bluuebunny/crossref_metadata_2025 huggingface dataset:
Properties of the Umov vector in shallow water and its dependence on sea surface conditions
Authors: Dall'Osto David R. , Dahl Peter H.
Published: November 2013

In this work, the effects of a rough sea surface on shallow water acoustic propagation are examined using experimental data collected during the ONR sponsored Target and Reverberation Experiment (TREX) off of the coast of Panama City, Florida, in May 2013. The acoustic data were collected from a bottom deployed recording tower that coherently recorded data on a horizontal line array (HLA), a vertical line array (VLA), and on an accelerometer-based vector sensor which was combined with a co-located hydrophone to formulate the Umov vector, or instantaneous intensity vector. The source was lowered from the stern of a research vessel to a depth one-third and two-thirds of the water depth (18 m), and transmitted a multi-frequency pulse from 1 to 4 kHz. These measurements were repeated at positions approximately 10, 20, and 40 water depths away from the tower, along a bearing perpendicular and parallel to the surface wave-crests. During the experiment, the sea surface directional-wave spectrum was measured by a Datawell Waverider buoy moored at the experimental site. Properties of the Umov vector are shown to relate to roughness and directional characteristics of the sea surface. The Umov vector is also studied in relation to the HLA and VLA measurements.
Three-dimensional primary acoustic field characterization for a seismic airgun array
Authors: Tashmukhambetov Arslan M. , Ioup George E. , Ioup Juliette W. , Sidorovskaia Natalia A. , Newcomb Joal J. , Stephens James M. , Rayborn Grayson H. , Summerfield Phil
Published: November 2013

The Littoral Acoustic Demonstration Center conducted the Source Characterization Study in 2007 (SCS07) to measure the 3-D acoustic field of a seismic airgun array in the Gulf of Mexico. Three moorings with sensitive and desensitized hydrophones at different depths were deployed as well as hydrophones suspended from a ship, while a seismic source vessel shot specified lines. Hydrophone positions were measured. Peak pressures, RMS sound pressure levels (SPL), sound exposure levels, total shot energy spectra, one-third octave band analyses, and source directivity studies are used to characterize the field. Summary results are first calculated for each hydrophone. These are then combined to give isopleths for azimuthal cuts at 0, 45, 90 degrees, etc., for the spatial domain measures. Plots for each solid angle bin give these and frequency measures analyzed versus range. Zero-to-peak pressures directly under the array go from 210 dB for depths less than 200 m down to 195 dB at 1200 m. At 2000 m horizontal range the pressures go from 160 dB near the surface to 175 to 180 dB at 1200 m. RMS SPL is about 5 dB smaller. [Research supported by the Joint Industry Programme through the International Association of Oil and Gas Producers.]
Estimation of level-crossing rate of signals reflected by ocean surface based on rough surface scattering theory
Authors: Kim Joonsuk , Koh Il-Suek , Lee Yongshik
Published: November 2013

A method is proposed for theoretical estimation of the level-crossing rate of the underwater acoustic communication signals that are reflected from the ocean surface. The variation in the reflection coefficient of the moving ocean surface causes the intensities of the received signals to fluctuate. In this work, the reflection coefficient is obtained by modeling the time-varying characteristics of the ocean surface based on rough surface scattering theory. The surface of the ocean is modeled by Gaussian processes that are characterized by ocean spectra such as the Pierson-Moskowitz and Durden-Vesecky spectra. Furthermore, Gaussian random functions with a particular correlation time are incorporated to model the surface that continuously varies over time. Then the standard Periodogram analysis is applied to estimate the autocorrelation function. Finally, the level-crossing rate is calculated with the negative curvature of the autocorrelation function. For verification, comparison of the simulated results with the measured data is provided.
Modeling the generation and propagation of hydrodynamic hull noise near the ocean surface
Authors: Doyle Rob , Seto Mae , Militzer Julio
Published: November 2013

Hydrodynamic hull noise is an important consideration for determining the detection envelope of SONAR domes mounted to surface vessels. In order to model the generation of this noise by a moving ship, a hybrid computational hydro-acoustic modeling methodology has been developed by combining the Lighthill-Curle acoustic analogy with the Numerical Wind Tunnel computational fluid dynamics code. This model has been shown in previous work to significantly over-predict the experimentally observed far field sound of Canadian Forces Auxiliary Vehicle Quest in at-sea acoustic trials. This deficiency is shown to be due in part to neglecting the Lloyd’s Mirror interference effect of the sea surface in the Lighthill-Curle equations. By utilizing a method of images solution to the acoustic analogy to simulate the Lloyd’s Mirror interference, an average sound pressure level improvement of 25 dB was obtained. This solution is compared and contrasted to a model utilizing the Lloyd’s Mirror interference of a simple source, and a normal mode sound propagation model, and is shown to be superior for transmission ranges up to 2 km.
Backscattering spectrum of a solid cylinder next to a horizontal surface when the cylinder’s axis is not horizontal
Authors: Plotnick Daniel , Marston Phillip L. , Espana Aubrey , Williams Kevin L.
Published: November 2013

