bluuebunny/crossref_metadata_2025 huggingface dataset:
An effective theory for meta-mass and meta-material mechanical/electrical devices
Authors: McCoy John J.
Published: November 2013

A dynamical system comprised of a rigid housing element that encapsulates a large multiplicity of oscillators is said to comprise a “meta-mass,” in that there is no direct interaction of the external environment and the oscillators, the presence of which is inferred in an observed non-Newtonian housing element behavior. For a class of meta-masses, for which the oscillators have more-or-less equal masses with resonances that densely fill a frequency band more-or-less uniformly, the non-Newtonian behavior is most transparently seen in a different “energetics,” i.e., the transfer of energy between the housing element and an external source, this occasioned by an inherently “transitory “internal energy transfer process. Encapsulating a large multiplicity of meta-masses in an ordinary material specimen is said to comprise a meta-material specimen, a somewhat different understanding in not having the direct interaction of each individual oscillator with every other individual oscillator obtain through the behavior of the material matrix. Constructed is a mathematical framework for quantifying limited observable system behavior while not accommodating all underlying physics, i.e., an “effective theory,” this a prerequisite for the design of meta-mass and meta-material mechanical/electrical devices.
The contribution of spectrum and tempo to auditory streaming of simple and compound “bols” in tabla rhythms
Authors: Singh Punita G.
Published: November 2013

Rhythms on the tabla, a north Indian percussion instrument, are generated by producing sounds on one or two drums separately or simultaneously to produce simple or compound “bols.” At high speeds, auditory stream segregation based on spectral properties of adjacent bols can create parallel perceptual layers that can be leveraged strategically by percussionists. This observed phenomenon was studied experimentally by constructing sequences of bols in which adjacent sounds shared different spectral regions. For example, the bols “ghe” and “tin,” which have very different spectra, were placed on either side of the compound bol “dhin,” which contains both “ghe” and “tin.” At a moderate tempo, the sequence is typically heard as a gallop rhythm. However, at quicker tempi, streaming occurs and components of the compound bol “dhin” group perceptually with their neighboring counterparts, to create parallel layers of pairs of “ghe,” “ghe” and “tin,” “tin”, instead of the galloping triple. Listeners identified when streaming took place as a function of the specific bols and tempi used. Spectral analyses of the bols indicated that perceptual segregation was indeed based on proximity of spectral loci. At high speeds, spectral differences are perceptually highlighted and facilitate the formation of auditory streams.
Measurements of coupled drumhead vibrations using electronic speckle-pattern interferometry
Authors: Worland Randy , Boe Benjamin
Published: November 2013

Many musical drums such as snare drums, tom toms, and bass drums consist of two membranes at opposite ends of a cylindrical shell. Striking one head causes both to vibrate, as their motions are coupled due to the enclosed air as well as the shell itself. An optical system consisting of two electronic speckle-pattern interferometers was constructed allowing operating deflection shapes of both heads to be viewed simultaneously while the drum is driven acoustically at a resonant frequency. This system allows the determination of the relative phases, orientations, and amplitudes of the vibrational patterns on the two heads. Previously reported results for coupled drumheads were verified and extended to include the effects of degenerate single membrane mode pairs that are split due to non-uniform tension in the heads. Examples of higher frequency coupled patterns are also shown. Parameters influencing the degree of coupling are described briefly and compared qualitatively with results from a finite element model.
Acoustical measurements and finite difference simulation of the West-African “talking drum"
Authors: Pfeifle Florian
Published: November 2013

