bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement and modeling of scattering in underwater acoustics: A potential value to architectural acoustics?
Authors: Siderius Martin , Bradley David , Zurk Lisa
Published: October 2013

Scattering measurement and modeling techniques in underwater acoustics have undergone significant progress through several decades of research. The knowledge gained from this research can be applied to similar scattering problems found in above water systems, such as those typically seen in architectural acoustics. Underwater environments have inherently complex scattering behavior including multiple propagation paths and boundaries that are rough and spatially variable. Additionally, boundaries are often moving, which can introduce different Doppler shifts on multipath arrivals, referred to as Doppler spread. These complications make modeling underwater propagation and scattering a challenging problem. However, there are currently several models that are routinely used for predicting underwater acoustic behavior. In some cases, deterministic modeling can be used while in others the complexity only allows for a statistical description of the acoustic field. In recent years, acoustic communications have emerged as an important ocean application, and the innovations provided by these systems have pushed the limits of current techniques. An overview of these modeling and measurement techniques will be presented, and the lessons learned from recent advances will be reviewed in the context of identifying commonalities between underwater and architectural acoustics.
From mysticete song to odontocete echolocation: Monitoring cetacean sounds with high-frequency acoustic recording packages (HARPs).
Authors: Wiggins Sean M. , Hildebrand John A.
Published: October 2013

Marine mammals produce a wide range of sounds from 10s of Hz to 100s of kHz. To remotely monitor these various sounds with autonomous systems, instruments with wide bandwidths are required. A general purpose, autonomous, high-frequency acoustic recording package (HARP) is described that can record sounds ranging from low-frequency blue whale (Balaenoptera musculus) song to mid-frequency dolphin whistles and beaked whale sweeps to high-frequency dolphin clicks. In addition to monitoring marine mammals, sounds from fish, contributions from wind and rain, and anthropogenic sources such as ships and sonar also are recorded potentially allowing for the study of cetacean behavioral response to these sounds. HARPs have been deployed for periods of up to one year, in various configurations such as standard moorings, seafloor packages, and arrays, and in remote locations including the Arctic, Bering Sea, Gulf of California, around Hawaii, and offshore of Washington State and southern California. The various configurations of these deployments and the wide range of marine mammal monitoring data they have provided are discussed in addition to lessons learned from these studies. [Work supported by the U.S. Navy CNO-N45.]
Extending passive acoustic capabilities of autonomous recorders by using multiple hydrophones.
Authors: Thode Aaron , Glatts Robert , Burgess William C.
Published: October 2013

Low-power data acquisition systems have attained sampling rates large enough to enable multielement hydrophone arrays to be deployed autonomously, at the cost of reducing the individual sampling rate per phone. This paper discusses what theoretical advantages bandlimited multielement recordings can provide over single-hydrophone data, including array gain for increased detection range, interfering noise source rejection, environmental inversion, and biological source tracking. These points are illustrated with data collected from an autonomous four-element vertical array off Queensland, Australia in 2003, and data collected from an autonomous eight-element, 21 m aperture vertical array deployed at 35 m depth in the Beaufort Sea in 2008. These examples also provide insight into the technical and logistical challenges required by such deployments, including deployment and recovery systems that do not endanger or entangle array cables. [Work supported by NPRB, logistics provided by Greeneridge Sciences and Shell Co.]
Environmental acoustic recording system (EARS) buoys for marine animal acoustics.
Authors: Ioup George E. , Ioup Juliette W. , Tashmukhambetov Arslan M. , Pflug Lisa A. , Newcomb Joal J. , Sidorovskaia Natalia A. , Kuczaj Stan A. , Rayborn Grayson H. , Stephens James M. , Tiemann Christopher O. , Bernstein Alan
Published: October 2013

EARS buoys were developed as autonomous, moored, underwater recording systems by the Naval Oceanographic Office (NAVOCEANO) to make long-term ocean ambient noise measurements. When the Littoral Acoustic Demonstration Center (LADC) was formed as a consortium of university and U.S. Navy scientists in 2001, the buoys were capable of measuring up to 1000 Hz for 1 yr. LADC added listening to sperm whales to its noise and propagation measurements. NAVOCEANO quickly modified the buoys to measure up to 5859 Hz for 36 days. The buoys, moored at depths from 550 to 950 m in the Gulf of Mexico, produced exceptionally clear recordings of sperm whale echolocation and coda clicks and recordings of other whales. EARS Generation 2 buoys are now capable of recording one channel to 96 kHz, or four channels to 25 kHz, for more than 13 days on four 120 Gbyte notebook disk drives. Experiments in the Gulf of Mexico and the Ligurian Sea have targeted both sperm and beaked whales. Audio results and visualizations of these recordings reveal rich detail of Odontocete clicks and enable new analyses, such as the identification of individual whales from the properties of their clicks. [Research supported by ONR and SPAWAR.]
The estimation of geoacoustic parameters via low frequencies (50–75 Hertz) for simulated shallow water test scenarios.
Authors: Tolstoy A.
Published: October 2013