When a solid cylinder lies proud on horizontal sand sediment there has been progress in understanding the backscattering spectrum as a function of grazing angle and the viewing angle relative to the cylinder’s axis [Williams et al., J. Acoust Soc. Am. 127, 3356-3371 (2010)]. The resulting evolution of the target strength spectrum is sometimes referred to as the “acoustic color” or the “acoustic template.” For cylinders having identical ends and a transducer at a fixed grazing angle relative to the cylinder’s center, viewing the cylinder over a 90 degree range is sufficient for characterizing the template. If the cylinder’s axis has a vertical tilt such that one end is partially buried in the sand, then the symmetry of the template is altered and a 180 degree range is required. Some of the changes in the template can be approximately modeled using a combination of geometrical and physical acoustics. The resulting analysis gives a simple approximation relating certain changes in the template with the vertical tilt of the cylinder. A similar approximation also applies to a metallic cylinder adjacent to a flat free surface and was confirmed in tank experiments. [Work supported by ONR.]
Surface wave shape inversion from forward scattered ocean acoustic data
Authors: Walstead Sean , Deane Grant
Published: November 2013

Prior work has shown that surface wave shape can be determined by analyzing underwater surface reflected acoustic signals in a wave tank. In this talk, forward scattered data from the Surface Processes and Communications Experiment (SPACE08) is analyzed with regard to surface wave shape inversion. Multipath arrivals representing surface, bottom-surface, and surface-bottom paths are distinguishable, implying that knowledge of the surface is known approximately 1/3, 1/2, and 2/3 the distance between source and receiver. Surface scattering losses including out of plane scattering and small scale roughness are numerically simulated and compared to actual ocean data. Methods are proposed for including these loss factors in a forward model of surface scattering that can be correlated with environmental conditions observed at the Martha’s Vineyard Coastal Observatory.
Research on phase generated carrier demodulation algorithm phase drift of fiber-optic hydrophone
Authors: Yu Ge , Fu Jinshan
Published: November 2013

The paper outlines phase generated carrier (PGC) modulation and demodulation principles of interferometric fiber-optic hydrophone. For demodulation error caused by phase drift, the paper proposes a simple and practical method, using the cross-correlation between the measured signal and the two reference signals to lock the small signal of desired frequency and measure it. Two reference signals with a constant phase difference can directly output the phase of the measured signal. The paper realizes a real-time PGC demodulation system based on Labview with sampling frequency 200 kHz and demodulates 400 Hz underwater acoustic signals. The experiment results show that this system can guarantee the interferometer to operate sensitively. The effectiveness and robustness of the proposed method is demonstrated via this experiment.
Architectural acoustics continuing education course—Presenter registration and reporting requirements
Authors: Brooks Bennett M.
Published: November 2013

The Technical Committee on Architectural Acoustics (TCAA) is a Registered Provider in the American Institute of Architects (AIA) Continuing Education System (CES). The TCAA has developed a standardized introductory short course for architects called “Architectural Acoustics,” for which attendees can earn one continuing education unit (CEU). This paper will cover the administrative requirements of the AIA/CES, to prepare potential presenters. These requirements include the proper handling of paperwork so that AIA members may receive credit for the course. The manner in which the course is given is also dictated by AIA requirements. TCAA membership and attendance at this workshop are required to qualify as an authorized presenter for this AIA/CES short course. Of course, anyone is free to register with the AIA to provide their own CEU program. However, the advantages of participating in this program are that the TCAA short course is already prepared, it is pre-approved by the AIA, and the registration fees are paid by the Acoustical Society of America.
The role of saccular resonance in fish audition
Authors: Hastings Mardi C. , Rozin Rachel
Published: November 2013

Dynamic characteristics and resonance of the saccule play a fundamental role in audition in all teleosts, including those with direct connections between the swim bladder and inner ear. The saccule is an accelerometer with its rigid mass, the otolith (or saggita), coupled to the sensory epithelium through mechanical impedances of the otolithic membrane and hair-cell ciliary bundles. Relative displacement between the saggita and sensory epithelium induced by sound correlates with hearing sensitivity. Dynamic models of the peripheral auditory system in fishes from five different orders (the oscar, broad whitefish, oyster toadfish, dab, and goldfish) were developed for a comparative analysis. Species selected included one without a swim bladder and one with Weberian apparatus that transmits swim bladder motion directly to the saccule. Results for all fishes agreed with audiograms published in the literature. The lowest frequency marking the band of best sensitivity was found to be at the saccular resonance in all species; however, width of the band depended on excitation of the saccule indirectly from motion of the swim bladder and/or Weberian apparatus. Species with swim bladders and larger saggita had best sensitivities at lower frequencies, but with smaller bandwidths because the saccule could not respond to indirect stimulation.
Auditory steady-state response measurement of the temporal dynamics of hearing sensitivity in an echolocating bottlenose dolphin (Tursiops truncatus)
Authors: Mulsow Jason , Finneran James J. , Houser Dorian S.
Published: November 2013