A very iconic drum, commonly found in West-Africa, is the so called “talking drum.” It has a large geographic distribution, spreading several countries and ethnic groups. The characteristic feature of this unique instruments is the membrane, which can be tuned, through varying the tension of the membrane fixture, while playing. This effect can be utilized to play melodies and pitch-glides on the drum. West-African musicians use this effect to mimic speech patterns and speech melodies from tonal languages. This highly non-linear excitation of the drum leads to several questions regarding the acoustical properties of the instrument. The acoustical research of the drum include high-speed measurements of the drum-head to quantify the changing tension distribution over the membrane. Microphone array measurements, with 128 microphones, are applied to examine the radiation characteristics of the instrument. A special focus is put on the resonance frequencies of the enclosed air volume and the influence it has on the top and bottom membrane as well as the damping characteristics of the drum head. A physical model of the instrument, including a Kirchhoff-Carrier-like tension modulated, 2-dimensional, orthotropic, stiff membrane, coupled to a 3-dimensional air-volume is implemented and compared to the measurements.
Acoustic properties of carbon fiber in percussive instruments
Authors: Wion Alex , Vogt Rustin , Homen Patrick
Published: November 2013

With advancements in manufacturability and increasing accessibility of materials, composite materials are competing with traditional materials in the design and manufacturing of musical instruments. Specifically, in snare drum applications, carbon fiber encased in an epoxy matrix has been chosen for its physical properties of strength, durability, and weight as well as its psychoacoustic properties compared to wood. Through comparative data acquisition analysis, the acoustic properties of composite snare drum shells are examined against traditional wooden snare shells. By subjecting the shells to controlled audio frequencies, the sound energy response on the air medium outside of the shell was measured and compared to wooden shells. Experimental data were examined was compared to theoretical values found for carbon fiber.
Comparison and evaluation of physics-based outdoor sound propagation assessment schemes
Authors: Ronsse Lauren M. , Valente Dan
Published: November 2013

Evaluating the effectiveness of outdoor sound propagation assessment schemes using experimentally collected data is a complex task. Specifically, when the acoustic data collected assume non-Gaussian distributions with differing sample sizes per assigned class, traditional parametric statistical techniques may not be used. As an alternative, this research introduces an original cost function to evaluate and compare various methods aimed at defining acoustic propagation classes based on meteorological measurements. Class assignments in each scheme are based on the atmospheric stability, the strength of the vertical effective sound speed gradient, and the vertical effective sound speed profile. The acoustic data included in this analysis were generated by a high-energy impulsive source and gathered at source-to-receiver distances of 1, 2, 4, and 8 km. The results indicate that the assessment scheme based on the strength of the effective sound speed gradient most effectively classifies the peak level sound propagation sampled in temperate and desert climate conditions at these distances.
Variability in acoustic transmission loss over a rough water surface
Authors: Tollefsen Cristina , Pecknold Sean
Published: November 2013

Variability in the acoustic transmission loss of impulsive sounds propagating in the atmosphere over a rough water surface was measured over time scales of 1–2 h at a fixed range of 250 m. On two separate days (26 and 30 May 2012), a propane cannon source was deployed on the upper deck of a ship. Once per minute, the propane cannon fired volleys of four shots that were recorded on a receiver deployed on a small boat tethered upwind of the ship. Meteorological conditions and sea state were comparable on both days, resulting in similar observations for transmission loss: mean and standard deviation of 64 ± 5 dB (26 May) and 66 dB ± 4 dB (30 May). The variability in transmission loss was high, with minimum and maximum values of 48 and 75 dB (26 May) and 53 and 77 dB (30 May). The transmission loss measured throughout the experiment exceeded the 48 dB predicted by assuming spherical spreading, since the receiver was upwind of the source. Measured results are compared to transmission loss computed from a parabolic equation model using an ensemble of turbulence and rough sea surfaces estimated from the meteorological conditions on board the ship.
Source motion modeling for high-speed aircraft noise propagation
Authors: Tong Bao N. , Li Kai Ming
Published: November 2013

