying some GA parameters.
Design and positional accuracy of straight-path traversing room acoustic measurement system based upon low-cost servo motor and light-weight multi-field microphone
Authors: Ellingson Roger M. , Bock Guillaume J.
Published: May 2013

The construction and operation of a straight-path traversing, acoustical microphone-based, measurement system is described. The system was designed to support test room qualification procedures such as prescribed in standards ANSI S12.35-1990 and Annex A of ISO 3745-2003. Major system components include a taut line suspending a sliding microphone carriage drawn by a string attached to a rotating drum. Central to the overall light-weight, low-power, mechanical design is the physically small Bruel & Kjaer 4961 microphone, holder, preamp, and signal cable whose multi-field response characteristic should well support accurate room qualification measurements. The battery-powered drum drive mechanism is built using the servo motor, wheels, and gears from a Lego Mindstorms NXT kit. Precision motor rotation is remotely programmable over the NXT controller’s wireless Bluetooth interface. Commonly available sport fishing tackle composes the majority of the suspension assembly. A software interface library is also described which enables PC-based applications to automate microphone positioning in synchrony with source emission, signal acquisition, and analysis. The system has been used to document the free-field characteristic of a perimeter loudspeaker array with centrally located listener in a fully anechoic chamber environment. Together with construction and operational detail, results indicating overall microphone positioning accuracy and reliability are presented here.
Phase-based dispersion analysis of borehole acoustic logs
Authors: Assous Said , Linnett Laurie , Elkington Peter
Published: May 2013

The dispersive behavior of acoustic waves in boreholes is of interest in the evaluation of reservoir rocks, particularly from the point of view of near wellbore stress distribution. It is also used as a quality control on dipole sonic calculations that estimate formation shear slowness from the low frequency asymptote of the flexural wave slowness. Multiple methods are available for dispersion analysis; the paper reviews the most commonly used, including the Prony and the spectral semblance methods, and proposes a new phase-based analysis technique that has the benefit of improved slowness resolution. The methods are applied to synthetic and real data sets, and results compared. The new method is show to have lower slowness uncertainty for any given frequency, and the upper and lower frequency limits for which dispersion can be calculated is also extended.
Touch the sound: The role of audio-tactile and audio-proprioceptive interaction on the spatial orientation in virtual scenes
Authors: Altinsoy M. Ercan , Stamm Maik
Published: May 2013

Being able to localize objects in the space close to the body is an important prerequisite for precise object interaction. It is also very important for the spatial orientation in virtual scenes. Since sound is usually produced by the vibrations of a body, sound emitting objects, such as shaver or hair dryer, provide both auditory and haptic information. This study focuses on auditory-haptic localization in the spatial domain. We carried out two experiments to investigate the interaction effects. In the first experiment, the influence of tactile signals on auditory localization task was investigated. Similar to the ventriloquist effect from auditory-visual interaction, the results of the first experiment show that the perceived location of auditory stimuli is influenced by tactile stimulation. The results also indicate some hints that there may be an audiotactile precedence effect. In the second experiment, the influence of auditory signals on proprioception was investigated. The results show that the auditory and proprioceptive information can be combined in such a way that the localization errors in a virtual scene are minimized.
Evaluation of an acoustic metamaterial leaky-wave antenna
Authors: Naify Christina J. , Layman Christopher N. , Martin Theodore P. , Calvo David , Orris Gregory J.
Published: May 2013

An acoustic projector array, which can be steered between ± 90 degrees backfire to endfire directions based solely on input frequency, is presented using a combination of transmission line (TL) analysis and negative index metamaterial ideas. An acoustic version of a leaky wave antenna, this TL structure is composed of acoustically loaded membranes (acoustic masses) and open channels (acoustic shunts). This type of TL structure had been shown previously to have broadband negative index behavior below a cutoff frequency, and positive index behavior above the cutoff frequency. By carefully designing the geometry of the acoustic elements, continuous scanning with no acoustic bandgap was achieved. The fast-wave radiation band of the antenna was determined using a lumped acoustic parameter method. Angle of radiation of the acoustic waves out of the acoustic shunts was continually scanned backfire-to-endfire, including broadside. Applications of this antenna structure include both source and sensing technologies. Finite element analyses and acoustic circuit analysis were used to predict the angle of radiation of the antenna which agreed with experimentally obtained results. [Work supported by the Office of Naval Research.]
The modeling of wheel squeal in the time domain and its validation
Authors: Liu Xiaogang , Meehan Paul A.
Published: May 2013