Studies with some echolocating odontocetes demonstrate that receiver-based automatic gain control (AGC) compensates for reductions in echo strength resulting from acoustic spreading loss. This study examined AGC in an echolocating bottlenose dolphin by measuring changes in hearing sensitivity over time courses corresponding to single click-echo pairs. The electrophysiological auditory steady-state response (ASSR) elicited by a 113-kHz sinusoidally amplitude-modulated tone was recorded while the dolphin performed a target discrimination task. Auditory electrophysiological responses were extracted from the instantaneous electroencephalogram and coherently averaged using the modulation rate of the 113-kHz tone as a reference. A Fourier transform was then performed with a 10-ms sliding window to obtain the ASSR amplitude as a function of time relative to the dolphin’s outgoing click and received echo. The ASSR amplitude initially decreased at the time of click emission and then recovered over a course of 25 to 70 ms, depending on target range. This relatively long time course of recovery appears to be consistent with forward-masking, as opposed to an AGC mechanism based on the contraction and gradual release of middle ear muscles coincident with click emission. [Work funded by SSC Pacific Naval Innovative Science and Engineering (NISE) program.]
A technique for measuring bone density using an ultrasonic imaging system
Authors: Miller Catherine J. , Smathers Morgan R. , Thurston Cameron R. , Hoffmeister Brent K.
Published: November 2013

Introduction: Osteoporosis is a degenerative bone disease that affects millions of Americans. Osteoporosis causes normally porous bone tissue, called cancellous bone, to become more porous and weak. It is possible that ultrasonic imaging systems may be used to detect changes in bone density (porosity) caused by osteoporosis. Methods: Ultrasonic images were acquired from 25 cube shaped specimens of cancellous bone in a water tank using a Terason 2000 + ultrasonic imaging system with a 5 MHz linear array transducer. Images were analyzed using an image processing program called ImageJ. Pixel brightness values were plotted as a function of depth in the images of each bone specimen. Pixel value gradient (PVG) was defined as the slope of the resulting graph. Results: PVG was negative for all specimens, and was found to decrease (become more negative) with bone density. PVG demonstrated a moderate but highly significant (p < 0.001) linear correlation with bone density (R = -0.79). Conclusion: Ultrasonic images of bone may be analyzed in ways that yield quantitative information about bone density.
A comprehensive computational model of sound transmission through the porcine lung
Authors: Peng Ying , Dai Zoujun , Henry Brian , Mansy Hansen , Royston Thomas
Published: November 2013

A comprehensive computational simulation model of sound transmission through the porcine airways and lung is introduced and experimentally evaluated. This “subject-specific” model utilizes parenchymal and major airway geometry derived from x-ray CT images. The lung parenchyma is modeled as a poroviscoelastic material using Biot theory. A finite element (FE) mesh of the lung that includes airway detail is created, and COMSOL FE software is used to simulate the vibroacoustic response of the lung to sound input at the trachea. The FE model is validated by comparing simulation results with experimental measurements using scanning laser Doppler vibrometry on the surface of an excised and preserved lung. The FE model is also used to calculate and visualize vibroacoustic pressure and motion inside the lung and its airways caused by the acoustic input. The effect of diffuse lung fibrosis and a tumor on the lung acoustic response is simulated and visualized using the FE simulation. In the future, this type of visualization can be compared and matched with experimentally-obtained elastographic images in order to better quantify lung material properties. [Work supported by NIH Grant EB012142.]
Errors in ultrasonic scatterer size estimates due to mixed scatterer populations
Authors: Gerig Anthony L. , Swan Breanna P.
Published: November 2013

Ultrasonic scatterer size estimation provides an accurate measure of actual scatterer size when those sizes are narrowly distributed about a single, mean value. Although often the case, there are instances in tissue where two or more scatterer types with significantly different sizes are believed to contribute to the same signal. The purpose of this work is to characterize the errors in the size estimates obtained for one scatterer type when contaminating scatterers of a second type are present. Theoretical results for the error are compared with simulation and experimental results for uniform phantoms containing a binary mixture of scatterers. These results indicate that errors can be significant for the frequency bands typically used in size estimation, especially when contaminant scatterers are larger than the scatterers of interest. Results also indicate that, however, these errors can be reduced by shifting the frequency band used to estimate size. A technique for correcting the errors is also described and applied to the phantom data. Although effective, the method requires prior knowledge of the backscatter coefficient of the contaminant scatterers, and the variability of the corrected values can limit its utility as contaminant scattering strength increases.
The performance enhancement of a micro-machined microphone based on field-effect-transistor and electrets
Authors: Shin Kumjae , Je Yub , Lee Haksue , West James E. , Moon Wonkyu
Published: November 2013

