bluuebunny/crossref_metadata_2025 huggingface dataset:
Sixty years of launch vehicle acoustics
Authors: Lubert Caroline P.
Published: November 2017

On 4 October 1957 at 7.28 pm, the first artificial low Earth orbit satellite, Sputnik, was launched by the Soviet Union. Its launch ushered in a host of new scientific and technological developments, and public reaction in the United States led to the so-called “Sputnik Crisis,” and the subsequent creation of NASA. A race ensued between the United States and the Soviet Union to launch satellites using carrier rockets. At this time, very little was known about the acoustics of rocket launches, and even less about acoustic suppression. Thus, in the vicinity of the rocket, acoustic levels could reach up to 200 dB during lift-off. Such extremely high fluctuating acoustic loads were a principal source of structural vibration, and this vibro-acoustic interaction critically affected correct operation of the rocket launch vehicle and its environs, including the vehicle components and supporting structures. It soon became clear that substantial savings in unexpected repairs, operating costs, and system failures could be realized by even relatively small reductions in the rocket launch noise level, and a new discipline was born. This paper presents a review of the first 60 years of launch vehicle acoustics.
Validation of aero-vibro acoustic simulation technique using experimental data of simplified fairing model
Authors: Tsutsumi Seiji , Maruyama Shinichi , Sarae Wataru , Terashima Keita , Hiraiwa Tetsuo , Ishii Tatsuya
Published: November 2017

To predict harmful acoustic loading observed at lift-off of the launch vehicle, aero-vibro acoustic simulation technique is developed. High-fidelity large-eddy simulation with computational aeroacoustics based on the full Euler equations in time domain are employed to predict generation of the acoustic waves and their propagation to the fairing. Coupled vibro-acoustic analysis based on finite element method are applied to compute the transmitted acoustic wave into the fairing both in the time and frequency domains. Acoustic measurement of a simplified fairing model with a subscale liquid rocket engine is conducted, and validation study of the present technique is performed. Reasonable agreement is obtained for peaks of the acoustic spectrum taken inside the fairing model. Such peaks are found to be related to the internal acoustic modes and ring modes of the faring structure. However, further study is required to obtain quantitative agreement.
A review of ASTM International standards relating to impact sound transmission in buildings
Authors: Lilly Jerry G.
Published: November 2017

Impact sound transmission in buildings is an important issue, especially in today's multifamily marketplace where the trend to replace carpet with hard surface flooring is becoming more popular every year. This presentation will discuss the many changes that have been made over the years to the laboratory and field test methods for evaluating impact noise in buildings, including new standards under development.
Non-standard uses of the mechanical tapping machine in field measurements
Authors: Lilly Jerry G.
Published: November 2017

The mechanical tapping machine creates a continuous series of floor impacts which generate a steady-state sound field when measured indoors. Because each individual hammer has the same weight and free-falls from the same distance, the machine creates a calibrated and steady impulsive force into the floor structure. This presentation will illustrate potential future test methods for assessing sound transmission in buildings with examples to evaluate structure-borne sound transmission into structurally isolated anechoic and reverberation rooms.
Machine learning the acoustic impulse response of a rough surface
Authors: Keiffer Richard S. , Dennis Steven
Published: November 2017

Due to time constraints imposed by operational considerations, reverberation models used by the Navy split the computational work by modeling the propagation and the scattering separately. The scattering module is typically a “look-up” table linking the incident sound field at any point on the boundary to a pre-computed statistic of the scattering. There are at least two significant drawbacks to this standard modeling approach. First, each acoustic interaction with the boundary generates a unique realization of a stochastic process, and consequently, no single statistic of the scattering always can be justified and the correct modeling of the statistics of reverberation time series must acknowledge this event-to-event variation. Second, pre-computing the scattering based on an assumed statistical description of the unresolved boundary irregularities without consideration of the resolved boundary irregularities prohibits the coherent inclusion in that scattering calculation of the effects that the resolved boundary irregularities have on the scattering. Machine-learned models for the boundary scattering hold the promise of addressing both of these issues. The purpose of this talk is to explore these issues and the prospect of developing a machine-learned model for the acoustic impulse response of a multi-scale rough ocean boundary. [This work was supported by the U.S. Office of Naval Research.]
Modal analysis of split-step Fourier parabolic equation solutions in the presence of rough surface scattering
Authors: Aslan Mustafa , Smith Kevin B.
Published: November 2017