This work will demonstrate the success of using only a variety of low frequencies (50–75 Hz) for geoacoustic inversion in simulated SW06 environments. The environments include a variety of scenarios (a thin, medium, or thick sediment layer over a half-space), broadband sources at approximately 1 km range (rge), and a vertical array consisting of 16 phones whose depths are approximately known, i.e., we assume that array element localization was available so that we can estimate phone depths (zphi) to within about 1 m. The source depths (zsou) and water depths (D) are approximately determined via time domain crossings seen at the array [see A. Tolstoy, J. Acoust. Soc. Am. 123, 3106 (2008)]. Additionally, the ocean sound-speed c(z) is assumed to be range-independent and approximately known, e.g., via measurements or archival data. The use of only the 50–75 Hz portion of the signal results in a need for less than perfect accuracy for zphi and c(z) while still giving excellent accuracy for estimated bottom parameters. Geometric parameters (such as rge, zsou, D, zphi) and c(z) would be more accurately determined by means of higher frequencies but this would require much more CPU time. Uniqueness of the final “solution” is achieved for all but the thin sediment scenario.
Shock wave lithotripsy treatment at 60 shock waves per minute is an appropriate protocol to minimize tissue injury.
Authors: Connors Bret , Evan Andrew , Blomgren Philip , Handa Rajash , Johnson Cynthia , McAteer James , Willis Lynn , Lingeman James
Published: October 2013

Previous work has shown that the size of the renal hemorrhagic lesion caused by extracorporeal shock wave lithotripsy (SWL) is greatly reduced when shock waves (SWs) are delivered at 30 SWs/min instead of at the more commonly used rate of 120 SWs/min (0.08±0.02% versus 3.93±1.29% of functional renal volume, P=0.006). However, slowing the SW rate to 30 SWs/min greatly increases treatment time. Consequently, we investigated whether an intermediate rate of 60 SWs/min also reduces lesion size compared to treatment at 120 SWs/min. Methods: one kidney in 12 juvenile pigs was treated at 120 SWs/min (n=7) or at 60 SWs/min (n=5) with an unmodified Dornier HM-3 lithotripter (2000 SWs, 24 kV). After lithotripsy, the treated kidneys were fixed and removed to determine lesion size. Results: SWL at 60 SWs/min significantly reduced the size of the morphological lesion compared to 120 SWs/min (0.42±0.23% versus 3.93±1.29%, P=0.034). This reduction in lesion size was comparable to the lesion produced at 30 SWs/min. Conclusions: SWL applied at 60 SWs/min produces significantly less renal injury than SWL at 120 SWs/min, and produces an equivalent level of injury as that seen at 30 SWs/min.
Renal heme oxygenase-1 upregulation after shock wave lithotripsy.
Authors: Clark Daniel L. , Connors Bret A. , Evan Andy P. , Handa Rajash K. , Johnson Cynthia D.
Published: October 2013

Shock wave lithotripsy (SWL) is known to induce oxidative stress and a rapid inflammatory response in renal tissue. The purpose of this study was to determine the location and quantify markers for oxidative stress and inflammation in a porcine model of acute SWL-induced renal injury. The lower pole calyx of left kidneys of female pigs received 2000 shock waves at 24 kV/2 Hz from a Dornier HM3 lithotripter and subsequently monitored for 4 h. Heme oxygenase-1 protein (HO-1) was measured in renal microsomes by Western blot. Renal medulla HO-1/β-actin ratios were 1.186 ± 0.48 for treated pole (F2), 0.293 ± 0.23 for treated kidney upper pole, and 0.122 ± 0.075 for contralateral kidney (n=6). Thus, we observed an eightfold induction of HO-1 in renal medulla at F2 compared to the upper pole medulla of the treated kidney and the contralateral kidney medulla. In contrast, renal cortex at F2 did not show a similar HO-1 induction. The highly localized HO-1 induction in SWL-treated renal medulla parallels our previously reported finding of interleukin-6. These data together suggest that an early inflammatory response and oxidative stress appear primarily in the treated renal medulla within 4 h after SWL. [Work supported by NIH].
Low-energy shock wave pretreatment results in greater vasoconstriction and less injury in the kidney compared to high-energy shock wave lithotripsy treatment alone.
Authors: Handa Rajash K. , Evan Andrew P. , Connors Bret A. , Willis Lynn R. , Gao Sujuan , Paun Marla , Bailey Michael R.
Published: October 2013