Most microphones use a capacitive type transduction. However, this form of transduction faces problems with microminiaturization. The most prominent issue is a decrease in sensitivity at low frequency. Although several works suggested a microphone based on the field-effect-transistor (FET) to solve this problem, other issues, such as low signal to noise ratio and a need for high bias voltage due to metal electrode, remained. To overcome this limit, a micro-machined microphone based on the FET and electret was proposed, and its feasibility was shown in 2012. Its principle is that the electric field arising from the electret controls the channel of the FET embedded on the membrane. Although its feasibility as an acoustic-sensitive device was shown, several problems still exist in terms of stability, sensitivity, and noise. To realize stable and highly sensitive modulation, parametric analysis for the transduction was done to enhance performance. In particular, the surface potential of the electret was increased more than the previous one. It resulted in a stronger electric field applied at the gate. Therefore, it made the FET more sensitive to membrane vibration. The sensitivity evaluation setup was modified for a more accurate measurement. The evaluation results are to be presented.
Experimental comparison of 3-3 and 3-1 mode piezoelectric microelectromechanical systems
Authors: Kim Donghwan , Hewa-Kasakarage Nishshanka N. , Kuntzman Michael L. , Hall Neal A.
Published: November 2013

A common architecture for piezoelectric MEMS sensors and actuators is a thin piezoelectric film patterned atop a much thicker passive bending structure (e.g., a silicon beam or plate). In a first common configuration, parallel plate electrodes reside above and below the piezoelectric film to realize a 3-1 mode device. In a second configuration, a top electrode is patterned in the form of an interdigitated transducer (IDT) to realize a parallel network of 3-3 mode cells. A theoretical comparison of figures-of-merit for each configuration has been presented by research teams in the past. Figures-of-merit include coupling coefficient, actuator strength, and signal to noise ratio for sensing applications. Less work has been performed directly comparing these configurations experimentally using micro-processed thin films. In this presentation, a micromachined accelerometer structure employing a set of multiple springs is used to experimentally compare the two configurations. Each silicon spring contains a 1micron thick lead zicronate titanate (PZT) film along the top surface. Aside from electrode type, the springs are identical in dimension—providing an opportunity for direct comparison.
Time-frequency analysis for acoustics education and for listening to whales in the Gulf of Mexico
Authors: Ioup Juliette W.
Published: November 2013

Time-frequency plots continue to be used in many varied applications. One particularly advantageous use is in acoustics courses accessible to non-science majors, students who are often frightened of mathematics and/or physics. All musicians as well as many others can read and understand music scores (time-frequency plots). Time-frequency plots are extremely useful in explaining the differences in timbre of the same pitch coming from different musical instrument families, from individual instruments themselves, and from different human voices. Examples are given from the first of a UNO two-semester sequence on the Physics of Music (textbook by Rossing!). The second semester of this sequence includes recording and reproduction of music, and time-frequency plots are again very useful. Investigation of acoustic signals for research also benefits from the use of time-frequency plots. The study of marine mammals is enhanced by analysis of underwater acoustic recordings. Examples of both the sounds of and the time-frequency plots for sperm whale clicks in the northern Gulf of Mexico are presented. Seismic airgun shots from oil industry exploration can be heard on the recordings as well as the whale clicks.
Single beam acoustic tweezer
Authors: Shung K. K.
Published: November 2013

Single beam acoustic tweezer, a distant cousin of optical tweezer, has been recently experimentally validated. A prerequisite of acoustic tweezer as in optical tweezer is a sharply focused beam with a steep intensity variation within the dimension of a particle. As the frequency of an acoustic beam reaches 100 MHz or higher, the beam diameter approaches cellular level allowing acoustic tweezing or trapping of a cell. Recent experimental results have shown that at 200 MHz it is possible to trap particles as small as 1 μm and red blood cells (RBC). These results along with the experimental arrangement and potential biomedical applications of acoustic tweezer including measuring RBC deformability will be discussed in detail in this talk.
Hot topics in musical acoustics applied to real-time sound synthesis
Authors: Smith Julius O.
Published: November 2013

(Invited paper for an Interdisciplinary session) New activities in any field are often precipitated by new enabling technologies. In musical acoustics applied to real-time sound synthesis, one exciting new development is smart-phones and tablets having high audio quality, multicore processing power, and display screens with multitouch controls. For example, it is possible to implement a complete virtual-acoustic guitar on current smart-phones and tablets, playable in real time, with plenty of processing power left over for real-time display of chord charts and vibrating-string graphics. (See presentations of the moForte Guitar at this conference and/or on the Web.) A second enabling technology area is evolving high-level domain-specific languages for audio signal processing such as Functional AUdio STream (FAUST). For example, the source code for the moForte virtual acoustic guitar, written in the FAUST language, is about an order of magnitude smaller (and faster to write) than conventional C + +, while the compiled performance is generally within a factor of 2. A third enabling technology area is advancement in methods for convex optimization along with advances in the development of convex formulations of important problems. For example, a convex formulation has recently been developed for approximating 2D bowed-string bridge admittances as ”passive” (positive-real) digital filters. (See presentations by Esteban Maestre.)
Supporting dynamic infrastructure loads from a vibrating structure
Authors: Salter Alexander
Published: November 2013