Determining accurate solutions of acoustic propagation in the presence of rough surface scattering is of significant interest to the research community. As such, there are various approaches to model the effects of rough surface scattering. Typically, the models used assume an idealized pressure release condition at the sea surface boundary. This boundary condition can easily be accommodated through a variety of modeling techniques for flat surfaces, but it is necessary to introduce additional complex methods in numerical models for rough surfaces. Parabolic equation (PE) models utilizing split-step Fourier (SSF) algorithms have been employed to treat the rough surface displacements. These include methods such as the field transformational technique (FFT), and direct modeling of the physical water/air interface discontinuity. Previous work highlighted phase errors in SSF-based models with large density discontinuities at the interfaces, which were minimized by employing a hybrid split-step Fourier/finite-difference approach. However, such phase errors were largely absent in the presence of rough surface scattering. In this work, the PE solutions are decomposed into normal modes in order to determine which modes dominate the phase error in the presence of flat surfaces, and to confirm that these modes are highly scattered in the presence of rough surfaces.
Data analysis and modeling of broadband acoustic propagation perpendicular to internal wave fronts and sand dune crests in the South China Sea
Authors: Reeder D. Benjamin , Chang A. Y. , Chen Chi-Fang , Chiu Ching-Sang , Chiu Linus , Miller Chis , Ramp Steven R. , Wei Ruey-Chang , Yang Y. J.
Published: November 2017

Very large subaqueous sand dunes were discovered on the upper continental slope of the northeastern South China Sea (SCS) in the spring of 2007 during an ONR 322OA-funded field experiment which was designed to study the large transbasin internal solitary waves (ISW) that are generated by tidal forcing in the Luzon Strait. These internal waves and sand dunes are important acoustical features, as it is expected that they will cause significant anomalies in the acoustical field. In the spring of 2014, a broadband source was deployed to transmit 850-1150 Hz LFM signals to receivers on a mooring in the center of the sand dune field. The acoustic transect was oriented perpendicular to the dune crests, ISW fronts and isobaths. Data analysis and extended modeling are presented to quantify the degree to which these features impact the propagation of broadband signals in the 100-2000 Hz band as a function of source depth and frequency.
Measurement of mid-frequency acoustic backscattering from the sandy bottom at 6–24 kHz in the Yellow Sea
Authors: Kan Guangming , Liu Baohua , Yang Zhiguo , Yu Shengqi , Yu Kaiben , Pei Yanliang
Published: November 2017

In a typical sandy bottom area of the South Yellow Sea, measurement of acoustic bottom backscattering strength within a frequency range of 6–24 kHz was conducted using omnidirectional sources and omnidirectional receiving hydrophones. In this experiment, with interference from scattering off the sea surface being avoided and the far-field condition being satisfied, we obtained acoustic bottom backscattering strength values ranging from −31 to −17 dB within a grazing angle range of 18°–80°. In the effective grazing angle range, the acoustic scattering strength generally increases with the increase in the grazing angle, but the variation trends were different in different frequency bands, which reflects different scattering mechanisms. The frequency dependence of the acoustic backscattering strength is characterized by a segmented correlation. In the frequency band of 6–11 kHz, the scattering strength is positively correlated with the frequency, and the average slope of the linear correlation is about 0.83 dB/octave; in the frequency band of 12–24 kHz, the scattering strength generally exhibits a negative correlation with the frequency, and the slope of the linear correlation is about −0.42 dB/octave.
Improving scattering surface design with rapid feedback by integrating parametric models and acoustic simulation
Authors: Shtrepi Louena , Menichelli Jessica , Astolfi Arianna , Mendez Echenagucia Tomas , Masoero Marco C.
Published: November 2017

Acoustic panels need to be optimal for both acoustic performance and aesthetic values, in order to respond to the requirements of both architects and acousticians. However, current practice shows that there is a gap in interaction between these professionals. Hence, new strategies in enhancing the efficiency of the design should be investigated. This study proposes a new design process for diffusive surfaces by integrating parametric models and acoustic simulation, aiming to provide architects with rapid visual and acoustic feedback. The new process consists of three parts: (1) basic geometric guidelines for diffusive surface design, which give the necessary information to architects with no acoustic background; (2) programming a parametric model of a diffusive surface sample in Rhinoceros, which allows for very quick variations in the design and suits the flexibility required by architects’ design practice; (3) connecting Rhinoceros and a simple ray tracing, which adds acoustic simulation functionality and visual output to facilitate architects’ utilization and feedback comprehension. Finally, a characterization of the scattering coefficient is performed in a scale model based on ISO 17497-1 in order to verify the effectiveness of the new design process.
Assessing perceived diffuseness in music venues
Authors: Jeon Jin Yong , Kwak Kee Hyun
Published: November 2017

The effect of diffusing elements on the variance of indoor acoustical quality is defined as “diffuseness,” and the perception of diffuse sounds is mainly affected by the absorption and diffusion coefficients of surface materials in performance spaces. To characterize sound-field diffuseness, the acoustic parameters of a room, along with impulse-based diffusivity indices are calculated from the binaural room impulse responses. Then, auditory experiments are carried out for using convolved sounds, by investigating the acoustical attributes defined for perceived diffuseness: density of reflection, smoothness of decay, smoothness of reflection, and isotropic directivity. Diffuseness normally reduces the bass ratio and increases the brilliance, thereby increasing the clarity but decreasing the sound strength. In addition, the installed diffusers objectively increase envelopment, intimacy, and diffusion perception. It is seen that the direct sound level supported by the amount of diffuse reflections are related to the perception of diffuseness. With regard to the diffuseness for the acoustical preference in a space, the parameter Np, the number of peaks computed for the measured impulse responses, is effective for evaluating the diffuse sound fields influenced by early scattering reflections.
Theoretical model of reverberation decay in a rectangular room—Potential for predicting flutter echo
Authors: Hanyu Toshiki
Published: November 2017