Pretreating the kidney with low-energy shock waves (SWs) before administering a clinical dose of high-energy SWs has been found to greatly decrease the hemorrhagic lesion that normally results from high-energy shock wave lithotripsy (SWL) treatment alone. We tested the hypothesis that this novel pretreatment SWL protocol results in a greater and/or earlier renal vasoconstriction than clinical SWL alone, which could potentially explain the reduced bleeding in the kidney. Anesthetized pigs were treated with a clinical dose of SWs (2000 SWs, 24 kV, 120 SWs/min) or the pretreatment protocol (500 SWs, 12 kV, 120 SWs/min + 3-min pause + 2000 SWs, 24 kV, 120 SWs/min) using the HM3 lithotripter. Sonography (color and pulsed ultrasound) was used to locate a resistance artery within the SW-treated pole of the kidney and to take resistance index (RI) measurements from the blood vessel to estimate the resistance/impedance to blood flow. The results demonstrated that RI increased (renal vasoconstriction) earlier and greater during the pretreatment protocol compared to normal clinical SWL. Constricted blood vessels would likely be less prone to rupture by SWs and, if broken, would bleed less—resulting in a smaller hemorrhagic lesion.
Efficiency of spark discharge in electrohydraulic lithotripsy.
Authors: Pishchalnikov Yuri A. , Kaehr Mark M. , VonDerHaar R. Jason , Pishchalnikova Irina V. , McAteer James A.
Published: October 2013

Electrohydraulic lithotripters and SWT devices generate shock waves by discharge of a high-voltage capacitor through submerged electrodes. As the electrodes age, the interelectrode gap widens. How this affects the efficiency of spark generation was studied using a research HM3-clone lithotripter. Widening of the interelectrode gap (∼0.3 mm with new electrodes; ∼2.5 mm after 4000 discharges) increased the lag-time to breakdown (∼0 to ∼30 μs, respectively). Increased lag-time as electrodes aged was associated with partial discharge of the capacitor (leakage promoted by ∼0.6 mS conductivity of the surrounding water), such that the average energy remaining at the capacitor at the moment of breakdown was reduced four times compared to new electrodes. However, with new electrodes almost 90% of the energy was lost in the circuitry rather than in the spark, as the resistance of the spark (R∼0.03 Ω) was much smaller than the resistance of the remainder of the circuit—including the high-voltage switch and connective wires (r∼0.23 Ω). With old electrodes, most of the energy was released in the spark, as the electric efficiency R/(R+r) approached ∼90%. The product of electric efficiency and capacitor energy agreed closely with both the acoustic energy and the volume of the primary bubble produced at spark discharge. [Work supported by NIH-DK43881.]
In vivo simulation of shock wave lithotripsy: Wave focusing in inhomogeneous materials.
Authors: Krimmel Jeffrey , Colonius Tim
Published: October 2013

Shock wave generation and focusing in electrohydraulic, electromagnetic, and piezoelectric lithotripters are simulated numerically. Inhomogeneities associated with wave propagation in vivo are modeled using data from The Visible Human Project. The approximate time-domain relaxation model of Yang and Cleveland (2005) was used to simulate attenuation and dispersion in the tissuelike media. The simulations utilize a MUSCL-type shock capturing scheme with adaptive mesh refinement (AMR). In vitro focal region pressure measurements compare favorably with available experimental data for each lithotripter type. Preliminary in vivo simulation results show significant dispersion associated with the nonuniform sound speed, including increases of up to 50% in focal pressure amplitudes and the presence of multiple pressure minima/maxima in the focal waveform. We will also discuss the extension of the AMR framework to account for cavitation via a previously developed ensemble-averaged continuous two-phase flow model.
Lung hemorrhage produced by exposure to underwater acoustic impulses.
Authors: Dalecki Diane , Child Sally Z. , Raeman Carol H.
Published: October 2013

Underwater acoustic impulse sources are used in various commercial and military applications. The objective of this study was to investigate the response of mammalian lung to exposure to underwater acoustic impulses. A laboratory-based acoustic exposure system was developed to investigate the bioeffects of underwater impulses. Underwater acoustic impulses were generated using a ten cubic inch air gun operated in a large water tank. Underwater acoustic impulses with peak pressure amplitudes ranging from 0 (sham) to 110 kPa were investigated. Experiments were performed with anesthetized adult mice. Each exposure consisted of five acoustic impulses with approximately 20 s between impulses. Mammalian lung hemorrhage can occur in response to exposure to underwater acoustic impulses. The pressure threshold for lung hemorrhage resulting from five air gun impulses was approximately 50 kPa. The extent of lung damage increased with increasing pressure amplitude. The results of this work are relevant to establishing safety guidelines for swimmers and divers exposed to underwater sound fields.
Prediction methodologies for tonal and broadband noise from horizontal-axis wind turbines.
Authors: Paul Brent , Martinez Rudolph , Thompson Donald , Uhlman James
Published: October 2013

This paper describes a set of computational-analytic predictive tools for the following mechanisms of aerodynamic sound and vibration for a wind turbine’s blades in ducted or open arrangements: (a) Infrasound and tonal low-frequency nearfield noise from the interaction of blades with a nonuniform meanflow that is steady in its own reference frame; (b) mid-frequency broadband noise from the “haystacked” chopping of an incident turbulent freestream; (c) high-frequency noise from self-generated turbulence near the trailing edge of each blade’s suction side. Contributors to tonal mechanism (a) include the rotor’s static loads as required by power generation (nearfield “Gutin” component of infrasound), and operation in a local wind shear or in the mean wake of the turbine’s tower when set up as a downstream machine. These predictive tools include models of the spatially nonuniform mean and turbulent flows that typically strike a wind turbine’s blades, as well as preprocessors of that information when made available by either field measurements or off-line calculations. The codes’ physical content includes the possibility of uneven spacing for the turbine’s blades and for their interaction with statistically inhomogeneous turbulence for mechanism (b). Sample predictions compare the codes’ estimates of sound production to measurements from the open literature.
Vibration analysis of turbine low-pressure bladed-disk in 500-MW fossil power plant.
Authors: Lee Dooyoung , Bae Youngchae , Kim Heesoo , Lee Yookryun , Choi Hongil , Lee Hyun
Published: October 2013