Wheel squeal is a tonal noise generated when a train negotiates a curve, whose sound pressure level is normally 30 dB above rolling noise. The sound pressure level of wheel squeal has been shown to increase with the angle of attack and rolling speed in both field and laboratory tests, but the causes behind the manner of increase are still unknown. To investigate this, a model in the time domain was developed by integrating the contact mechanics with the vibration of the wheel to demonstrate how the nonlinear friction creep behavior interacts with the wheel vibration. This model simulated the vibration velocity of the testrig wheel at different rolling speed and angle of attack. The results correlate well with the recorded sound pressure level of wheel squeal. The lateral creepage and lateral force in various situations were also simulated. It was found that due to the interaction of wheel vibration with lateral force and lateral creepage the vibration velocity amplitude of the wheel at a high angle of attack and rolling speed is larger. This explains why the sound pressure level of wheel squeal also increases in the same manner. The phenomenon is explained theoretically using the mechanics based model.
Study on Doppler effects estimate in underwater acoustic communication
Authors: Xiao Zhang , Xiao Han , Jingwei Yin , Xueli Sheng
Published: May 2013

Two estimate methods of the Doppler effects in mobile underwater acoustic communication have been proposed. For the first method the Doppler coefficients are obtained by estimating frequency change of CW impulse signal with notch filter. For the other method the Doppler coefficients are obtained by estimating chirp rate change of LFM signal with fractional Fourier transform (FRFT). And the performance of the Doppler effects estimation method based on notch filter or the FRFT are compared by the computer simulation. The advantages, shortcoming and the application occasion of the two methods are elaborated. The effectiveness and robustness of the two methods have been proved. Key Word: Notch Filter, Fractional Fourier transform, Doppler Effects, Underwater Acoustic Communication
Influence of multipaths on coherent acoustic communication in shallow water channel
Authors: Son Su-Uk , Choi Jee Woong
Published: May 2013

In shallow water communication channel, acoustic interactions with sea surface and bottom interfaces cause the inter-symbol interference that hinders the efficient and reliable communication. In this case, signal-to-multipath ratio (SMR) rather than signal-to-noise ratio can be used as an indicator to describe the quality of the communication channel. However, it is difficult to estimate precisely the SMR from the measured communication data. In this talk, we propose the energy fraction of the channel impulse response existing within one symbol duration as an alternative to SMR. Communication experiment was conducted on the southern coast of Korea in waters 45 m deep in source-receiver ranges of 100 m to 1 km. The bit-error-rate performance is compared to the energy fraction in one symbol duration. In addition, the correlation between the energy fraction in a symbol and SMR is investigated through a Monte Carlo simulation. [Work supported by ADD (Agency for Defense Development, Korea).]
Fast multipole accelerated indirect boundary elements for the Helmholtz equation
Authors: Gumerov Nail A. , Adelman Ross , Duraiswami Ramani
Published: May 2013

The indirect boundary element method for the Helmholtz equation in three dimensions is of great interest and practical value for many problems in acoustics as it is capable of treating infinitely thin plates and allows coupling of interior and exterior scattering problems. In the present paper, we provide a new approach for treatment of boundary integrals, including hypersingular, singular, and nearly singular integrals via analytical expressions for generic boundary conditions on the both sides of the surface. The fast multipole accelerated boundary element solver in Gumerov and Duraiswami (2009) is extended to incorporate the indirect formulation. The new formulation is compared with the analytical solution of scattering off a disk. Previous authors have not provided such comparisons for an extended range of frequencies. The performance of the method and its scalability are investigated. It is demonstrated that problems with millions of boundary elements can be solved efficiently on a personal computer using the present method.
Estimation of absorption coefficients values of surface materials using a diffusion equation model
Authors: Navarro Juan M. , Lopez Jose J. , Escolano Jose
Published: May 2013

In the auralization process of an enclosure, the right definition of the acoustic properties of the materials is very important. Sometimes, the absorption coefficients of materials in a real room are not found in the literature and their measurement in the laboratory or in-situ are complex. Been the reverberation time of a room and its geometry known, but the absorption coefficient values of the materials that cover the room unknown, it is possible to estimate its values by means of an inverse problem using a room acoustics simulation model. Since the acoustic diffusion equation model is a fast simulation method, it can be used to perform an iterative process to estimate these values. In this paper, we propose a statistical procedure that compares actual measurement values of reverberation time with predictions obtained by the diffusion equation model. This process does an automatically adjustment whose ultimate goal is that the reverberation time predicted values do not differ from those measured in situ by more than 5%. As a preliminary work, this algorithm is tested in a cubic room obtaining satisfactory results, but can be extended to be employed in more complex geometry rooms and even with non homogeneous distribution.
The sensitivity of hearing-impaired adults to acoustic attributes in simulated rooms
Authors: Whitmer William M. , McShefferty David , Akeroyd Michael A.
Published: May 2013

In previous studies, we have shown that older hearing-impaired individuals are relatively insensitive to changes in the apparent width of broadband noises when those width changes were based on differences in interaural coherence [Whitmer et al., J. Acoust. Soc. Am. 132, 369–379 (2012)]. This insensitivity has been linked to senescent difficulties in resolving binaural fine-structure differences. It is therefore possible that interaural coherence, despite its widespread use, may not be the best acoustic surrogate of spatial perception for the aged and impaired. To test this, we simulated the room impulse responses for various acoustic scenarios with differing coherence and lateral (energy) fraction attributes using room modeling software (ODEON). Bilaterally impaired adult participants were asked to sketch the perceived size of speech tokens and musical excerpts that were convolved with these impulse responses and presented to them in a sound-dampened enclosure through a 24-loudspeaker array. Participants’ binaural acuity was also measured using an interaural phase discrimination task. Corroborating our previous findings, the results showed less sensitivity to interaural coherence in the auditory source width judgments of older hearing-impaired individuals, indicating that alternate acoustic measurements in the design of spaces for the elderly may be necessary.
Still able
Authors: Still Trent , Butko Daniel
Published: May 2013