Reverberation is the most important factor governing the acoustic design of a room. It is known that non-exponential reverberation decay may occur in a room with unevenly distributed sound absorption, namely, with non-diffuse sound field. We propose the theoretical model of reverberation decay in non-diffuse sound fields. The reverberation decay is characterized by absorption and scattering properties of the surfaces of a room. As a first step for developing reverberation theory of non-diffuse sound field, the proposed model deals with rectangular rooms, because rectangular rooms are very common in any kind of buildings and architecture. Spatial absorption coefficients for three orthogonal directions are defined as the parameters which characterize the energy decay curve in the rectangular room. Within this model, the reverberation in such rectangular room becomes a combination of exponential and power law decay. The power law dependence as a function of time has a singularity. This issue is resolved within the model. The model was verified by comparison with the results of computer simulation using sound ray tracing method. Theoretical solutions of the proposed model agree well with the results of the computer simulation. Potential for predicting flutter echo by this model is also discussed.
Soundscape fishing: Spatial variability in a low-frequency fish chorus in the southern California kelp forest
Authors: Pagniello Camille M. , Butler Jack , D'Spain Gerald L. , Jaffe Jules , Parnell Ed , Širović Ana
Published: November 2017

The kelp forests off the coast of southern California support a diverse assemblage of fishes, many of which are known to produce sound. Here, the spatial variability of a low-frequency (325–545 Hz) fish chorus recorded at three sites near the kelp forests off La Jolla, California, is described. This chorus dominated the dusk soundscape at all sites in May/June 2015, 2016, and 2017. During these times, spectral levels around 400 Hz increased by approximately 30 dB over a period of 3 h between 19:00 and 22:00 local time. The location of the fish chorus was estimated during each year using beamforming and time difference of arrival (TDOA) techniques on signals recorded by either a two-element 30-m aperture linear seafloor array or an array with four-elements, 20-m aperture in a tetrahedral-shaped configuration. This location was relatively constant during the chorusing each night. Environmental factors such as temperature, macroalgae assemblage and bottom cover, and geological features were investigated as possible drivers of the spatial distribution of the chorus. [Research supported by California Sea Grant (R/HCME-28) and a Natural Sciences and Engineering Research Council of Canada (NSERC) Postgraduate Scholarship-Doctoral (PGS D-3).]
An exploration of rhythm perception in African penguins (Spheniscus demersus)
Authors: Fobe Irene A. , DeLong Caroline M. , Wilcox K. T.
Published: November 2017

Rhythmic properties in penguin vocalizations may be unique to individuals. Rhythm perception is a cognitive ability previously thought to be exclusive to vocal-learning species who have the neurological complexities required to mimic conspecific and heterospecific vocalizations. Discovering rhythm perception in penguins would provide insight on penguins’ ability to recognize kin using auditory cues, and discount theories constraining rhythm perception to vocal-learning animals. The goal of this study was to learn if African penguins (Spheniscus demersus) could perceive changes in rhythm using a habituation-dishabituation paradigm. Subjects were 32–38 African penguins housed at the Seneca Park Zoo in Rochester, NY. Penguins were played four rhythms at 4 kHz and head turns per bird were counted in 24 sessions. Each session was composed of ten familiarization trials followed by six test trials that alternated between the familiar and novel rhythm. The number of head turns per bird did not significantly increase from the last three familiarization trials to the first novel test trial. Results were inconclusive in showing evidence for auditory rhythm perception in penguins. This may be because subjects met the habituation criterion in only 9 out of 24 sessions. More research on auditory rhythm perception in penguins is needed.
Aerodynamic Sound Production from Flying Beetles
Authors: Hayashi Rintaro , Allen John S. , Jenkins Daniel
Published: November 2017

The flapping wings of insects generate sounds during their flight. Recent interdisciplinary studies have extensively investigated the lift and thrust mechanisms produced from flapping flight; however, the associated sounds produced are less understood. Most studies have examined the amplitude and frequency with respect to wing beat reporting on the associated harmonic structure. The directionality and phase relationships have been examined in more detail in a few recent studies for flies and mosquitoes. In this study, we examine the sound generation mechanism from two invasive beetle species to Hawaii which are the Oriental Flower Beetle and the Coconut Rhinoceros Beetle. The wing beat, amplitude, and phase relationships are measured and determined with an eight element spherical microphone array. The mechanism of second harmonic generation for the different species is investigated with adaptive signal processing (Empirical Mode Decomposition) and complementary high speed optical video. The rotational motion of wing has a significant role in the second harmonic for the Coconut Rhinoceros Beetle. The different location and phase oscillation of the elytron for the two species results in different vortex generation during the down stroke.
Long-term, quantitative observations of seafloor hydrothermal venting using an imaging sonar
Authors: Xu Guangyu , Jackson Darrell , Bemis Karen G. , Ivakin Anatoliy
Published: November 2017