A large ballroom at a downtown hotel in San Francisco sits directly below the parking garage with ramps located both under and over the Ballroom’s parlor areas on either side. In 2011 Charles Salter Associates, Inc., together with the project architect and structural engineer, developed an isolated structural grid to support the ballroom infrastructure. The grid also allows for variable loading at select rigging points to accommodate a wide range of events. Prior to the renovation, significant vibration and structure borne noise was generated inside the ballroom due to vehicular activities. The ceiling structure, ductwork, and piping, as well as the chandeliers visibly shook and rattled during vehicle pass-bys. As a result, the hotel received complaints and needed to mitigate the issue in order to provide a first class ballroom facility. This paper discusses the background and design process taken in order to mitigate the issue, and describes how the isolated grid provides both acoustical mitigation as well as utility to users of the hotel’s ballroom.
Infrasonic emissions from aircraft wake vortices: Experimental results
Authors: Zuckerwar Allan J. , Shams Qamar , Knight Howard K.
Published: November 2013

Infrasonic emissions from aircraft wake vortices were investigated at the Newport News-Williamsburg International Airport early in the year 2013. Signals received by the microphones situated along an airport runway were processed in 10-s intervals. As an aircraft accelerates toward takeoff, it produces a large pressure burst as it passes each microphone. Following the burst, there appear low-frequency signals of high coherence among microphone pairs. These are interpreted as emissions from the aircraft wake vortices, as suggested by theory. In successive 10-s intervals, the coherence gradually diminishes to background levels, signifying the disappearance of the vortices. On landing the intervals of high coherence precede the bursts at aircraft touchdown, and then diminish. The pressure burst serves as a time stamp for the ensuing vortex emissions and thereby permits the tracking of successive takeoff or landing events on the same runway or on adjacent runways. The emission spectrum is essentially broadband, lacking spectral features (e.g., tones). Data were taken for takeoff of Airbus 319, DC-9, MD-88, CRJ, Lear Jet, Corporate Jet, and Dash-8 aircraft, and for landing of the Airbus 319. The pattern of pressure burst, high-coherence intervals, and diminishing-coherence intervals was observed for all takeoff and landing events without exception.
Backscattering and attenuation mechanisms in solids and solid-liquid suspensions
Authors: Panetta Paul
Published: November 2013

The ultrasonic backscattering and attenuation are commonly used to characterize the properties of solids and solid-liquid suspension to determine grain morphology for solids and particle size and solids loading for solid liquid suspensions. An ultrasonic field is attenuated by absorption and scattering mechanisms as the field traverses a material. However, the relative strength of the absorption, single scattering and multiple scattering contributions are often unknown. In solids, the grain morphology and the dislocation properties are especially important contributions, and in solid-liquid suspension, the particle size and concentration control the attenuation. This paper will present a study of the attenuation mechanisms in solids and solid-liquid suspensions utilizing traditional attenuation, backscattering, and resonance or diffuse field measurements of the attenuation. The results provide the potential to separate the multiple scattering, single scattering, and absorption contribution to the various ultrasonic attenuation measurements on stainless steel alloys and solid liquid suspension. Results for solids and solid-liquid suspensions which elucidate the interrelationship between these energy loss mechanisms will be reported. Where appropriate, the experimental measurements will be compared with theoretical predictions.
Design and implementation of a passive acoustic bedload monitoring surrogate system
Authors: Goodwiller Bradley , Chambers James , Carpenter Wayne , Wren Daniel , Kuhnle Roger , Rigby Jr. , Hilldale Robert
Published: November 2013

Various methods of employing passive acoustics to monitor bedload transport by listening to noise generated by colliding gravel have been explored in both the lab and field. Expanding upon this research, a hydrophone-based passive bedload-monitoring system was designed, tested, and deployed by researchers at the University of Mississippi and the National Sedimentation Laboratory in Oxford, MS. A series of laboratory experiments was used to measure the dependence of acoustic propagation on various parameters such as depth of the water and placement of the hydrophones. These tests employed a calibrated acoustic transmitter to broadcast tones of various frequencies across a gravel bed. Additional flume tests used a motorized carrier to drag rocks across the gravel bed, allowing a known sediment flux to be measured acoustically without any flow noise. The hydrophone-based system was deployed on the Trinity River, Weaverville, CA, in the summer of 2012 and the Elwha River, Port Angeles, WA, in the summer of 2013. Both deployments were co-incident with physical bedload measurements taken by Graham Mathews and Associates. The design of the acoustic system, methods used to analyze the data, results from laboratory experiments, and preliminary results from field data collection will be presented.
Measurement and modeling of pulsed bi-frequency, nonlinear acoustic excitation of buried landmines
Authors: Copenhaver Benjamin J. , Gorhum Justin D. , Slack Charles M. , Barlett Martin L. , Muir Thomas G. , Hamilton Mark F.
Published: November 2013

