bluuebunny/crossref_metadata_2025 huggingface dataset:
Individual differences in learning to perceive novel phonetic contrasts: How stable are they across time and paradigms?
Authors: Broersma Mirjam , Dediu Dan , Choi Jiyoun
Published: November 2013

Previous research has shown that learners differ widely in the success with which they learn to perceive novel phonetic contrasts. Little is known, however, about the stability of such differences over time and over paradigms. Are individuals who are good at learning to perceive novel speech sounds consistently good at it, or does the success of learning fluctuate over time, or with the use of different paradigms? First, we investigate the stability of individual differences over time by assessing performance during five (pre- and post-training) test moments on three separate days with one-week intervals. Second, we investigate the stability over paradigms by comparing the two most commonly used tests of speech sound perception, namely discrimination and identification. 70 native speakers of Dutch participated in a series of training and test sessions, during which they were trained to perceive the Korean three-way lenis-fortis-aspirated contrasts /p-p*-ph/, /t-t*-th/, and /k-k*-kh/, which are difficult for them to distinguish. Results showed, first, that individual differences were very stable over time. Second, the correlation between individuals’ discrimination and identification scores was only moderate. Thus, individual differences in learning to perceive novel phonetic contrasts seems to be a stable individual trait over time, but not over paradigms.
The effect of sleep on learned sensitivity to a non-native phonetic contrast
Authors: Earle Sayako , Myers Emily
Published: November 2013

Consolidation during sleep is thought to play a role in integrating newly learned words into the preexisting lexicon (e.g., Dumay and Gaskell, 2007), while the effect is in stabilizing degraded information against decay when learning to map synthesized speech onto native phonology (Fenn, Nusbaum, Margoliash, 2003). In the current study, we investigated the effects of overnight consolidation on discrimination between new (nonnative) phonetic categories. Fifty-four monolingual English speakers were trained to categorize tokens from a non-native dental-retroflex contrast. Half of the participants were trained in the evening, and the other half were trained in the morning. Discrimination ability was tested 8-14 h post-training and 22-26 h post-training in order that the effects of intervening sleep (evening group) or daytime activity (morning group) could be assessed. Discrimination in the trained vowel context improved after the overnight between-session interval in the night group, but declined slightly in the morning group. Both training groups improved in discrimination ability for an untrained vowel context immediately following the overnight between-session interval, but not before. Results suggest that memory consolidation during sleep, proactive interference during native language exposure, or both play a role in non-native phonetic learning.
Acoustic radiation force. Part II: Eigenmode excitation of a scaled target
Authors: Abawi Ahmad T. , Kirsteins Ivars
Published: November 2013

We describe an experiment that we recently performed at the Washington State University test tank where dynamic acoustic radiation forces were used to excite an eigenmode of a 2.5 in. PMMA sphere in water. The dynamic acoustic radiation force was generated by an intense, amplitude modulated ultrasound signal focused on the surface of the sphere whose amplitude modulation frequency was set to generate acoustic radiation forces modulated at a rate matched to an eigenmode of the sphere. A conventional hydrophone was used to listen to the sphere’s acoustic emissions from that particular eigenmode. Unlike conventional acoustic insonification, the dynamic acoustic pressure force is generated by momentum transfer, which creates a mechanical excitation on the object’s surface at a rate equal to twice the modulation frequency, analogous to a hammer striking it. In the experiment, the modulated ultrasound beam was scanned horizontally across the sphere using a computer-controlled actuator with the sphere’s acoustic emissions measured at each position. To confirm and understand the experimental results, the measured sphere’s acoustic emissions were compared to finite element model predictions as a function of horizontal position.
Three-dimensional propagation: Comparison of finite element and coupled-mode solutions
Authors: Ballard Megan S. , Goldsberry Benjamin M. , Isakson Marcia J.
Published: November 2013

Three-dimensional propagation over an infinitely long cosine-shaped hill is studied using finite element and coupled-mode models. The finite element approach is based on a longitudinally invariant solution technique. The solution is formulated in a Cartesian coordinate system and a cosine transform is applied to eliminate the range-independent dimension. The resulting equation is two dimensional and the solution is calculated for a sufficient range of values of the transform variable. Then the spatial solution is obtained using an inverse cosine transform. The coupled-mode model is formulated in a cylindrical coordinate system, and the solution is obtained using a separation of variables. Modal amplitudes are calculated from the horizontally separated part of the Helmholtz equation using a hybrid technique such that a parabolic solution provides the description of horizontal refraction in the azimuthal direction and a stepwise coupled-mode technique accounts for mode-coupling in the radial direction. The finite element model provides a highly accurate result, limited only by the discretization of the environment and sampling of the cosine transform integral. The coupled-mode solution is approximate, but an examination of the model amplitudes is used to gain insight into the effects of environmental inhomogeneities on the acoustic field. [Work supported by ONR.]
Information capacity of an acoustic field in a Pekeris waveguide with an absorbing bottom and spatially correlated surface noise field
Authors: Finette Steven I. , Williams Earl
Published: November 2013