While connected to the NEPTUNE observatory operated by Ocean Networks Canada (ONC) at the Endeavour Segment of the Juan de Fuca Ridge (http://www.oceannetworks.ca/observatories/pacific), the Cabled Observatory Vent Imaging Sonar (COVIS) recorded an unprecedented long-term (>4 years) acoustic dataset capturing local hydrothermal venting. Processing of the acoustic backscatter data yields three-dimensional (3-D) images of plumes rising tens of meters from black smoker vents on a sulfide structure named Grotto. More importantly, analysis of the Doppler frequency shift in acoustic backscatter yields estimates of the flow rates of those plumes and their volume fluxes. Subsequent calculations based on the vertical variation in volume flux and a theoretical heat-to-volume-flux relationship for buoyancy-driven plumes give estimates of plume heat flux, which are essential for studying the temporal evolution of a hydrothermal system and its coupling with geological, oceanic, and biological processes. In addition to black-smoker plume observations, the ping-to-ping decorrelation of seafloor backscatter recorded by COVIS provides an acoustic indicator of diffuse-flow (i.e., low- temperature, clear hydrothermal discharge) distribution over Grotto and its surrounding areas. Furthermore, acoustic techniques for quantifying the temperature fluctuations, and ultimately, heat flux of diffuse-flow venting are currently under development. [Work supported by NSF.]
Observing the evolution and fate of free methane in the ocean
Authors: Weber Thomas C. , Weidner Elizabeth F. , Padilla Alexandra M. , Rychert Kevin M. , Loranger Scott
Published: November 2017

Free methane gas is increasingly observed escaping the seabed in the world’s oceans from sources that are either biogenic, typically in shallow sediments, or from deeper geologic reservoirs. Methane gas bubbles undergo a complicated journey as they rise toward the sea surface. Some or all of the methane may pass through the gas-liquid boundary, into aqueous solution, where it is eventually oxidized and can impact ocean chemistry. Some of the methane, particularly in shallow environments, may reach the atmosphere where it acts as a strong greenhouse gas. One of the key questions regarding the transport of methane upward from the seabed is how much goes where, and this question is being increasingly addressed using acoustic remote sensing techniques. Answering this question begins with seep detection and localization, now routinely performed on data collected with split-beam and multibeam echo sounders. Once located, observations of the bubble-plume backscattering cross section can be used to address questions of flux and vertical gas transport. Both narrow- and broad-band techniques and some of the associated challenges, including wobbly bubbles and multiple scattering in dense plumes, will be discussed.
Enhanced subsea leakage detection with broadband active acoustic sensor system
Authors: Pedersen Geir
Published: November 2017

For field re-activation, improved/enhanced oil recovery through injection of gas in reservoirs, and geological storage of CO2 (carbon dioxide), robust barriers must be provided and confirmed to avoid leakage. Natural seeps from the sea floor represents an additional challenge, as many detection systems will misinterpret them as an infrastructure leakage. Active acoustics (backscattering) has been successfully used for detection of even moderate underwater hydrocarbon gas releases at long ranges, using, e.g., scientific echosounders. However, CO2 leakage behavior is particularly complex and operations in cold and deep waters make such leakages difficult to detect with active acoustics, due to its behavior and low acoustic impedance in liquid phase. Methodology for detecting CO2 even in liquid phase is a prerequisite for many deep water operations, and at present no adequate technology exists for this purpose. In order to design an active acoustic system that can detect subsea leakage of hydrocarbons and CO2 in liquid phase, the behavior and backscattering by droplets as a function of environmental parameters and acoustic frequency is simulated. Theoretical backscattering is further compared with in situ acoustic and optical measurements of CO2, CH4 (methane), and air, released and measured at depths from 1300m to surface, using a custom built gas release and measurement frame.
Measurement of speed of sound profile as a function of altitude
Authors: Li Zhuang , Schaefer Brett , Schaefer Brian , Dever William , Morgan Tyler , Foltz Matthew
Published: November 2017

The goal of this undergraduate research project is to design a balloon payload of less than 500 g to measure speed of sound and atmospheric data including temperature, pressure, humidity from 0 to 100,000 feet altitude. The payload is made of polystyrene foam due to its lightweight and good thermal isolation property. An ultrasonic sensor with a reflection mirror are installed outside payload box to measure speed of sound. As the ultrasonic sensor’s working temperature is above −40 °C, a heater is attached to the sensor but isolated from the environment. Temperature, pressure, and humidity sensors were calibrated. Power consumption was also calculated and power is supplied by 2CR5 batteries. Software for the project was developed in Arduino DUE. An SD card shield is connected to the Arduino board for data storage and RTC clock. Tests were conducted in vacuum chamber and freezer prior to flight. Balloon launch was successfully conducted in the NASA CSBF on May 16 2017. Speed of sound was also calculated using measured environmental data. Measured and calculated speed of sound profiles were compared and reasonably agree with each other. An improved payload will launch in Carbondal, IL, on August 21, 2017, during the solar eclipse.
Extension of the phase and amplitude gradient estimator method for acoustic intensity to multiple tones
Authors: Succo Kelli , Sommerfeldt Scott D. , Gee Kent L. , Neilsen Tracianne B.
Published: November 2017