In a world where most students are habitually connected to headphones, one student is harnessing power outside the sense of hearing to unite acoustics and craft into particular listening environments. Trent Still is a student, a craftsman, an avid fan of acoustics, and to my surprise legally deaf in one ear. What initially could be viewed as a hindrance within the study of acoustics, has developed into an avenue of expressive talent and determination. As a student of architectural design, Still focuses on materials, connections, and overall aesthetics of the listening environment. For example: in a recent gallery exhibit of handcrafted furniture, one of Trent’s entries was a pair of handmade loudspeaker enclosures that were French cleated to the wall. They were not merely wall mounted; they were wall dependent. The wall cavity between framing members and the wall finish was part of the installation; thereby actively integrating acoustics into architecture. This paper does not focus solely on one student; it is about unequivocal enthusiasm for acoustical craft within inhabitable space. No matter what seems like a disadvantage or disability, students and educators can work together to ascertain visual and auditory beauty. Sight and sound are uniquely codependent.
Computing cumulative sound exposure levels from anthropogenic sources in large data sets
Authors: Martin Bruce
Published: May 2013

The goal of many underwater acoustic environmental assessments is to characterize the soundscape in an area before, during, or after an anthropogenic activity. The assessment determines the range of baseline noise levels from natural and anthropogenic sources and the contribution of the new anthropogenic activity. The noise levels are considered in aggregate for possible effects on the environment. It is accepted that the effects of anthropogenic noise on marine life depend on the intensity and duration of exposure, the frequency content of the sound relative to the hearing abilities of the species, and the behavior context of the species exposed to the sounds. A growing body of scientific evidence is being analyzed to establish threshold sound levels and dose-response curves for injury or behavioral disturbance effects to marine life. Recent research is also raising new questions about the most appropriate ways to compute ambient sound levels and exposure metrics. In this paper, we present our methods for quantifying ambient sound levels and anthropogenic sound levels from shipping and seismic survey activities in large data sets. We also make recommendations on how to estimate background sound levels in the presence of these sound sources.
Ultrasound-mediated drug delivery with real-time cell permeability measurements
Authors: Anastasiadis Pavlos , Matter Michelle L. , Allen John S.
Published: May 2013

Ultrasound-mediated drug and gene delivery offers a variety of novel possibilities for improved localized treatment of vascular- and cancer-related diseases. This therapeutic application benefits from the use of acoustic radiation force, which facilitates the exposure for enhanced binding from ligand-receptor interactions. The unique merits of ultrasound are the transient increase of cell permeability without any detrimental and irreversible side-effects. The related underlying molecular and cellular pathways of ultrasound-induced permeability and the subsequent recovery of cells are topics of on-going research. Real-time studies of cell behavior during and past-ultrasound exposure have been limited by the lack of appropriate techniques. The electric-cell impedance sensing (ECIS) technique is a suitable way of studying cell permeability changes in real-time. Its nanoscale sensitivity and speedy acquisition of data allows for the accurate and timely monitoring of cell behavior. Our preliminary results suggest that cells recover within 24–36 h post-exposure. During this time window the cells undergo drastic changes exhibiting an increased permeability of 2.4 ± 0.6 Ω•cm2 compared to 3.8 ± 0.5 Ω•cm2 that normal untreated cells exhibit.
Investigation on the inertial cavitation threshold of micro-bubbles
Authors: Guo Xiasheng , Zhang Dong , Tu Juan
Published: May 2013

Experimental measurements and numerical analyses were performed to investigate the IC thresholds of two commercialized UCAs, albumin-shelled KangRun® and lipid-shelled SonoVue®. The IC thresholds of these two UCAs were measured at varied acoustic pulse lengths and bubble concentrations, according to the IC dose quantifications based on passive cavitation detection (PCD). Then, the shell properties of UCAs were estimated by fitting the measured acoustic attenuation data. Finally, the influences of acoustic pulse length and UCA shell properties on the microbubble nonlinear behaviors were discussed based on numerical simulations, which would give us better understanding of the dependence of microbubble IC threshold on the sonication condition and physical structure properties of the coating shells. The experimental results show that: (1) the IC threshold of UCAs is dependent on the acoustic driving conditions, the shell properties of UCAs and the bubble concentration; (2) for both the lipid- and albumin-shelled UCAs, the IC threshold generally decreases with the increasing UCA volume concentration; (3) IC threshold is observed higher for short-pulse excitation, then its value decreases as the acoustic pulse length increases from 5 to 20 cycles and finally tends to reach a steady state for even longer pulsed exposures.