Many failures of turbine blades are caused by the coupling of aerodynamic forcing with bladed-disk vibration characteristics. Vibration analysis for an individual turbine blade does not include all the coupled characteristics of whole bladed-disk system. This paper shows the coupled vibration characteristics of a low-pressure (LP) turbine bladed-disk in a 500-MW fossil power plant for the purpose of confirming equipment integrity. In order to verify the finite element model, analytic and experimental modal analyses for a single blade were performed and reviewed with boundary conditions not only where both ends were free to move but also where its root was fixed. Natural frequencies and corresponding mode shapes were calculated for the bladed-disk first, and then proximity of modes to sources of excitation was assessed by means of interference diagrams to examine resonance. The result of analysis was ascertained by being compared with a field test for the bladed-disk without centrifugal and aerodynamic forces. In addition, dynamic stress as well as steady stress which results from centrifugal and steady-state steam forces was also calculated at dangerous modes of operation. It is expected that these dynamic characteristics will be used effectively to identify the root causes of blade failures and to perform prompt maintenance.
Sound speed measurements in air using a variable sound source and tubes.
Authors: Cheyne Stanley A. , McDermott Walter C.
Published: October 2013

Sound speed measurement using standing waves and tubes is a standard experiment in every introductory physics laboratory. It is an experiment that is relatively simple to understand both conceptually and mathematically. The idea behind this work is to reproduce the same experiment, at low cost, making it suitable for project listen up. Two approaches were made. The first was to design and construct a small, low cost, variable sound source that could be used to determine the resonances of several fixed length tubes. The device is simple in design and easy to use. As the frequency is varied, the resonances can be determined by listening with the ear. Once done, the sound speed can be easily calculated. The second method was to use a free, online, function generator as the sound source and repeat the experiment as previously discussed. Results of both methods will be given and demonstrated along with pros and cons of each.
Acoustics outreach and scouting: A merit badge proposal.
Authors: Gee Kent L. , Anderson Brian E. , Neilsen Tracianne B. , Sommerfeldt Scott D.
Published: October 2013

The success of the Girl Scouts of America (GSA) and the Optical Society of America’s “Project Lighten Up” and the proposed “Project Listen Up” have prompted a discussion of how Scouting can be used as an outreach vehicle to interest today’s youth in science and, more particularly, in acoustics. One possibility for this would be the drafting of a “Sound and Audio” merit badge for the Boy Scouts of America (BSA) or a similar activity award for the GSA. The BSA currently offers 121 merit badges for scouts, including varied topics such as archeology, rifle shooting, plumbing, truck transportation, and coin collecting. Although there are physical science-related merit badges (e.g., composite materials, chemistry, nuclear science), there is not a badge that deals directly with acoustics. This talk will outline how an acoustics-related merit badge may help engage youth interest in science and discuss ideas for possible badge requirements.
Wave interaction effects for all ages.
Authors: Sommerfeldt Scott D.
Published: October 2013

Wave interaction effects occur in many everyday situations. A number of important principles associated with these interactions can be readily demonstrated without the need for extensive and expensive equipment. Using two low-cost speakers, it is possible to easily demonstrate the basic principle underlying active noise control by placing the speakers close together and first wiring the speakers “in-phase” to achieve constructive wave interference and then wiring the speakers “out-of-phase” to achieve destructive wave interference. This setup results in a global attenuation of the sound field, making the audible effect easily discernible. The dependence of the interaction on frequency and spacing (kd) can be demonstrated by changing the frequency of the excitation signal. In addition, by separating the speakers the interaction of two waves to create a standing wave can be demonstrated, and the nodes/antinodes established can be audibly heard as the listener moves his/her ear through the field. Finally, these concepts can be used to understand why loudspeakers are mounted in enclosures. As the loudspeaker is placed in an enclosure the direct interaction of (out-of-phase) waves from the front and back of the loudspeaker cone is inhibited, thus resulting in increased radiation efficiency.
The effect of the teaching-learning sequences connecting sound wave at microlevel and macrolevel on the student’s understandings for sound transmission.
Authors: Kim Hyungjun , Yoo Junehee
Published: October 2013