It is well known that the Shannon theory of information sets an asymptotic bound on the maximal rate of transmission of information through a channel with negligible probability of error. This rate, known as the information capacity, can be computed analytically or numerically and numerous results for the capacity in terrestrial communications have been derived. Most analytic results, however, involve free space propagation while in underwater acoustics, the propagation region is spatially bounded. In this presentation, we consider the information capacity in an ocean waveguide comprised of a uniform sound speed in the water column, a penetrable, absorbing bottom and a correlated surface noise field described by the Kuperman-Ingenito source sheet model. An expression for the information capacity of the acoustic field in the water column exterior to a distributed source region is determined by first applying singular value decomposition to the Green’s function matrix to obtain independent communication channels and then using Lagrange multipliers to solve a multiply constrained optimization problem involving the mutual information between source and receive regions. [Work supported by the Office of Naval Research.]
Supervised machine learning for estimation of rough bottom anisotropy direction using bistatic acoustic scattered fields
Authors: Fischell Erin M. , Schmidt Henrik
Published: November 2013

An issue when trying to use scattered acoustic fields to classify underwater targets is the strong directional scattering due to anisotropic rough bottom structure that occurs in the 1-5 kHz frequency range. Autonomous Underwater Vehicles (AUVs) are uniquely suited to exploit this three dimensional field with the goal of estimating the anisotropy direction of the bottom roughness. Estimation of the angle of bottom roughness ridges relative to an acoustic source is carried out using a combination of supervised machine learning and AUV behaviors. Anisotropic Goff-Jordan power spectrum bottom scattered fields in 15 degree angle increments are generated using SCATT and OASES acoustic packages. The amplitudes of these fields are sampled into sets of 5-20 AUV waypoints. Support Vector Machine (SVM) regression is used to train a model, and an independent test data set is used to evaluate the validity of the model. A confidence model is constructed and critical waypoints identified using the test set results. The confidence and SVM models can then be used to determine bottom roughness angle in real time, as demonstrated using the LAMSS MOOS-IvP simulation environment.
Generation and propagation of oceanic T-waves using elastic parabolic equation solutions
Authors: Frank Scott D. , Collis Jon M. , Odom Robert I.
Published: November 2013

Oceanic T-waves are essential for location and identification of seismic sources since they travel long distances in the ocean and are typically the largest signals received at hydrophone arrays or coastal monitoring stations. T-waves either link directly into the SOFAR channel by conversion of elastic wave energy at a downward sloping interface between the elastic and fluid media, or are generated when elastic energy couples into low order acoustic modes due to bathymetric inhomogeneities. Elastic parabolic equation solutions will demonstrate generation and long range propagation of oceanic T-waves in the water column when the source is located in an elastic ocean bottom. Elastic parabolic equation solutions will be used to describe effects of ocean bottom parameters on transmission characteristics of a sloping boundary. The impact of small-scale bathymetric changes, for example due to a rough ocean bottom, will be characterized by averaging acoustic wavenumber spectra resulting from multiple bottom realizations. Favorable characteristics for T-wave generation will be determined. The impact of large scale bathymetry changes, such as a seamount or underwater ridge, will also be discussed. [Work supported by ONR.]
Multi-static scattering characteristics of submerged objects with experimental investigation
Authors: Ji Yoon Hee , Byun Gi Hoon , Kim Jea Soo , Bae Ho Seuk , Kim Woo Shik
Published: November 2013

The scattering characteristics of target echoes are essential for detecting and classifying the submerged objects. The target strength, which is widely used in mono-static sonar system, is also important in multi-static sonar system to identify the submerged target. In this presentation, a series of experiments in the acoustic water tank was conducted to measure the target echoes from submerged cylinder-shaped target with multi-static measurement system, which consists of a single transmitter and 16 receivers. The target strengths are presented in 2-dimensional plane as a function of receiver position according to target aspect angle. The numerical simulation results based on Kirchhoff approximation are presented to explain some characteristics of the measured multi-static target echoes. [Work supported by Agency for Defense Development, Republic of Korea.]
Fluctuations of arriving narrowband signal’s direction in horizontal plane in shallow water
Authors: Katsnelson Boris , Grigorev Valery
Published: November 2013