A continuous source motion model has been developed to represent a cruising aircraft traveling at high altitudes. The numerical implementation is based on the Lorentz transform (LT) and a Fast Field Program (FFP) formulation, which is used to compute the sound fields due to a monopole point source traversing in a horizontally stratified atmosphere parallel to a ground surface. To reduce the computational expenses, a one-dimensional LT-FFP is performed to obtain the pressure time-history for overhead flight conditions. The continuous source motion model is compared against a heuristic model which applies a Doppler shift to the stationary source sound field. A linear sound speed profile was selected to simplify the ray model implementation. A parametric study involving the source Mach number and source emission frequency has been performed in a variety of environmental conditions. The differences in the predicted maximum sound pressure levels between the two models can be as large as 9 dB under certain conditions. Numerical simulations indicate that low source emission frequencies (e.g., 50–300 Hz) combined with high source Mach numbers tend to result in larger discrepancies. The numerical simulations suggest the importance of including the effects of convective source amplification, especially, for turboprop aircraft noise propagation.
Passive acoustic remote sensing and anomalous infrasound propagation studies
Authors: Assink Jelle D. , Waxler Roger , Evers Laslo , Smets Pieter , Le Pichon Alexis , Blanc Elisabeth
Published: November 2013

In this talk, we will present recent work on various infrasound remote sensing studies. We will focus on bi-directional stratospheric ducting during a Sudden Stratospheric Warming (SSW) event and the associated infrasonic signature. We present infrasound data in which the described effect is captured with microbarom signals in the Mediterranean region. Microbarom source locations are modeled using operational ocean wave models. The modeling reveals a previously unidentified microbarom source region in the Eastern Mediterranean besides the more typical microbarom source region in the Atlantic Ocean. This work illustrates that the classic paradigm of a unidirectional stratospheric duct for infrasound propagation can be broken during a SSW event. Furthermore, we will present a case study in which the influence of atmospheric dynamics on infrasound propagation is studied. We make use of over 6 years of nearly continuous volcanic infrasound recordings from Mount Etna, Italy (37 N) that are available through the Atmospheric dynamics Research InfraStructure in Europe (ARISE) network. The infrasound observables are compared to theoretical estimates obtained from propagation modeling using existing European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric databases. While a good agreement is often found, we also report on significant discrepancies around the equinox period and during intervals during which anomalous detections occur during the winter.
Refraction of impulsive signals by a mountain slope
Authors: Waxler Roger M. , Velea Doru
Published: November 2013

As part of a recent experiment on signals from blast waves, it was possible to instrument a mountain slope to the east of the source locations. Four infrasound sensors were deployed about 1 km apart from the base of the mountain up. In addition, infrasound sensors were deployed close to the mountain peak, and then along a ridge extending to the east at roughly constant altitude. It was observed that signals developed a long, low frequency tail as they propagated up the slope. Data and theoretical analyses will be presented.
On the interaction of infrasonic waves with internal gravity waves perturbations
Authors: Lalande Jean-Marie , Waxler Roger , Lonzaga Joel
Published: November 2013

Infrasonic waves propagate at long range through atmospheric ducts resulting from the stratification of atmospheric properties. These ducts are characterized by their spatio-temporal variability. Hence, infrasonic waves integrate atmospheric information along their propagation paths. In order to study infrasonic wave propagation, we resort to atmospheric specification combining Numerical Weather Prediction and climatological models. However, due to the lack of observations, these models fail to describe small scale variability such as perturbations associated to the presence of internal gravity waves. These waves play an important role in the atmospheric dynamic by transferring momentum to the mean flow at critical levels and at wave-breaking altitudes. In this study we intend to describe the interaction of infrasonic waves with internal gravity waves in order to understand the long-tail behavior observed in infrasound broadband signals. We developed a model for the propagation of internal waves used to generate realistic perturbations of the background atmospheric states. By using a linear full-wave model of infrasound propagation, our goal is to ultimately relate infrasound characteristics to internal waves properties.
An exact solution of a Burgers' equation governing the nonlinear propagation of infrasound in a range-dependent, windy atmosphere
Authors: Lonzaga Joel B. , Waxler Roger
Published: November 2013