The phase and amplitude gradient estimator (PAGE) method [Thomas etal., J. Acoust. Soc. Am. 137, 3366–3376 (2015)] has proven successful in improving the accuracy of measured energy quantities over the traditional p-p method in several applications. One advantage of the PAGE method is the use of phase unwrapping, which allows for increased measurement bandwidth. However, phase unwrapping works best for broadband sources and fields with high coherence. Narrowband sources often do not have coherent phase information over a sufficient bandwidth for a phase unwrapping algorithm to unwrap properly. Even for narrowband signals, the PAGE method has been shown to provide correct intensity measurements for frequencies up to the spatial Nyquist frequency. This is improved bandwidth over the p-p method. Previous work with sawtooth waves in a plane wave tube shows that in cases with multiple tones, the PAGE method with a few additional steps of processing accurately calculates intensity above the spatial Nyquist frequency provided one tone is below it. A variety of further experiments with multiple tones are explored to determine if any extra steps in processing or ingenuity in data acquisition can reasonably be used to achieve comparable results in a free-field environment. [Work supported by NSF.]
Fluid instabilities in turbocharger compression systems
Authors: Dehner Rick , Selamet Ahmet , Selamet Emel
Published: November 2017

Turbochargers increase the power density of internal combustion engines, which allows the displaced volume to be reduced and the fuel efficiency to be improved for the same level of performance. However, the demand for turbocharger centrifugal compressors to deliver increasingly elevated boost pressures, over a wide air flow range, results in unfavorable flow fields that generate narrow and broadband noises within the engine air induction system. The present study is a combined computational and experimental effort, focusing on identifying unsteady fluid-flow instabilities in a turbocharger compression system installed on a bench top stand. This work concentrates primarily on prediction of mild and deep surge instabilities, since they limit the low-flow operating range. Surge occurs near the Helmholtz resonance frequency of the compression system (including a compressor inlet duct, centrifugal compressor, compressor outlet duct, plenum, plenum outlet duct, and a valve) and results in low frequency pressure fluctuations throughout the compression system. Additionally, the compressor flow field adapts to operation at reduced flow rates by forming rotating instabilities in the impeller inducer and vaneless diffuser, which contribute to the occurrence of surge and produce noise as they interact with the rotating impeller and stationary volute.
High-performance aircraft short-takeoff and vertical-landing noise measurements on an aircraft carrier
Authors: Wall Alan T. , McKinley Richard L. , Aubert Allan C. , Powers Russell W. , Smith Michael J. , Stouffer Charles J. , Ku James C.
Published: November 2017

The noise levels caused by high-performance aircraft are relatively high in the close proximity experienced by crew on board aircraft carriers, which can interfere with communications and may pose a risk for hearing loss. This paper reports on preliminary results of noise measurements of the operations of F-35B aircraft performing short-takeoff and vertical-landing (STOVL) operations on the flight deck of an LHA aircraft carrier. This noise measurement campaign was performed in late 2016, by scientists from the Air Force Research Laboratory (AFRL) in collaboration with the Naval Air Systems Command (NAVAIR) and the F-35 Integrated Task Force (ITF). The measurements were taken using hand-held noise recorder systems, and the recording engineers shadowed actual locations of crew. These data will be used to validate STOVL models of crew noise exposures on deck. [Work supported by F-35 JPO.]
Spatial interpolation of noise monitor levels
Authors: Nykaza Edward T.
Published: November 2017

Continuously recording noise monitoring stations provide feedback of the noise environment at monitor locations. While this feedback is useful, it only provides information at a few point locations, and in many cases it is of interest to know the noise level(s) at the locations between and beyond noise monitoring locations. In this study, we test the accuracy of several spatial interpolation models with experimental data collected during the Strategic Environmental Research and Development Program (SERDP) Community Attitudes Towards Military Blast Noise study. These datasets include 9 months of blast noise events captured at two different study locations. In both cases, a small number of monitors (e.g., 3–9) were located over a large region of interest (e.g., 1–8 km2), thus providing realistic operational conditions. The utility of deterministic (e.g., nearest neighbor, Delaunay triangulation, thin plate splines, etc.) and stochastic (e.g., geostistical or kriging) interpolation models for estimating single-event and cumulative noise levels is examined using leave-one-out cross validation. The accuracy of each approach is assessed with the root-mean-square-error (RMSE), and we discuss the practical implications of implementing such approaches in real-time systems.
Current research thrusts at NCPA
Authors: Gladden Josh R.
Published: November 2017