Directions of amplitude (envelope) and phase fronts in horizontal plane of signals with some width of spectrum coming to receiving array in shallow water are studied. As an example experiment Shallow Water 2006 is analyzed, where LFM signals of the frequency 300±30 Hz were used for acoustical sounding on the distance ~20 km. Visible length of horizontal part of L-shaped array was ~200 m. It was shown that fluctuations of direction of phase and amplitude fronts took place with angle between them about 2.5°±1.5° were registered. Results are interpreted as manifestation of frequency dependence of horizontal refraction initiating variation of horizontal angle of coming rays from pulse to pulse during time of observation. [Work was supported by RFBR and BSF.]
A new type flextensional transducer
Authors: Lan Yu , Lu Wei , Sang Yongjie , Li Kuan
Published: November 2013

In a field of an oceanographic survey, low frequency sound wave is often used because of low attenuation and good propagation characteristic in water. It is well known that flextensional transducer is a typical low frequency underwater source for oceanographic research, utilizing flexural vibration to realize low frequency radiation with small size. However the size of traditional flextensional transducer becomes relative large when the frequency decreases to a few hundred Hertz, and it is still a difficult problem to solve. A new type of class IV flextensional transducer was proposed, and original piezoelectric ceramic stacks were replaced by three groups of small class IV flextensional transducers, resulting in frequency decrease and volume displacement expansion. Make use of ANSYS finite element software, the new class IV transducer was modeled and analyzed. The experimental data showed the frequency of this new transducer design obviously decreased compared with traditional IV flextensional transducer at the same size. Key words: Flextensional transducer; low frequency; small size; Finite Element Method
Computational modeling of acoustic wavefronts propagating in an underwater environment with uncertain parameters
Authors: Martinelli Sheri
Published: November 2013

High frequency simulation of underwater sound propagation is a vital part of modeling and simulation of acoustic systems for evaluation and performance prediction. Existing simulations use deterministic ray tracing to propagate the acoustic field and simulate uncertainty by varying results according to basic distributions (e.g., adding ”jitter” to ray arrival angle). Rather than incorporate randomness as a form of post-processing, this work seeks to model uncertainty where it exists in the underwater environment where it is easier to specify, and then propagate the relevant random quantities through the system applying stochastic collocation to an existing deterministic model. Further, this work addresses the drawbacks of ray tracing by taking the deterministic method to be a model that computes propagation of entire wavefronts rather than rays, thus maintaining error control over the physical domain. To this end, generalized polynomial chaos expansions are applied to a level-sets based wavefront propagation method to model the effects of uncertain parameters in an underwater environment. This approach allows for not only simple extraction of the process moments, but also yields an expression for the wavefronts in terms of random variables which can readily be simulated. [Work supported by ONR.]
Modeling of underwater noise from pile driving using coupled finite element and parabolic equation model with improved parabolic equation starting field
Authors: Park Jungyong , Seong Woojae , Lee Keunhwa
Published: November 2013

An offshore wind farm will be constructed in the Yellow Sea, west of Korean Peninsula, where there are extensive fishing activity and numerous fishery farms. To study the effect of underwater piling noise on fishing and marine lives, we model the pile driving noise propagation using coupled FE and PE model. The near-field noise is computed by FE model, considering detailed specifications of the pile driving system. We apply 2D axis-symmetric geometry and utilize acoustic structure interaction analysis in the frequency domain. The FE results are used to compose the starting field for PE model, where appropriate range selection is an important factor to cover most of the contributing ray paths. Extrapolation technique to compensate the lack of FE data and the numerical filtering method to smooth the FE result are discussed. In the far-field, the noise propagation is modeled by the split step Pade PE algorithm. The improved PE starting field seems to give refined result than previous coupled model.
Investigating biosonar automatic gain control in a dolphin using auditory evoked potentials
Authors: Finneran James J. , Mulsow Jason , Houser Dorian S.
Published: November 2013

Studies with echolocating odontocetes suggest that forms of automatic gain control mediate auditory electrophysiological responses to target echoes. This study used a phantom echo generator and auditory evoked potential measurements to examine automatic gain control in a bottlenose dolphin. Auditory evoked potentials to outgoing clicks and incoming echoes were recorded for simulated ranges from 2.5 to 80 m. When geometric spreading loss was simulated, echo-evoked potential amplitudes were essentially constant up to 14 m and progressively decreased with increasing range. When the echo levels were held constant relative to clicks, echo-evoked potential amplitudes increased with increasing range up to 80 m. These results suggest that automatic gain control maintains distance-independent echo-evoked potential amplitudes at close range, but does not fully compensate for attenuation due to spreading loss at longer ranges. The automatic gain control process appears to arise from an interaction of transmitter and receiver based processes, resulting in a short-range region of distance-independent echo-evoked potential amplitudes for relevant targets, and a longer-range region in which echo-evoked potential amplitudes are reduced. [Work funded by SSC Pacific Naval Innovative Science and Engineering (NISE) program.]
A simulation model of cyclic variation of red blood cell aggregation under Couette and Poiseuille flows
Authors: Kong Qi , Nam Kwon-Ho , Paeng Dong-Guk
Published: November 2013