We present the derivation of an exact solution of an inviscid Burgers' equation that governs the nonlinear propagation of infrasound in a range-dependent, windy atmosphere with arbitrary sound speed, wind speed, and density profiles. The Burgers' equation is a reduced form of a nonlinear transport equation obtained using weakly, nonlinear ray theory. The solution extends known solutions for a homogeneous, windless medium to include the effects of wind and the inhomogeneity in the properties of the atmosphere. Analytical expressions for the shock velocity and period lengthening are readily obtained from the solution. The exact solution is used to validate our numerical algorithm which uses a spectral method to integrate the Burgers' equation. These models are compared with observed infrasound arrivals that clearly demonstrate nonlinear pulse steepening and stretching while propagating in the upper atmosphere.
Encoding of amplitude modulation upon interference in remote frequency regions
Authors: Shen Yi , Richards Virginia M.
Published: November 2013

The modulation detection threshold for a sinusoidally amplitude modulated target tone was measured in the presence of another amplitude modulated interference tone. The interferer had a carrier frequency of 700 Hz and a modulation rate of 40 Hz. The target carrier frequency was 1300 Hz, and its modulation rate was 23, 33, 43, 63, and 80 Hz in separate conditions. During the psychophysical experiment, the auditory frequency following response (FFR) phase-locked to the 700-Hz carrier and the auditory steady-state response (ASSR) phase locked to the 40-Hz modulator were recorded. It was hypothesized that when greater interference occurs (when the interferer and target had closer modulation rates), the neural representation to the interferer might be enhanced or suppressed to a lesser degree. Neither the FFR nor ASSR demonstrated dependency on the target modulation rate, and no significant correlation was found between the behavioral and these two types of physiological measures. Results suggest the possibility that the modulation detection interference might originate from a location that is more central to the neural structures that give rise to FFR and the 40-Hz ASSR.
Division of processing resources in auditory judgments
Authors: Gallun Frederick J. , Bonnel Anne-Marie , Hafter Ervin R.
Published: November 2013

The attention operating characteristic (AOC) displays joint performance in a dual-task paradigm. Sampling theory allows the AOC to be used to distinguish two tasks that share resources from two tasks that call upon independent resources. Work in the Hafter lab over the past twenty years has examined the division of resources from several different perspectives. This talk will review data on intensity discrimination and identification showing that “easier” tasks can cause dual-task costs, while “harder” tasks can have no costs associated with the dual-task. Recent data on intensity discrimination and identification will be examined in the context of the division of processing resources, showing that the costs of sharing resources can increase with age of the listener. Finally, suggestions will be made for ways in which the current enthusiasm for the dual-task paradigm in clinical research can be used to improve our theoretical understanding of attention and memory as well as demonstrating the effects of various impairments and prostheses.
Lateralization, discrimination, detection, and Ervin
Authors: Stern Richard M.
Published: November 2013

Erv Hafter’s early work focused on the development of a comprehensive understanding of the binaural system, combining a characterization of the subjective phenomena associated with binaural lateralization with the results of objective experiments measuring interaural discrimination and binaural detection. To a large extent, this author’s attempts to characterize a broad range of auditory phenomena based on a Jeffress-Colburn cross-correlation-based model can be viewed as a reformulation of the stimulus-based lateralization model that Hafter developed to provide a unified theoretical framework for his own findings. Erv Hafter has a gift both for designing clever and revealing experimental stimuli and paradigms, as well as for developing provocative interpretations of his experimental results. This paper will discuss a selection of complex binaural phenomena revealed by Erv’s research in the context of their impact on contemporary theories of binaural interaction, as well as their impact on computational models of speech processing for robust speech recognition. [Work supported by DARPA and Cisco Research.]
On the temporal weighting of binaural cues: precedence effects, rate limitations, and binaural adaptation
Authors: Stecker G. Christopher , Brown Andrew D. , Diedeisch Anna C. , Bibee Jacqueline M.
Published: November 2013