To help resolve certain practical issues with acoustical methods for humanitarian landmine detection, we have researched using a pulsed, standoff source method for acoustical excitation of the buried mine [J. Acoust. Soc. Am. 130, 2541 (2011); J. Acoust. Soc. Am. 133, 3457 (2013)]. Pulses consisting of two primary frequencies are used in order to search for induced nonlinear vibrations at interaction frequencies such as the sum frequency, which arise due to nonlinear interaction at the mine/soil interface. To model the pulsed excitation, we employ a fully nonlinear time-domain implementation of the lumped-element model of nonlinear soil/mine interaction introduced by Donskoy et al. [J. Acoust. Soc. Am. 117, 690 (2005)]. Modeling is compared with experimental results, which are obtained with bi-frequency pulses exciting a soil with a buried landmine replica, instrumented with a geophone and a nearby microphone. Cases investigated include: (1) target only, (2) buried target under disturbed soil, (3) disturbed soil only, and (4) undisturbed soil. Excitation both on and off the resonance of the buried mine is also investigated, as is burial in different soil types at various depths. [Work supported by the ARL:UT McKinney Fellowship in Acoustics.]
Relationship between internal damping and modal shapes due to fracture growth
Authors: Villalobos Jose , Ledezma Diego , Hinojosa Moises
Published: November 2013

It is shown in this work that the modal shapes and internal damping of simple structures such as bars change when a crack is present in the system, due to geometry changes. The amount of change in damping could be related to crack propagation and detected with traditional damping measurement techniques. Several amorphous materials, metals, and ceramics are subjected to a crack with controlled propagation and their internal damping is measured with modal analysis techniques. It is shown there is a potential application of modal analysis techniques for crack detection in simple geometries.
Predictions from"speech banana"and audiograms: Assessment of hearing deficits in Thai hearing loss patients
Authors: Klangpornkun Nittayapa , Onsuwan Chutamanee , Tantibundhit Charturong , Pitathawatchai Pittayapon
Published: November 2013

“Speech banana” is a banana-shaped plot of speech power distribution, where the abscissa and ordinate represent frequency and intensity. By superimposing speech banana over an audiogram, tested with pure tones, degrees of gain or loss of individual speech sound could be predicted. Speech banana has been constructed for English (Northern and Downs, 1984) and Swedish (Liden and Fant, 1954); however, none has been proposed for tonal languages, such as Thai. This work presents a construction of speech banana for Thai, a language with 21 consonants and 5 lexical tones. Specifically, intensity of each phoneme in the speech banana was calculated by differences of sound pressure level between the local maxima of power spectral density and equal loudness contour at 0 dB. Distribution of the 21 consonants is around 170-5700 Hz and 25-65 dB. Predictions of gain or loss of the phonemes from the constructed speech banana and audiograms were evaluated based on perception test results from seven Thai sensori-neural hearing loss patients, where they identified what they heard from a pair of rhyming words (210 stimuli) differing in initial phonemes, equally distributed across phonemes. Interestingly, the results showed high prediction rates of 71.4-85.7% for phonemes predominantly emphasized on frequency below 2000 Hz.
Communicative intent and affect in mothers’ speech to hearing-impaired infants with cochlear implants
Authors: Kondaurova Maria V. , Bergeson Tonya R. , Kitamura Christine
Published: November 2013

Emotional properties of infant-directed speech influence normal-hearing (NH) infants’ attention to speech sounds. The current study examines communicative intent/affect in speech to hearing-impaired (HI) infants following the first year of cochlear implantation. Mothers of HI infants (HI group, ages 13.3—25.5 months), NH age-matched infants (NH-AM group, ages 13.5—25.7 months) and NH experience-matched infants (NH-EM group, ages 2.3—3.6 months) were recorded playing with their infants at three sessions over the course of one year. 25-second speech samples were low-pass filtered, leaving pitch but not speech information intact. Twelve adults rated stimuli along five scales of communicative intent/affect: Positive/Negative Affect, Intention to Express Affection, Encourage Attention, Comfort/Sooth and Direct Behavior. ANOVAs demonstrated main effects of Group and/or Session for all scales (ps = 0.01 to 0.07). Speech to HI and NH-EM infants was more positive, affective, encouraging, and comforting than speech to NH-AM infants. Mothers decreased affective (NH-EM group) and comforting (HI group) speech qualities over three sessions but increased directive behavior (NH-EM group). The results suggest that affective properties are modified in speech to HI infants depending on their hearing experience rather than chronological age. Mothers adjust these properties to their infant’s developmental stage over the 12-month period.
Ping-pong: Using smartphones to measure distances and relative positions
Authors: Herrera Jorge , Kim Hyung-Suk
Published: November 2013

A novel system for real-time range and geometry estimation of a group of smartphones co-located in a shared physical space is presented. The system uses off-the-shelf devices and employs audible signals to estimate inter-device (pair-wise) distances. Coordinated sound synthesis and processing of a pair of pitched sounds allows to estimate the distance between two devices based on the travel time. By independently analyzing different harmonics of the sounds used in the measurement, a more robust and precise distance estimation is achieved. To overcome the absence of a centralized clock to coordinate measurements, a synchronous communication channel was used. When four or more devices are present, it is possible to estimate their relative positions in a three-dimensional space, by minimizing an equation error norm. The system works both on closed and open spaces. We believe that such system opens the possibility for new ways of interaction that could benefit musical expression, social interaction and gaming.
SpeakerLab: A mobile app for measuring loudspeaker parameters and modeling enclosures
Authors: Jensen Zachary , Bodon K. J.
Published: November 2013