Over the 30 year history of the National Center for Physical Acoustics, the technologies have advanced and research has evolved; however, the mission has remained the same: to pursue solutions to practical problems using a fundamental physics approach, to educate the next generation of physical acousticians, and to serve as a translational bridge between basic research generated by our academic communities and the private sector. In this talk, I will discuss major research thrusts and accomplishments of NCPA in the last 5–8 years. Topical areas covered will be infrasound and long range propagation, aeroacoustics, structural health monitoring, physical ultrasound, and acoustics in porous media. I'll include some discussion of prominent scientists driving this research along with a few funny stories.
Generalized control metric for active structural acoustic control: A novel understanding for controlling symmetric structures
Authors: Cao Yin , Sun Hongling
Published: November 2017

Active structural acoustic control (ASAC) is a strategy aiming at controlling the radiated sound of the structure by controlling the vibration. Generally, controlling the vibration is not the same as controlling the radiated sound. Therefore, the choice of the control metric also referred to as the cost function in ASAC is a very important research topic and has been received a lot of attentions by researchers. Previous research has identified a novel control metric named the weighted sum of spatial gradients (WSSG). An analysis has shown that WSSG is able to closely approximates the performance of using radiated sound power as the control objective by choosing the right weights. In this paper, based on previous findings, a generalized control metric of active structural acoustic control for symmetric structures is discussed and analyzed. For symmetric structures, the radiated resistance matrix is always bisymmetric. It will be shown that controlling the vibration is able to achieve the performance of directly controlling the radiated sound power provided that the secondary plant matrix is overdetermined. A uniformed control metric for active structural acoustic control of symmetric structures will be presented and analyzed.
Native perception of Cantonese tones in high-variability conditions
Authors: Chen Yan
Published: November 2017

This study investigates how native speakers of Cantonese perceive and produce Cantonese tone pairs T2-T5, T3-T6, T4-T5, T4-T6, and T5-T6 in high-variability conditions. Thirty five native speakers of Cantonese from Hong Kong participated in a 6AFC identification task (screening test), a mixed-talker AXB task (ISI = 1500 ms), and a mixed-talker repetition task (delay = 1500 ms). Results from the screening test showed that the participants did not merge the tones examined in this study. Results from the AXB task showed that (1) perception of tones with f0-height differences (T2-T5 and T3-T6) was more challenging than perception of tones with f0-contour differences (T4-T5, T4-T6, and T5-T6), (2) tones contrasting in direction of f0 change (T4-T5) were the easiest, and (3) perception of level tones (T3-T6) was more difficult than perception of contour tones with an f0-height difference (T2-T5). Data from the repetition task were fitted with quadratic polynomial equations (y = a + bx + cx2) and the analysis revealed that the participants produced the two level tones—T3 and T6—distinctively (in terms of coefficient-a) and the two rising tones—T2 and T5—distinctively (in terms of coefficient-c). This indicates that the participants perceived different level tones and different rising tones in the repetition task (i.e., no tone merger).
Measurement scales, psychophysical models, and reliability statistics in voice quality perception
Authors: Silbert Noah H.
Published: November 2017

Perceptual judgments of voice quality can be given on discrete or continuous scales. Discrete scales are typically described as consisting of “equal appearing intervals,” and continuous judgments may be given on visual analog scales (VAS) or via direct magnitude estimation. Interrater agreement on discrete scales is highly variable and often poor, though there is evidence that application of psychophysical principles (i.e., perceptual variability, response bias) can increase reliability. There is some evidence that interrater reliability may be higher with continuous scales, though the influences of psychophysical assumptions and measurement properties on the reliability of continuous scales has not been analyzed particularly thoroughly. The present work considers the effects of different assumptions about underlying perceptual and decisional processes on the measurement properties and reliability of perceptual voice quality scales. An adaptation of Stevens’ power law combined with different decision rules provide a model of the mapping between the acoustic properties known to influence voice quality (e.g., H1-H2, HNR) and discrete or continuous clinical judgment scales (e.g., “breathiness,” “roughness”). The effects of variation in model parameters on reliability and agreement statistics will be analyzed, and novel agreement statistics based on the properties of ratio-scale judgments will be explored.
Delayed auditory feedback induces slow oscillations in vocal fundamental frequency and intensity
Authors: Lee Jieun , Brajot Francois-Xavier
Published: November 2017

A system with negative feedback tends toward oscillation or instability when delay is introduced into the feedback loop. Given current evidence for feedback control of pitch and loudness, we hypothesized that delaying auditory feedback during sustained phonation would result in oscillations in fundamental frequency and vocal intensity. Subject produced a sustained vowel across seven auditory feedback conditions: 0, 100, 200, 300, 400, 500, 600, and 700 ms delay. Increasingly large oscillations in fundamental frequency and intensity were observed as delay increased. The frequency of oscillations as a function of delay appear to be subject-specific, with a range between 0.3 and 0.8 Hz. These oscillations carried over into the prosodic contour of subjects' connected speech produced under the same delay conditions. These results suggest that disfluencies induced by delayed feedback (e.g., sound prolongations) may be the result of compensation for shifts in pitch and loudness, rather than discrepancies in articulatory or segmental timing.
Underwater target detection based on fourth-order cumulants beamforming
Authors: Li Xiukun , Jia Hongjian , Yang Mei
Published: November 2017