Previous studies reported that students had some difficulties in understanding sound waves as longitudinal waves. In this research, most of teaching-learning sequences described sound waves at macrolevel, which were supposed as one source of these difficulties. So teaching-learning sequences connecting sound wave at microlevel and macrolevel were developed and effects were investigated. These teaching-learning sequences were focused on bridging between the movement of particles in air and movements of slinky springs and simulation using the EXCEL program. In addition to that, explaining wave phenomena at macrolevel by the movement of particles at microlevel was emphasized. Predict-observe-explain strategy was used. Evaluated worksheets and video-records were analyzed to figure out conceptual changes.
Qualification of an aircraft ground run-up enclosure using a novel sound monitoring and analysis approach.
Authors: Standlee Kerrie G.
Published: October 2013

This paper describes a sound monitoring and analysis program developed to determine if a ground run-up enclosure (GRE) installed at the Portland International Airport was effective in reducing aircraft engine run-up noise radiated to residential neighborhoods during nighttime hours. A noise monitoring and analysis program was developed to fulfill conditions of approval imposed by the Oregon Department of Environmental Quality (DEQ) prior to the construction of the facility. A novel approach was developed whereby unattended sound level meters were used to collect one-second Leq and hourly statistical noise level data near the GRE and at community locations of interest. This data, combined with GRE usage data and weather data, was then subjected to a multistep analysis procedure. The process was found to be very effective at determining when ground run-up events caused community noise levels exceeding DEQ limits. By the end of the project, the procedure was being used to assess 99 percent of the run-ups occurring within the GRE. The sound monitoring and analysis procedure became a very reliable tool in demonstrating that the GRE complied with its conditions of approval.
Noise issues affecting litigation in condominiums.
Authors: Lilly Jerry G.
Published: October 2013

Serving as an expert witness in legal actions involving residential condominiums is often a harrowing and extremely challenging task, regardless of which side you represent. If you are representing the HOA, you have to educate your client so that they understand that the mere ability to hear your neighbor is not necessarily unusual and may not be grounds for a defect. If you are representing the architect, developer, or contractor, you have to educate them as to the code requirements as well as the various acoustical performance guidelines that will undoubtedly be introduced by the HOA. In either event, if you do not do your homework you are leaving yourself exposed to be grilled by opposing counsel (in deposition or at trial) without mercy. This presentation will discuss the author’s experience in dealing with these issues, with specific emphasis on problems with the testing standards and performance guidelines that exacerbate the problem.
Deficiency of the Massachusetts Pure Tone Noise Regulation.
Authors: Bahtiarian Michael
Published: October 2013

The Commonwealth of Massachusetts Department of Environmental Protection (MADEP) noise regulation has two parts. The first part involves overall A-weighted noise and requires that no source of sound be greater than 10 dB above the background noise. A second part states that no pure tones are allowed. A pure tone condition is defined by the MADEP as any octave band that is greater than the adjacent bands by 3 dB. The author was involved in community noise investigation that showed the deficiency of the pure tone requirement. A suburban community complained of bothersome noise from an industrial abutter. Noise measurements were taken by other consultants which did not register as a pure tone. The author was hired by the community group to conduct measurements on their behalf. Similar octave band measurements were taken with similar results. However, measurements with finer one-third octave band showed significant tonal activity. When compared to commercial standards for pure tones the tonal criterion was met. Further examination of narrowband data showed why the original octave band measurements were not registering pure tone conditions. The author will present his suggestion for changes to the MADEP regulation and welcomes input from others dealing with similar tonal requirements.
Uncertainty in field and laboratory acoustical testing: A challenge for the acoustical industry.
Authors: LoVerde John , Dong Wayland
Published: October 2013

The statistical uncertainty in acoustical testing has been insufficiently studied in the acoustical community. There are a limited number of studies quantifying measurement uncertainties, especially in the field, but even where uncertainties have been documented, they are largely ignored in practice. As was documented in a previous case [LoVerde and Dong, J. Acoust. Soc. Am. 124, 2441 (2008)], it is common practice to assume that the test results have low uncertainties (even if published uncertainties are large) and that variations in the results are due to variations in materials, errors in construction, etc. This can be particularly important in noise litigation, where acoustical ratings that are lower than expected are often automatically assumed to be due to construction defect, even though they may be within the expected range. Even without errors in construction, the uncertainties in the acoustical test procedure may be such that some assemblies will meet the relevant statutory requirements and other, nominally identical assemblies will fail. Recent experience and insight will be presented regarding the definition of a construction defect in acoustical assemblies, the overlap of responsibilities between contractors and designers, and the interpretation of building code requirements.
On tropospheric ducting in infrasound.
Authors: Waxler Roger , Blom Philip
Published: October 2013

Infrasound can propagate to ranges of many hundreds of km. Signals received on the ground at ranges of 200 km or more have propagated high into the atmosphere through the stratosphere and thermosphere. At shorter ranges, the propagation is dominated by structure in the lower atmosphere such as the jet stream and the atmospheric boundary layer. Theoretical results on the influence of the lower atmosphere on infrasound propagation will be presented.
Study of the impact of input uncertainties on acoustic propagation.
Authors: Ikelheimer Bruce , Downing Micah , James Michael
Published: October 2013