Thiele-Small parameters for loudspeaker drivers are essential in modern loudspeaker design. While they are typically given in specifications by a driver manufacturer, their values can vary considerably. SpeakerLab is a loudspeaker parameter measurement and modeling tool, an all-inclusive app for the loudspeaker designer. Using a specially designed cable with a known impedance, a user will be able to plug their mobile device directly into a loudspeaker driver and measure its Thiele-Small parameters using the added mass or known volume method. With the correctly measured parameters, an enclosure can be appropriately modeled and optimized.
Construction defect actions in residential construction in California after passage of senate bill 800
Authors: Daroux Pablo A. , Wilkens Terry
Published: November 2013

Construction defects actions (lawsuits) involving the sale of new residences that are sold on or after January 1, 2003, are governed by California Civil Code Section 986, also commonly referred to as “SB800” or the “Builder’s Right to Repair Law.” This legislation has redefined the rights and responsibilities of purchasers, sellers, builders, and designers regarding construction deficiencies in significant ways. This presentation will discuss the details of this Legislation as it affects the work of Consultants as Designers and as Forensic Experts.
Overcoming flooring impact isolation performance failures due to adjacent condominium ceiling deficiencies
Authors: Hale Marlund E.
Published: November 2013

There is an increasing demand to renovate apartments and condominiums by installing hard-surfaced flooring. It has become typical for a homeowner’s association (HOA) to enact regulations requiring that upper level dwelling units making flooring upgrades from soft-surface flooring to hard-surface flooring meet specific minimum field impact insulation class (FIIC) or impact sound rating (ISR) performance standards. It is common for these HOA requirements to apply only to the party making the flooring surface change. It is rare that the adjacent ceiling condition or ceiling renovation is addressed by such HOA requirements. This paper presents field performance test results for several renovated condominiums in different multi-family residential buildings that failed homeowner’s association impact performance requirements due to lower-level ceiling deficiencies. Examples of such failures are discussed and successful custom remedies are presented, some of which avoided threatened litigation.
The soundscape experienced by the Southern White rhinoceros (Ceratotherium simum simum) at a wildlife park conservation center
Authors: Wiseman Suzi , Wilson Preston S.
Published: November 2013

Many creatures, including the myopic rhinoceros, depend on hearing and smell even more than on their sight. Noise impacts human health and reproduction, and may impact these other mammals similarly, or even more. Rhinos have been recorded vocalizing infrasonically and sonically. They have a poor breeding record in urban zoos, in which infrasonic noise tends to be chronic. Herd size and composition, the age of potential mates, substrate, enclosure design, and other factors have been studied but little attention if any has been paid to soundscape. As a first step to comparing the soundscapes of facilities in which rhinos have and have not bred successfully, this project recorded and analyzed the soundscape of white rhinos at Fossil Rim Wildlife Center in Texas, one of five Conservation Centers for Species Survival, and one of the few U.S. facilities to successfully breed this species in recent years. Animal responses to sound have been shown to depend on sound level, rate of onset, duration, number of events, spectral distribution of the sound energy, presence of pure tones, the relative level of background noise, and semantics. Similar parameters were analyzed for the data recorded at Fossil Rim and will be presented here.
An automatic single station multipath ranging technique for 20 Hz fin whale calls: Applications for ocean bottom seismometer data in the northeast Pacific
Authors: Weirathmueller Michelle , Wilcock William S. D.
Published: November 2013

Ocean bottom seismometers (OBSs) deployed to monitor earthquakes also record 20 Hz fin whale vocalizations. Because OBSs are often deployed too far apart to record a call on more than one instrument, and call detections are dependent on the acoustic environment, techniques are required to determine call density from a single instrument. One approach is to use point transect distance sampling, which relies on estimates of horizontal range to each call. An automated technique has been developed to estimate range based on the amplitude and relative timing of multipath arrivals assuming a uniform water depth. The method has been evaluated using independently located calls recorded by a seismic network on the Endeavour Segment of the Juan de Fuca Ridge, a region of rough and partially sedimented seafloor. Results suggest that the method works well to ranges of ~5 km but at larger ranges ambiguities arise. Calls at >10 km range are sometimes located between 5 and 10 km because the times are erroneously fit by one too few water column multiples and the amplitudes have too much scatter to be diagnostic of range. The technique is presently being applied in different acoustic settings to determine whether it is more reliable in flat sedimented regions.
Locating invertebrate sound sources, including hermit crabs, on shallow water reefs in the Northwestern Hawaiian Islands using an L-shaped array of hydrophones
Authors: Freeman Simon E. , Freeman Lauren A. , Lammers Marc O. , Buckingham Michael J.
Published: November 2013