Obtaining the target echo data of high signal to reverberation ratio (SRR) or signal to noise ratio (SNR) in the complex ocean environment is a key problem to improve the detection capability of underwater targets. In this paper, combined with the expansion characteristics of fourth-order cumulants to the array aperture and the structure of the smallest redundant array, a robust and high-resolution fourth-order cumulants beamforming method based on the smallest redundant array is presented. The target direction-of-arrival estimation (DOA) is achieved by forming a narrow space beam, while the reverberation interference is reduced. For the broadband detection system, combined with fractional Fourier transform (FRFT), the fourth-order cumulants beamforming method is extended to the DOA estimation of LFM signal. According to the signal characteristics difference between the target echo and the reverberation, the reverberation is filtered out in the FRFT domain, which achieves the secondary suppression of reverberation interference in the spatial domain and the transform domain, and further improves the SRR of the target echo signal. The validity of the research method is verified by the processing results of the active sonar target detection experiment.
Discrete element method simulations for acoustic propagation through idealized seafloor sediments
Authors: Calantoni Joseph , Seyfarth Adam , Jordan Pedro M. , Keiffer Richard S.
Published: November 2017

We performed discrete element method (DEM) simulations for the propagation of pressure and shear waves in idealized seafloor waveguides. Preliminary simulations used identical spheres configured in a random loose pack. DEM waveguides were essentially one-dimension with a 10 by 10 grain diameter cross section and varied in length from 20,000 to 100,000 grain diameters for grains ranging from 0.2 to 0.5 mm in diameter with the material properties of quartz. Rough walls were placed at the ends of the waveguide and periodic boundaries were used in the lateral direction. Pressure and shear wave propagation was simulated through normal and tangential sinusoidal oscillation of the boundary wall at frequencies ranging from 100 to 1,000 Hz. Sensitivity of propagation speed and attenuation to the specification of the material properties of the grains was investigated. For example, our simulations demonstrate the well-known dependence of pressure wave propagation speed on grain stiffness. Discussion will focus on creating links between simulation results and continuum models for acoustic propagation in seafloor sediments.
Carbon nanotube coaxial thermophone for automotive exhaust noise cancellation
Authors: Prabhu Suraj M. , Barnard Andrew R. , Asgarisabet Mahsa
Published: November 2017

Exhaust noise from automobiles is a major concern and needs to be controlled. Current noise control systems, mainly mufflers, have significant size, weight, and performance limitations at low frequencies. Passive control systems are unable to cancel noise efficiently over the entire frequency spectrum. Active noise control system helps to overcome the above limitation. This paper deals with the design and testing of a coaxial carbon nanotube speaker for active cancellation of automotive exhaust noise. Carbon nanotubes are virtually massless and work on the thermo-acoustic principle. Their ability to sustain heat makes them suitable for use in elevated temperature environments such as automotive exhausts. Analytical calculations are performed using transfer matrix method to evaluate the effect of coaxial thermo-phone and side branch speakers on the sound pressure level in the exhaust tailpipe. Design of the coaxial CNT thermophone and testing of it by mounting on an automotive exhaust tailpipe are discussed. Low frequencies (20 Hz–1000 Hz) are considered to evaluate the performance of the thermophone. For active cancellation of exhaust noise, Filtered-X Least Mean Square (FXLMS) algorithm is developed and implemented using NI LabVIEW.
A spherical harmonics basis for quantifying the isotropy of sound fields in reverberant enclosures
Authors: Nolan Mélanie , Brunskog Jonas , Jeong Cheol Ho
Published: November 2017

This study examines an experimental method for evaluating isotropy in reverberant sound fields, based on an analysis in the spherical harmonics domain. The methodology relies on estimating the wavenumber (or angular) spectrum of the sound field in the room, to characterize the magnitude of the waves arriving from definite directions at the observation point. Subsequently, the obtained wavenumber spectrum is expanded into a series of spherical harmonics, and the multipole moments from the spherical expansion are used to characterize the isotropy of the sound field. This spherical harmonic basis is best suited for characterizing isotropy, as it provides an unequivocal characterization of the symmetry of the wave field. The work examines how theoretical considerations compare with experimental results obtained in various rooms with diverse diffuse field conditions. The experimental results are based on automated measurements using a scanning robot. In addition, the corresponding spatial distribution of the active soundintensity field is determined, making it possible to benchmark the proposed methodology with direct observations of the energy flows in the sound field.
Decadal assessment of the sperm whale population trends in the northern Gulf of Mexico using acoustics
Authors: Li Kun , Sidorovskaia Natalia , Tiemann Christopher , Ackleh Azmy S.
Published: November 2017