A modular system of acoustical tools has been developed that integrates the physical factors controlling the propagation of acoustical signals. First and foremost, this system provides a prediction of the noise from a source to a receiver location. This ray-tracing prediction takes into account the local terrain, changes in ground impedance, turbulence, and thermal and wind gradients. This propagation prediction is combined with a noise source that can handle fully three-dimensional, spectral source descriptions. The model uses a six-dimensional definition of the source location and orientation to select the radiation angle from the source to the receiver. Levels of audibility of the received signal are then calculated based on the received noise levels, the local ambient noise levels, and the expected listener acuity. Each input to the model has uncertainties with the potential to generate errors that cascade through the system. Differing atmospheric, terrain, and ground impedance conditions have been tested in our model both individually and in combinations to see how they interact. The goal is to have an understanding of the confidence level of audibility provided a known level of uncertainty on the input data.
Rise times of low-energy, free-space propagating acoustic shocks.
Authors: Gabrielson Thomas B. , Marston Timothy M. , Wochner Mark S.
Published: October 2013

Characteristics of the “ideal” shock, a one-dimensional step change in pressure, are reasonably well established; however, the freely propagating shock with finite duration is challenging to model and measure. These challenges are reflected in an extensive body of literature over several decades. In this paper we present a method for producing free-space propagating shocks, measurements of rise time with minimal contamination by turbulence, and model results that account for spreading, absorption (including molecular relaxation), and nonlinearity. The shocks are produced using an acoustic pipe filter to condition the irregular pressure release of either balloon pops or starter-pistol shots. The shocks range in peak pressure from 10 to 1000 Pa and in rise time from 10 to 0.5 μs. Rise-time measurements are made using a custom piezoelectric polymer wideband microphone with a measurement range that overlaps with that of a diffraction-corrected 1/8-inch measurement microphone. The exponential-decay time constant beyond the pressure peak is typically less than 100 μs, which may be too rapid to permit development of characteristics associated with relaxation mechanisms: rise times over the entire range measured here are well predicted by accounting for classical and rotational absorption only.
A personal perspective on unilateral hearing loss.
Authors: Dushaw Brian D.
Published: October 2013

Although I have been unilaterally deaf since birth, only later in life have I realized the extent of this handicap and how I can best manage it. The effects of this hearing loss are complicated, being an interplay of physics, psychology, social interaction, etc. Because people are able to adapt, the extent of this “unseen” handicap is underappreciated. Responses by the public to an informative website (http://909ers.apl.washington.edu/∼dushaw/SSD) suggest that this handicap has a universal nature. Obvious effects are the inabilities to locate sound or to bilaterally process sound signals. Less obvious effects are a heightened sensitivity to noise: as masking to a desired signal, as a fatigue factor, as an impediment to mental concentration. The difficulties encountered when talking over the telephone to someone who is speaking in a noisy environment may give one an appreciation of the effects. Even less obvious effects are the long-term social implications of the handicap: the tendency to ignore those on one’s deaf side, the inability to function “normally” at noisy events such as parties, ASA receptions, etc., or a tendency to irritability in noisy environments. In this unscientific talk, I will attempt to highlight issues that may be deserving of additional study.
Discrimination of formant-like glides in gated noise: Effect of sensation level.
Authors: Nelson Peggy , Nie Yingjiu , Wojtczak Magdalena , Stecklein Gordon
Published: October 2013

Listeners with sensorineural hearing loss (SNHL) do not experience masking release for speech in fluctuating noise, as normal-hearing listeners do. One hypothesis suggests dip listening may be difficult because frequency glides, or speech formant transitions, may be difficult to discriminate at low sensation levels when in the presence of fluctuating noise. Normal-hearing listeners were tested for their ability to discriminate 100-ms frequency glides with center frequencies of 800 and 2500 Hz. They were tested in quiet and in the presence of 500-ms of 8-Hz square-wave gated broadband noise at a signal-to-noise ratio of −10 dB. Listeners were tested at low (10–15 dB SL) and moderate (30–40 dB SL) signal levels. Preliminary results suggest that glide discrimination thresholds (measured as % change) are similar for low- and moderate-level stimuli in quiet; glide thresholds are poorer in gated noise than in quiet; and glide thresholds are poorest when low-level stimuli were presented in gated noise. These results suggest that when formants or glides are presented at low levels and in gated noise, discrimination abilities may be reduced. Implications for understanding masking release for speech by listeners with hearing loss will be discussed. [Work supported by NIH 5R01DC008306.]
Masking release for speech in listeners with real and simulated hearing impairment.
Authors: Desloge Joseph G. , Reed Charlotte M. , Braida Louis D. , Perez Zachary D. , Delhorne Lorraine A.
Published: October 2013