The aggregation of red blood cells (RBCs) is a reversible phenomenon in which RBCs form a pile or network at low shear rate via the interactions of electrostatic and aggregating forces. In previous experimental results under both Couette and Poiseuille flows, cyclic variations in blood echogenicity were observed but their cyclic patterns were different. In this paper, a two-dimensional particle model capable of mimicking the main characteristics of RBC aggregation kinetics was proposed to elucidate the different effects of hemodynamics under Couette and Poiseuille flows on RBC aggregation. In simulation results, cyclic variation of RBC aggregation was observed but its magnitude of mean aggregate size (MAS) was not changed by variations of velocity and stroke rate under Couette flow. These results are in agreement with the experiment results. In contrast, the simulation results under Poiseuille flow revealed that cyclic variation of RBC aggregation and its MAS magnitude were changed by variations of velocity and stroke rate. As stroke rate increased from 20 to 120 beats/min, the phase of MAS variation compared with velocity profile was shifted. These simulation results may provide the theoretical explanation of the different experimental results of cyclic variation of RBC aggregation under Couette and Poiseuille flows. [Work supported by NIPA-2013-H0401-13-1007 and 2013R1A1A2043478.]
Hot topics: Recent discoveries using new recording methods in animal bioacoustics
Authors: Simmons James A.
Published: November 2013

Recent research has successfully addressed a variety of difficult questions about animal acoustic communication and orientation by taking advantage of two related techniques—on-board recording or telemetry of animal sounds or neurophysiological signals during behavior, and acoustic tracking of the locations of animals using arrays of microphones or hydrophones coupled with efficient software for processing the time-of-arrival of sounds. These methods have great power for relating the locations and movements of animals to their acoustic signals and auditory responses, but they have limitations that have to be taken into account if their potential is to be realized. The examples to be presented highlight discoveries that have been made using these methods. They have broadened our understanding of how animals interact acoustically with each other according to their spatial distribution and proximity, how they dynamically regulate auditory sensitivity.
The importance of the relationship of acoustics and sustainability
Authors: Woolworth David S.
Published: November 2013

Sustainability has become a keyword in the architecture and the building industry, in no small part driven by the development of standards such as IGBC and LEED. The refined definition of sustainability, however, depends on the viewpoint: economic, social, or environmental. Acoustics of buildings (and the environment) has an intrinsic link to sustainability that should be highlighted to prevent the sidelining of architectural acoustics in building budgets and architectural programs of study. This paper examines the concept of sustainability as it relates to the building industry and architectural acoustics, and provides a summary of work in this area to outline this relationship to illuminate the importance of acoustics in sustainability.
Relating acoustics and thermal performance
Authors: Woolworth David S.
Published: November 2013

Good thermal performance of a building produces a tangible financial return to the owner that comes from energy savings. While some not-as-directly tangible returns such as functionality or productivity can be exacted from good acoustics, some acoustic treatment materials or techniques also exhibit beneficial thermal properties. This paper examines and quantifies some of these acoustic approaches that allow thermal benefits to “piggy back” and help embed the acoustic design into the project so that it is not so easily removed in the value engineering phase of the project.
Wavepacket noise source model for microphone array data analysis of hot supersonic jets
Authors: Morris Philip , Dougherty Robert , Nelson Chris , Cain Alan , Brentner Kenneth
Published: November 2013

Phased arrays of microphones have proved themselves to be a powerful tool for aeroacoustic investigations. There are many different algorithms for processing the resulting data, including classical beamforming, its modern derivatives, Linear Programming, and Generalized Inverse Methods. The current work stems from a recognition that, for configurations with extended coherent sources (such as hot supersonic jets), the Generalized Inverse Method may be preferred, but that its accuracy can be improved by improving the underlying source model that it uses. We examine a wavepacket-based source model for analysis of the noise emitted from hot supersonic jets. This approach provides a more physically realistic representation of the jet noise sources than previously used. The model is tested using data obtained from numerical simulations as measured at a “virtual” array of microphones. The resulting generalized inverse method analysis is then used to predict noise at a farfield arc, and this prediction is compared with that from a conventional Ffowcs Williams-Hawkings acoustic analogy prediction. Initial results with the new wavepacket source model are encouraging, with improved directivity predictions and elimination of some spurious noise sources. The results of the ongoing model development will be included in the final paper.
Infrasonic emissions from aircraft wake vortices: Field installation
Authors: Shams Qamar , Knight Howard K. , Zuckerwar Allan J.
Published: November 2013