Passive acoustic monitoring data have been used to assess population trends of sperm whales in the northern Gulf of Mexico. In this paper, the variability of sperm whale abundance in the Mississippi Canyon area derived from acoustic data collected between 2001 and 2017 is discussed in relation to seasons, habitat type, ambient noise levels, and environmental disturbances. The results have shown that sperm whales were present in the region throughout the entire monitoring period with lower activity in winter months. A considerable habitat shift was observed after the 2010 oil spill with sperm whale activity higher at the sites further away from the spill site. The results clearly indicate the importance of long-term spatially distributed acoustic monitoring in characterizing changes in Gulf of Mexico marine mammal population and their habitat.
Species-level classification and clustering of beaked whale echolocation recordings
Authors: LeBien Jack G. , Ioup Juliette W.
Published: November 2017

The Littoral Acoustic Demonstration Center—Gulf Ecological Monitoring and Modeling (LADC-GEMM) consortium has collected passive acoustic monitoring data in the northern Gulf of Mexico since 2001. Recordings were made in 2007 near the Deepwater Horizon oil spill, which have provided a baseline for an extensive study of regional marine mammal populations in response to the disaster. Beaked whales are of particular interest as they remain one of the least understood groups of marine mammals, and relatively few abundance estimates exist. Efficient classification and clustering algorithms are demanded for mining the long-term passive acoustic data. Three algorithms using k-means, self-organizing maps, and spectral clustering are tested with various features of detected echolocation transients. Several methods are observed to effectively isolate recorded echolocation clicks of regional beaked whale species. The waveform fractal dimension is introduced as a feature for marine biosonar classification and shown to improve accuracy. A feedforward neural network classifier is also evaluated and shows performance with high accuracy under various noise conditions. [This research was made possible by a grant from The Gulf of Mexico Research Initiative. Data are publicly available through the Gulf of Mexico Research Initiative Information & Data Cooperative (GRIIDC) at https://data.gulfresearchinitiative.org.]
Quantitative analysis of the angiogenic microvasculature in tumor using multiple scattering and dual-frequency transducers
Authors: Joshi Aditya A. , Li Sibo , Kasoji Sunny , jiang xiaoning , Dayton Paul , Muller Marie M.
Published: November 2017

The objective is to characterize angiogenic networks using contrast-enhanced multiple scattering. The methods relies on the measurement of the diffusion constant from the time evolution of the incoherent backscattered intensity. Dual-frequency arrays allow to emit a pulse at a frequency close to resonance frequency of microbubbles, and to receive the backscattered echoes at higher harmonics, resulting in better contrast-to-tissue ratio compared to single frequency transducers. At 8 MHz, we demonstrated that the diffusion constant enables the quantification of the vascular density and anisotropy in tumor-related vasculature in rat models in vivo. We show here that the results could be further improved using a dual-frequency approach, using two linear arrays with different central frequencies (7 MHz/18 MHz) and using a custom made dual frequency transducer (3 MHz/15 MHz). The minimum detectable distance between two vessel-mimicking cellulose tubes filled with contrast agents was measured via the diffusion constant. The dual-frequency approach drastically reduced the smallest detectable distance between tubes, which was found to be 25µm using a single frequency, 20µm using two linear arrays and 10µm using the custom dual-frequency array, respectively. These results show that measuring the diffusion constant with a dual frequency array can enable the quantification of vessel density with high accuracy
Quantitative-ultrasound-based prostate-cancer imaging by means of a novel micro-ultrasound scanner
Authors: Rohrbach Daniel , Wodlinger Brian , Wen Jerrold , Mamou Jonathan , Feleppa Ernest
Published: November 2017

Currently, transrectal ultrasound (TRUS) guided biopsy is the only method for definitive diagnosis of prostate cancer. Our current study used a high-frequency (i.e., 29-MHz), transrectal, micro-ultrasound system (ExactVu™ micro-ultrasound, Exact Imaging) to acquire RF data from 163 patients immediately before needle firing during 12-core biopsy examinations. Quantitative ultrasound (QUS) estimates of effective scatter diameter (ESD), effective acoustic concentration (EAC), midband (M), intercept (I), and slope (S) were calculated. Additional QUS estimates were derived including envelope statistics employing a Nakagami distribution and the envelope signal-to-noise ratio (ESNR). Estimate values were used to train linear-discriminant classifiers and performance was assessed using area-under-the-curve (AUC) values obtained from receiver operating characteristic (ROC) analyses based on 10-fold cross validation. A combination of ESS- and EAC-related parameters produced an AUC value of 0.75. When ESNR or PSA value was added as a feature, the AUC increased significantly to 0.77 or 0.78, respectively. The best classifier performance was obtained by combining envelope statistics, PSA, ESD, and EAC, which produced an AUC of 0.80. Our initial results with AUC values of 0.80 are very encouraging for developing a new tool for prostate-cancer biopsy guidance and treatment.