The current study examined the effects of audibility and age on the release of masking for speech in interrupted versus steady-state noise in listeners with real and simulated hearing loss. The absolute thresholds of each of ten hearing-impaired listeners were simulated in normal-hearing listeners through a combination of spectrally shaped masking noise and multiband expansion for the octave bands with center frequencies from 0.25–8 kHz. Each individual hearing loss was simulated in two groups of three normal-hearing listeners (one age-matched group and one non-age-matched group). The speech-to-noise ratio (S/B) for 50%-correct identification of HINT sentences was measured in backgrounds of steady-state noise and temporally modulated (10-Hz square-wave) noise at two overall levels for unprocessed speech and for speech that was amplified with the NAL-PR prescription. Results indicate that the magnitude of the release from masking (the difference in S/B obtained in steady-state versus interrupted noise) observed in individual hearing-impaired listeners was generally well produced in both groups of simulated-loss listeners. Thus, release of masking appears to be determined primarily by audibility regardless of age. Predictions of masking release derived from the Speech Intelligibility Index (SII; ANSI S3.5-1997) will be compared to the observed values. [Work supported by NIH-NIDCD R01 DC00117.]
The perceptual tone-noise ratio of iterated rippled noise in listeners with hearing loss.
Authors: Leek Marjorie R. , Melamed Sarah , Molis Michelle R. , Gallun Frederick J.
Published: October 2013

Previous work has demonstrated that iterated rippled noise (IRN) produces a weaker pitch in hearing-impaired (HI) listeners than in normal-hearing (NH) subjects (e.g., Leek and Summers, 2001). In this study, the hypothesis was tested that the weaker pitch is a result of an increased perceptual noisiness of IRN for HI subjects. The tone-noise ratio (T/N) was developed by Patterson et al. (1996) to describe the relationship between the strength of the tone component and the strength of the noise component for a given IRN. The T/N was measured using an adaptive procedure to find the tone-plus-noise level that matched each IRN stimulus. Four NH and 4 HI subjects took part in the study. The stimuli were IRNs with delays ranging from 4 to 16 ms and with one to eight iterations. There was a significant effect of delay and of iteration number, with longer delays and more iterations producing greater T/N. There were no significant differences between subject groups. These findings suggest that the weaker complex pitch observed in listeners with hearing loss is not due to an abnormally noisy IRN percept but must be attributed to other impaired processing mechanisms. [Work supported by NIH.]
Near-field acoustic holography in conical coordinates.
Authors: Neilsen Tracianne B. , Gee Kent , Gardner Michael
Published: October 2013

Near-field acoustical holography (NAH) techniques can be optimized if the method capitalizes on the geometry of the noise source under investigation. Helmholtz-equation least squares method (HELS) uses the solutions of Helmholtz equation in spherical coordinates as basis functions for the pressure field. HELS is an efficient NAH technique if the source and the measurement surfaces are spherical in nature. For nonspherical cases, such as radiation from a plate or bar, it takes a large number of functions to represent the field. In these cases, there is also a question about where to place the origin of the wave functions. In search of a HELS-type method that could be applied to nonspherical sources, a study into the features of conical coordinates has been conducted. Because the Helmholtz equation is separable in conical coordinates, the solutions can be used, in a manner similar to HELS, as basis functions to represent the pressure field. For conical coordinates, the basis functions are spherical Hankel functions and Lame functions. This HELS-type formulation in conical coordinates could be a natural choice for NAH on conical sources and may be appropriate for NAH on jet noise. [Work supported by Blue Ridge Research and Consulting and Air Force Research Laboratory.]
Parameter study for Structural Health Monitoring based on ambient noise cross-correlation.
Authors: Leyla Najib Abou , Moulin Emmanuel , Assaad Jamal , Grondel Sebastien , Delebarre Christophe
Published: October 2013

The possibility of performing Structural Health Monitoring in aeronautic structures using ambient noise cross-correlation techniques has been investigated in previous works. The applicability of such methods has been validated by checking the reproducibility and the potential in terms of damage detection. In this paper, a more detailed description of the acoustic phenomena involved is given. The influence of the different parameters (source characteristics, sensors and damage positions, etc.) on the cross-correlation function has been studied. A theoretic study is presented and used to develop a simple simulation tool based on multipath reflections of ballistic waves. The simulated results have been successfully compared to finite element results in simple cases. This tool is then exploited to characterize and quantify the influence of the significant parameters. Finally, some optimization solutions of the technique are proposed, and experimentally validated.
Detection of structural faults in pipelines with time reversal.
Authors: O’Donoughue Nicholas A. , Moura José M. F. , Jin Yuanwei
Published: October 2013

The volatile nature of natural gas makes it extremely important to ensure that transport and distribution pipelines remain free from defects, as leakage can result in explosions. Current methods for testing buried pipelines rely on periodic excavation of a section of pipe and attachment of large acoustic or magnetorestrictive sensors. These systems, while reliable, suffer from a high cost-per-test ratio. To reduce the power requirements, we consider ultrasound embedded devices that could monitor the pipelines continuously. The problem with ultrasound is that, with buried pipes, the propagation is highly dispersive. We propose to use time reversal (TR), a signal processing technique, to refocus the signals and use, to our advantage, the dispersive nature of the environment. This paper will focus on the modes generated by various acoustic probing signals and the echoes received with and without TR. We argue that TR will be most beneficial when there are several dispersive modes present, a scenario avoided in conventional techniques. We will present simulation results for the detection of faults in a pipeline using PZFlex.
Selective excitation of microcantilever array using ultrasound radiation force.
Authors: Huber Thomas M. , Mellema Daniel C. , Abell Brad
Published: October 2013