Using ambient noise for extracting ecological information from coastal waters is a tantalizing idea that has gained momentum with the increasing use of long-term passive recorders. Single-element hydrophone recordings from different reef locations reveal substantial variation in the biologically produced sound field, the spatial scales and sources of which are poorly understood. A seven-element L-shaped array was deployed in a spur-and-groove coral reef environment at Kure Atoll in the Papahanaumokuakea Marine National Monument, Northwestern Hawaiian Islands, in an effort to resolve small-scale spatial variability in reef-generated ambient noise. For each given time step, a fast, pair-wise coherence technique was initially used to estimate correlation in the ambient noise field. Curved-wavefront adaptive beamforming was then performed within range and azimuth windows that encompassed each estimated source location (areas of high correlation). Array processing performance was evaluated and frequency-dependent, spatiotemporal distribution of the sound field derived. The environment surrounding the array was photographically surveyed and ecologically classified through SCUBA-based observations. Survey data were used in an attempt to identify reef structures and the organisms that were the dominant contributors to the local sound field, notably hermit crabs and other hard-shelled invertebrates.
Ocean sensing using ambient noise: An overview
Authors: Sabra Karim G.
Published: November 2013

The random nature of ocean ambient noise, natural or man-made, tends to suggest limited utility: ambient noise is commonly considered to be a nuisance for acoustic sensing or imaging applications. However, whether noise is a nuisance or a useful signal actually depends on how it is processed. Indeed, acoustic fields from random sources are often considered to be incoherent, but there is some coherence between two sensors that receive signals from the same individual noise source. Consequently, by cross-correlating the ambient noise recorded at two hydrophones one can estimate the acoustic waves that propagate between them, thus yielding an estimate of the Green's function between those sensors. This passive approach provides a foundation for ocean sensing and imaging techniques using only ambient noise, thus without active transmitters. We will examine the basic background physics of extracting coherent information from ambient noise. Specifically we will highlight among others the role of frequency/bandwidth, noise structure/distribution, ocean fluctuations, sensor separation and, if employed, the array configuration on this process. Further we will give an overview of recent experimental results in shallow and deep water and discuss practical challenges for implementing noise-based ocean sensing techniques.
Extracting seabed properties using ocean noise measured on an autonomous underwater vehicle mounted array
Authors: Siderius Martin , Nielsen Peter L. , Miller James H.
Published: November 2013

Ocean ambient noise has been used to estimate seabed properties such as bottom loss and bottom layering. These ambient noise methods use beamforming and typically collect data on hydrophone arrays of 16 to 32 sensors that are moored or allowed to drift. Compact arrays containing only a few sensors can be mounted to autonomous underwater vehicles (AUVs). This configuration provides better control over the location of the measurement compared to a drifting system. However, compact arrays of this type present a challenge due to limited beamforming capabilities. In July 2012 and June 2013, the Centre for Marine Research and Experimentation conducted the GLASS’12 and GLASS’13 experiments to investigate the possibility of using an AUV equipped with a compact nose array for seabed characterization. The nose-mounted array consisted of a 5-hydrophone vertical and 4-hydrophone tetrahedral array. In this paper, the results from these experiments will be presented along with approaches to seabed characterization using hydrophone arrays with few sensors.
Models for non-stationary reverberation noise
Authors: Cohen Leon
Published: November 2013

The random phasor approach to reverberation noise gives Gaussian statistics for intensity and is stationary in time and space. We show that fundamentally different things happen when the noise is defined by a superposition of random propagating pulses that have width. We calculate the nonstationary autocorrelation function of such a model and describe how it evolves in time and space in a dispersive medium. Furthermore, we give criteria for when a nonstationary autocorrelation function is locally stationary in time and/or space. We also consider how and under what conditions the noise evolves to the stationary case given by the ransom phasor sum. [Work supported by ONR.]
Challenges in the characterization of high intensity therapeutic ultrasound devices and fields and regulatory guidance development
Authors: Maruvada Subha , Harris Gerald R.
Published: November 2013

As part of its regulatory responsibility for medical devices, the US Food and Drug Administration (FDA), Center for Devices and Radiological Health, reviews pre-clinical and, if necessary, clinical data submitted by device applicants relevant to safety, effectiveness, and accurate labeling. For HITU devices, pre-clinical testing can include ultrasound power measurement, pressure/intensity mapping, temperature field characterization (in vitro and in vivo), acoustic and thermal simulations, and demonstration of the targeting accuracy and treatment monitoring. To assist manufacturers and third parties in the submission process, the FDA provides pre-market submission guidance that often relies on technical standards and specifications such as published by the International Electrotechnical Commission (IEC). IEC documents for HITU are currently nearing completion. However, even with these documents, technical challenges remain because of the focused, large amplitude pressure fields encountered in HITU. Measurement and modeling issues include using radiation force balances at HITU power levels, the need for complex deconvolution with some hydrophone types, validation of simulation models, tissue-mimicking material development for temperature measurements, and cavitation detection and quantification. These challenges along with current FDA guidance efforts will be discussed.