An infrasonic field installation was set up at Newport News-Williamsburg International Airport in early 2013. The system is made up of three PCB 377M06 microphones installed into non-porous subsurface windscreens [POMA 1pNS9, 18, 040005 (2013)], which limit the bandwidth to 100 Hz. The microphones are placed 250 ft (76.2 m) orthogonal to the runway and 200 ft (60.96 m) apart. The data acquisition system is the B&K Pulse, from which time histories, spectra, and coherence between microphone channels are derived. The system is placed inside an instrumentation vehicle just behind the center microphone. Perforated drainage hoses are installed from the subsurface windscreens to adjacent drainage ditches and weight is added to the windscreens for additional stability. The drainage system has proved successful even on occasions of heavy downpour, revealing a truly all-weather system. A pistonphone calibration at 14 Hz in the field reveals that the three channels are matched to within 2 dB. This capability permits long-term monitoring of the health of the system. A sample time history of signals received from an aircraft takeoff will be presented.
A unified model of hysteresis and relaxation in geophysical materials
Authors: Ostrovsky Lev A. , Lebedev Andrey V.
Published: November 2013

A physical model of stress-strain dynamics and long-time relaxation (slow time) in structured media such as the rock is suggested. It is based on an adhesion mechanism (JKR model) for inter-grain contacts which implies the surface force potential with a barrier. This model results in a unified description of the classical nonlinearity, stress-strain hysteresis, and logarithmic relaxation law for sound velocity and, hence,for the frequency of nonlinear resonance in samples of structured materials. Estimates of a characteristic volume of interacting contacts give close values for a variety of consolidated materials. Propagation of waves in such materials is briefly considered. For a weak (linear) testing wave, the logarithmic relaxation occurs if the classical quadratic nonlinearity is added to the stress-strain relation.
A hybrid geostatistical-acoustical model for estimating single-event noise levels from noise monitor data
Authors: Nykaza Edward T. , Atchley Anthony A.
Published: November 2013

A hybrid geostatistical-acoustical (geo-acoustic) model is proposed as a method for estimating single-event noise levels over a large region from data obtained from a small number of noise monitors. The geo-acoustic model is developed using geostatistical theory and an environmental acoustic-propagation-based regression model. The model is compared to several benchmark models and is evaluated under controlled and simulated meteorological conditions, noise monitor geometries, and areal sensor densities. The results show that it is possible to obtain accurate estimates of the SPL and the variance—associated with the SPL estimates—over a large region with a small number of noise monitors. The proposed geo-acoustic model is significantly more accurate than other commonly used spatial interpolation models, especially when there are few noise monitors and when the estimation point is extrapolated from the noise monitor data.
Ultrasonic transducers and monitoring methods for high resolution structural health monitoring
Authors: Grill Wolfgang
Published: November 2013

An overview is presented covering novel methods for structural health monitoring (SHM) including the scientific background of different, lately developed methods, dominantly based on the transport properties of guided ultrasonic waves. Among the issues presented and discussed are mode and velocity selective contact and non contact transducers including testing methods for array transducers allowing, respectively, adapted optimized operation. Principles of operation, including holographic and tomographic imaging and high resolution integral temporal monitoring, are presented. Special attention is given to wideband excitation in combination with spectroscopic and dispersive imaging based on respective data acquisition and evaluation. Furthermore, compensation methods for temperature variations by acoustic thermometry are presented. The advantages and possible shortcomings of locally selective and integral SHM are discussed and examples are presented for aircrafts, civil structures, and their sections.
Speech assist: An augmentative tool for practice in speech-language pathology
Authors: Utianski Rene L. , Sandoval Steven , Lehrer Nicole , Berisha Visar , Liss Julie
Published: November 2013

Dysarthria affects approximately 46 million people worldwide, with three million individuals residing in the US. Clinical intervention by speech-language pathologists (SLPs) in the United States is supplemented by high quality research, clinical expertise, and state of the art technology, supporting the overarching goal of improved communication. Unfortunately, many individuals do not have access to such care, leaving them with a persisting inability to communicate. Telemedicine, along with the growing use of mobile devices to augment clinical practice, provides the impetus for the development of remote, mobile applications to augment the work of SLPs. The proposed application will record speech samples and provide a variety of derived calculations, novel and traditional, to assess the integrity of speech production, including: vowel space area, assessment of an individual’s pathology fingerprint, and identification of which parameters of the intelligibility disorder are most disrupted (e.g., prosody, vocal quality). The individualized selection of desired information for incorporation into a report template will be available. The reports will mimic those generated manually by SLPs today. The automation of this assessment will allow SLPs to treat patients remotely, allowing for the widespread, worldwide impact of high skilled assessment, something currently lacking in underdeveloped parts of the world.
The echolocating phone app
Authors: Hague David A. , Tuladhar Saurav
Published: November 2013