The symmetric and antisymmetric eigenstates of a coupled pair of 500 956 m length microcantilevers were excited using the ultrasound radiation force. The excitation was produced using the difference frequency between the two sidebands of a double sideband suppressed carrier AM (DSB-SC-AM) waveform centered on 500 kHz that was emitted by a pair of focused ultrasound transducers. A laser Doppler vibrometer measured the frequency response and deflection shapes of the cantilever pair. When the waveforms sent to the transducer resulted in radiation force from both transducers with the same phase, it excited the 10.00 kHz symmetric state of the cantilever array while suppressing the 10.17 kHz antisymmetric state. Similarly, when the radiation force from the two transducers was 180 degrees out of phase, it selectively excited the antisymmetric state while suppressing the symmetric state. This ability to selectively excite different vibrational eigenstates is a unique capability of this noncontact for modal excitation.
Wave vector method for estimating acoustic vector quantities.
Authors: Thomas Derek C. , Gee Kent L.
Published: October 2013

Acoustic vector quantities such as particle velocity and intensity are usually estimated using the finite-difference technique. We present an alternate method, termed the wave vector method, for estimating vector quantities in acoustic fields in which the reactive intensity is small relative to the active intensity. This method utilizes the same equipment necessary for the finite-difference method, yet reduces sensitivity to sensor phase mismatch at low frequencies and eliminates bias error at high frequencies. The method is developed for arbitrary sensor configurations, and numerical results are presented for the special case of a regular tetrahedral configuration. [Work supported by NASA Stennis Space Center and STI Technologies.]
Source-filter interactions in birds—Theory and experimental evidence.
Authors: Mindlin Gabriel , Arneodo Ezequiel , Goller Franz
Published: October 2013

The diverse acoustic behavior of birds presents a rich source of natural vocalizations, some of which most likely reflect source-filter interaction. However, very little experimental evidence exists for the specific role of such interactions in shaping acoustic behavior or the functional relevance of the resulting acoustic features. As an example of how theoretical approaches can help explain acoustic observations, we discuss coexisting limit cycles in relaxation oscillators subjected to delayed feedback. The dynamical solutions of a nonlinear relaxation oscillator subjected to a delayed feedback are analyzed, and the equations under study are designed to model some aspects of the source-tract interaction in birdsong production. By deriving a phase equation for the system and analyzing its solutions, we are able to unveil analytical relationships between the parameters that lead to a variety of solutions. In particular, we study the coexistence of periodic solutions for similar pitch and first formant frequencies. These dynamical situations allow us to interpret the frequency jumps present in some birdsong syllables as an effect of the interaction between the source and the tract.
A possible role of nonlinear source-filter interaction in simulation of childlike speech.
Authors: Story Brad H.
Published: October 2013

Simulation (or synthesis) of natural-sounding childlike speech has long been a challenge. This is likely due, at least in part, to an incomplete understanding of the nonlinear interaction of the voice source and the vocal tract filter. Speech production by children is typically characterized by a fairly high fundamental frequency of phonation and a short vocal tract length that produces high formant frequencies. Together, these two characteristics suggest that low-numbered harmonics (including the fundamental frequency) may often, or even necessarily, be in close proximity to one or more of the formant frequencies. Such conditions may lead to a strong interaction of the acoustic pressures in the vocal tract and the glottal airflow, and possibly the vibration of the vocal folds. The purpose of this study was to use kinematic models of the vocal folds and vocal tract shape, scaled to approximately represent a 5-year-old child, to generate individual vowels and sentences. Waveshape and harmonic content of glottal area, glottal flow, and radiated acoustic pressure signals were compared across three vowels and one sentence. [Research supported by NIH R01-DC04789.]
Automatic classification of consonant-vowel transitions based on subglottal resonances and second formant frequencies.
Authors: Chen Nancy F. , Lulich Steven M.
Published: October 2013

A growing body of work indicates that subglottal resonances (SGRs) divide the frequency space of vowels and consonants into distinct regions in several languages [S. Lulich, J. Phonetics (in press), and references therein]. For instance, the second formant frequency (F2) of back vowels lies between the first and second subglottal resonances (Sg1 and Sg2), while for front vowels F2 lies at higher frequencies than Sg2. In alveolar stop bursts, F2 lies between Sg2 and the third subglottal resonance (Sg3). In this study, we build on previous work [S. Lulich, JASA 124, 2558 (2008)] to automatically determine SGRs using locus equations computed from 405 consonant-vowel (CV) transitions produced by an adult male native speaker of American English. Consonants and vowels are then classified into place of articulation and front/back features based only on the relations between F2 and the SGRs. The mean hit rate across categories was 77%, while the mean false alarm rate was 12%. These results show relative improvements of miss and false alarm rates by 21% and 14% from a baseline experiment, where F2 without SGRs was used to perform the classification. Our knowledge-based approach of classifying CV transitions is potentially useful when vowel and consonant identities are unavailable.