Acoustic echolocation systems have a multitude of applications including test/measurement, noise cancellation, and object detection. Current smartphone technology possesses the necessary computing power to implement sophisticated echolocation systems on smartphones. This provides the smartphone user with the ability to perform complicated acoustic measurement tasks in any situation and environment. This project implements an active sonar system on an Android smartphone. The sonar system has three main modes of operation: object detection and ranging, object velocity estimation, and joint object range and velocity estimation. Each of these operational modes are accomplished by utilizing one of the phone’s speakers as a transmitter and one or more of the microphones as a receiver. The app employs a simple Graphical User Interface that allows the user to switch between the modes of operation and observe/analyze object data. Additional functionality may include the ability to write object data to various data formats for offline processing and analysis. Because this app employs several modes of operations, there are several potential commercial applications including measuring a room’s acoustic impulse response or a vehicle speed gun as well as many educational apps exploring various acoustic phenomena.
Acoustical Society of America Silver Medal in Biomedical Acoustics
Authors: Hynynen Kullervo H.
Published: November 2013

The Silver Medal is presented to individuals, without age limitation, for contributions to the advancement of science, engineering, or human welfare through the application of acoustic principles, or through research accomplishment in acoustics.
Developing criteria for identifying acoustical defects
Authors: LoVerde John , Dong David W.
Published: November 2013

In a construction defect lawsuit of a multifamily residential project, the determination of whether a defect exists often hinges on the criteria applied. For many acoustical items, such as plumbing and HVAC noise, there are no code requirements but a number of guidelines and recommendations. For items such as noise from traffic or airborne and impact sound isolation between units, minimum code requirements exist, but often a more stringent standard is applied. How does an expert decide when it is appropriate to apply an acoustical standard that is beyond that required by building codes? Project drawings, marketing materials, homeowner regulations, and other documents can provide indications of the intent and promise of the project as it relates to acoustical issues. The process is discussed with examples from recent cases.
Bioacoustic contributions to the soundscape
Authors: Hildebrand John , Baumann-Pickering Simone
Published: November 2013

The soundscape, the combination of all sounds found in the environment, has been divided into three components: geophony—sounds that are generated by non-biological sources such as wind and waves; biophony—sound generated by animals, excepting humans; and anthrophony—sound generated by human activities. The soundscape can be further divided by spatial, temporal, and frequency band variations. Spatial variations occur both owing to proximity to various sound sources and to the sound propagation environment. Temporal variations occur on seasonal, lunar, daily, and other cycles. Use of different frequency bands may be a response to spatial and temporal overlap of sounds. In this session, we consider biological components of the soundscape and how sounds produced by animals interact with each other and with non-biological and anthropogenic sounds. We suggest that studies using long-term passive acoustic monitoring may take a more holistic approach to analysis using the concept of soundscape. This approach emphasizes the connections and relations between sound events, rather than focusing on the extraction of individual sound events. The session draws on data collected both in terrestrial and marine settings to illustrate how the soundscape concept can be applied to better understand animal use of sound.
Passive acoustic monitoring of biological and anthropogenic sounds at America’s first offshore wind farm
Authors: Mooney T. Aran , Kaplan Maxwell B. , Lamoni Luca , Boucher Aimee , Sayigh Laela S.
Published: November 2013

Cape Wind, situated in Nantucket Sound, Massachusetts, is poised to become America’s first offshore windfarm. Our objective is to establish baseline (pre-construction) sound levels of human and biological activity, including diel and seasonal variability of various sound types, at the construction site and three nearby comparison sites. Acoustic recorders have been deployed since April 2012, recording on a 10% duty cycle (sample rate: 80 kHz). Biological contributions to the local soundscape are primarily fish sounds, with the dominant signal likely being cusk eel (Family Ophidiidae) calls. These calls, which are composed of stereotyped pulses with an average bout duration of 3.3 ±0.8 s and mean peak frequency of 1030 ±200 Hz, show both seasonal and diel variation. Dense choruses were detected during summer (July), but limited activity occurred in the fall and winter. During vocal periods, detections occurred throughout the day but peaked near dusk. Vessel traffic also showed diel and seasonal trends, with peaks during the daytime and in the summer, which indicates that boat activity can be tracked acoustically. These trends in biological and anthropogenic activity provide key baseline records for evaluating the influence of windfarm construction and operation on a local US soundscape.
Ambient noise modeling using sound field reciprocity
Authors: Barclay David R. , Lin Ying-Tsong
Published: November 2013

An efficient numerical calculation of the vertical and horizontal coherence of the noise field in the ocean due to a distributed sheet of sources can be carried out using a parabolic equation (PE) propagation model and the reciprocity property of the complex pressure field. In the case of an infinite sheet of sources near the surface in an infinitely deep, isovelocity ocean, the calculation of vertical coherence using this method is in agreement with the Cron and Sherman model for wind-driven surface noise, as well as with measurements made of vertical coherence in the Philippine Sea. This numerical model also gives the effective surface-listening radius for a single hydrophone by calculating the contribution to the noise field at the receiver from a small noise patch at the surface, as a function of range. The model is capable of calculating the vertical and horizontal coherence (directionality) of the noise field and the depth-dependent surface-listening radius of a hydrophone in a shallow water waveguide and over range-dependent environments, such as a wedge, canyon, or shelf break. Additionally, this technique can be used to calculate the spatial properties of the noise field due a finite patch of surface sources in motion, such as a rainstorm.
Computation of ocean noise fields
Authors: Porter Michael B. , Henderson Laurel J.
Published: November 2013

Ships and winds provide two key examples of sound sources that “illuminate” the ocean. In recent years, we have seen a great interest in such noise fields. It has become clear that this noise field provides an important signal that can be used to image the environment and the ocean bottom in particular. Separately, conservationists have become very interested in the fields in terms of their impact on marine life. The modeling of such noise fields provides interesting challenges. First, the noise field is the result of not just a single propagation calculation but a fan of calculations connecting a receiver location to all the noise sources. Second, the characteristic cylindrical spreading from a point source is counter-balanced nearly perfectly by the increase in area of a cylindrical annulus as we accumulate the contributions of noise sources in range. Thus, the noise can travel to extremely long range. This talk will discuss such noise calculations in terms of both the numerics and the physics. We will discuss numerical options in terms of efficiency and accuracy. In addition, we will discuss the role of environmental uncertainties.
Aeroacoustic applications of acoustic energy harvesting
Authors: Horowitz Stephen B. , Sheplak Mark
Published: November 2013

In this paper, the development and use of acoustic energy harvesting technology as a source of local power for aeroacoustic sensing and control applications is discussed. As an example, the application of acoustic energy harvesting as a primary local power source for aircraft engine noise reduction technology is addressed. Noise generated in turbofan engine nacelles can easily exceed 150 dBSPL, presenting a primary motivation for aircraft noise reduction technologies. Adaptive noise control approaches require less power than active methods and can outperform passive techniques (e.g., by actively tuning an otherwise passive system to a changing noise spectrum). Locally sourced power is highly desirable in this application to eliminate cabling in a difficult to access, harsh environment. The low power requirements can be reasonably supplied with harvested acoustic energy, particularly given the large acoustic intensities in and around aircraft engine nacelles. The detailed development approach and experimental results of acoustic energy harvesting using an electromechanical Helmholtz resonator will be presented. Additionally, alternative Helmholtz resonator variants and other aeroacoustic applications of acoustic energy harvesting will be reviewed.
Percussion, performance, pedagogy, and technology: The impact of virtual music Lessons in percussion education
Authors: Krishnamurthy Rohan
Published: November 2013

Real-time net-conferencing software such as Skype and Google Hangout has revolutionized music education in the last decade. This presentation examines the intersections of percussion, performance, pedagogy, and technology with specific reference to South Indian classical Carnatic percussion. Drawing on several scholarly perspectives and ethnographic research in India, various aspects of online teaching will be discussed, including its history and motivations, comparison of online and face-to-face pedagogical repertoire, negotiating audio/video lag or latency, and other significant social and cultural dimensions. Broader implications of online pedagogy in terms of reinforcing musical and intellectual centers, as well as strategies for improving the online learning experience, will be explored. A live, interactive performance on the mridangam, the principal percussion instrument from South India, will follow the presentation.
Expressively actuated percussion instruments and interfaces
Authors: Berdahl Edgar J.
Published: November 2013

Percussion instruments and interfaces can be extended by incorporating actuation with motors. While many prior designs have employed actuation to simply trigger notes, this work emphasizes the importance of the musician's gesture using expressively controlled actuators. This is achieved by implementing force-feedback control of the actuators. For example, the Haptic Drum essentially consists of a drum pad attached to a woofer. Every time that a drumstick strikes the drum pad, the woofer briefly pushes it upward again, adding energy to the motion of the drumstick. In this manner, the Haptic Drum enables musicians to play one-handed drum rolls at optionally superhuman speeds and with arbitrarily complex dynamics. Furthermore, because the musician and the drumstick are inside the feedback control loop, the musician can change the rate of the drum roll by modulating the stiffness of his or her muscles or changing the downward force applied to the drumstick. Conversely, borrowing on technology for remote surgery, expressively actuated percussion instruments can be designed using force-feedback teleoperation. Simply by recording the position of the master haptic device during teleoperation, generalized motor programs can be created for expressively playing percussion instruments. This technology was employed in the composition “When the Robots Get Loose."
Intensity analysis of peak-frequency region in noise produced by a military jet aircraft
Authors: Stout Trevor A. , Gee Kent L. , Neilsen Tracianne B. , Wall Alan T. , James Michael M.
Published: November 2013

Acoustic intensity measurements of the F-22A Raptor are analyzed as part of ongoing efforts to characterize the noise radiation from military jet aircraft. Data were recorded from a rig of microphones and an attached tetrahedral intensity probe at various locations to the sideline and aft of the aircraft. Recently, techniques such as coherence, similarity spectra analyses, and near-field acoustical holography have indicated a peak-frequency region comprised of two maxima that have very different radiation directionalities. Acoustic vector intensity is analyzed as a function of frequency to further assess the behavior of this double-peak phenomenon, which is not accounted for by current jet noise models. The results thus far confirm the discrete nature of the peaks and their directionalities.
New results exploiting correlation in wind noise to enhance detection of transient infrasound
Authors: Frazier William G.
Published: November 2013

A previous ASA presentation introduced a signal processing method for exploiting the correlation observed in pressure fluctuations measured by infrasound sensors on small spatial-temporal scales in order to achieve enhanced signal detection and estimation performance. An algorithm based on representing the pressure field with Fourier series and finite-element bases was presented and applied to time series data in the 0.1 to 1.0 Hz band with inter-sensor spacing of 1 m using small domes as wind screens. The coherence of the data was not inspiring, but the performance was consistent with this low coherence. In this presentation new data collected using flush-to-the-earth installed sensors spaced 1 and 0.5 m apart will be presented and analyzed. In addition, application of a generalized least-squares approach to estimating the infrasound signal will be examined and compared to the previous method. Results demonstrate significant improvements over previous results at frequencies below 1.0 Hz.
Calibration and characterization of the response of infrasound sensors to environmental factors
Authors: Talmadge Carrick L.
Published: November 2013

An infrasound calibration system has been developed at the National Center for Physical Acoustics. The calibration tank is comprised of a 1 in. cylindrical shell 40-in. in diameter, 40-in. long, with 40 in. hemispherical end caps. The interior volume of the tank is approximately 1.8 cubic meters. Up to eight normal-sized infrasound sensors can be enclosed in the volume for one measurement session. Pressure and temperature in the interior and exterior of the tank are also monitored. The pressure source is a 10-in. driver, which is calibrated using multiple barometers that are placed internal to the tank. The measurement paradigm is to drive the tank at a constant amplitude (typically 10-Pa peak-to-peak) and known frequency (typically 0.5 Hz), and to track the variation in the measured response of the test sensor with respect to multiple reference sensors in order to characterize the effect of manipulation of the environment (static pressure, temperature, and seismic motion) on the test sensor. For sensors with very low nonlinearity, allowing the static pressure to change while the driving amplitude of the speaker was held constant was found to be necessary for assessing the effect of nonlinearity on these sensors. Variations in sensitivity on the order of 50 ppm can be measured in a 10-s interval.
Direct measurement of acoustic impedance for wind-noise-reduction pipe systems and components
Authors: Smith Chad M. , Gabrielson Thomas B.
Published: November 2013

A wind-noise-reduction pipe system can have a significant effect on the frequency response of an infrasound array element especially above a few tenths of a hertz. If there is a defect in the pipe system—a clogged resonance suppressor, a blocked or broken pipe, or a flooded manifold, for example—measurement of the frequency response may indicate the presence of the defect but not necessarily the type or location. Direct measurement of the acoustical impedance made at accessible points in the pipe system may be a useful adjunct to in-situ response measurement for identification of the type and location of defects, which may expedite repair especially if most of the system is buried. A prototype of a portable impedance instrument has been constructed and tested both in the lab and under field conditions. Measurements of individual pipe-system components—inlets, pipes, manifolds, resonance suppressors, or gravel piles—are shown along with comparison to theoretical predictions. In addition, defects are intentionally introduced in a rosette pipe system to determine the sensitivity of the acoustical impedance measurement to such defects.
Selective attention and auditory filters
Authors: Schlauch Robert S.
Published: November 2013

Erv Hafter has made significant contributions to our understanding of role of selective attention in detection tasks. I was fortunate to learn from and collaborate with Professor Hafter and his students on some projects addressing this topic as a post-doctoral fellow in his laboratory. We used the probe-signal method to measure auditory filters to learn about the allocation of listening bands under various cuing conditions. Our experiments demonstrated that auditory filters are under a listener’s cognitive control. Our results also helped to explain why large losses are not observed in simple, tonal frequency uncertainty experiments. In Schlauch and Hafter (1991), an analysis of filter widths as the number of cue tones (monitored bands) increased supported an earlier finding by Hafter and Kaplan (1976) that auditory filters widen as the cost of shared attention increases. More recently, in a study inspired by my time in Hafter’s lab, I completed an informational masking experiment that revealed individual differences in the liability of auditory filters that explains the poor performance of some persons in an informational masking task.