Over the course of three decades, Erv Hafter and his colleagues have investigated the relative effectiveness of binaural cues carried by different temporal portions of brief, mainly, high-frequency, stimuli. Those studies pioneered the use of filtered impulse trains (avoiding many limitations of sinusoidal amplitude modulation, and presaging the use of “transposed tones” for delivering envelope ITD), and revealed rate-limited processing of post-onset cues (Hafter and Dye 1983). Careful modeling of the effects on both ITD and ILD later led Hafter et al. (1988) to propose a pre-binaural origin for this binaural adaptation, and Hafter and Buell (1990) to present a simple quantitative model of monotonic, onset-triggered reduction of cue effectiveness over time. Erv’s later students adopted observer-weighting paradigms to more directly measure the influence of each click in a train (Saberi 1996, Stecker and Hafter 2001), revealing some important and cue-dependent non-monotonicites. Our own work has continued this line of research, most recently investigating the temporal weighting of binaural cues in lower-frequency sounds. Consistent with a large body of Hafter’s work, the results reveal an important temporal asymmetry in the effectiveness of binaural cues at both low and high frequencies and a key role for pre-binaural mechanisms. [Work supported by R03DC009482, R01DC011548.]
Improvement of footfall vibration of concrete floors: Two case studies
Authors: Gendreau Michael , Amick Hal
Published: November 2013

It is sometimes necessary to improve the footfall performance of an existing concrete floor in a manufacturing facility, as is the case when the vibration criterion changes because of new technology. The paper examines two case studies in which the floors were modified simply by placement of an additional concrete slab atop the existing slab. This approach has some drawbacks, most notably the additional weight, which must be accommodated by the available framing and foundation capacity. Measured data are presented which illustrate the changes in structural properties and footfall performance.
Visualization of the laryngeal muscles with high-quality magnetic resonance imaging
Authors: Takano Sayoko , Honda Kiyoshi
Published: November 2013

The larynx is the organ to adjust voice in speech important for controlling voice phonation, and the tensions of the vocal folds cord is controlled by the relative positions among the thyroid, arytenoid, and cricoid cartilages. Magnetic resonance images (MRI) have been employed to observe the positions of those cartilages, while however, visualizing the laryngeal muscles for activating moving those cartilages is still difficult with the conventional MRI. This study aims to visualize and identify the laryngeal muscles based on the composition of the three different sets of gray-scale MRI data into red, green, and blue channels, namely RGB-MRI. The types of imaging parameters image variations are field-echo opposed-phase (FE(op)), spin-echo proton density weighted (SE(PDw)), and spin-echo T1 weighted (SE(T1w)). This method for image composition helps usidentifying could reveal the location of the muscles in the laryngeal region in vivo. We have successfully identified the sternohyoid muscle, thyrohyoid muscle, lateral thyroarytenoid muscle, cricothyroid muscle, stenrocleidmustoid muscle, omohyoid muscle, and inferior constrictor muscles. The RGB-MRI could give further provide anatomical information of the larynx, especially about the muscle location and its deformation involved in on speech mechanisms, which will be useful for both research experts and beginners.
Motor control primitives arising from a dynamical systems model of vocal tract articulation
Authors: Ramanarayanan Vikram , Goldstein Louis , Narayanan Shrikanth
Published: November 2013

We have previously presented a computational approach to derive interpretable movement primitives from speech articulation data using a convolutive Nonnegative Matrix Factorization with sparseness constraints (cNMFsc) technique (Ramanarayanan et al., Interspeech 2011; Ramanarayanan et al., J. Acoust. Soc. Am. 134(2), in press). However, it is not clear whether finding such a dictionary of primitives can be useful for speech motor control, particularly in finding a low-dimensional subspace for such control. In this paper, we examine this possibility in two steps. First, we use the iterative Linear Quadratic Gaussian (iLQG) algorithm to derive a set of control inputs to a dynamical systems model of the vocal tract that produces a desired movement sequence. Second, we use the cNMFsc algorithm to find a small dictionary of control input “primitives'' that can be used to drive said dynamical systems model of the vocal tract to produce the desired range of articulatory movement. We show, using both qualitative and quantitative evaluation on synthetic data produced by an articulatory synthesizer, that such a method can be used to derive a small number of control primitives that produce linguistically interpretable and ecologically valid movements. Such a primitives-based framework could help inform theories of speech motor control and coordination.
Coprime arrays in the context of compressive sensing
Authors: Pyzdek Andrew T. , Culver R. Lee
Published: November 2013

Arising naturally from the formalism of coarrays, coprime arrays offer a means of achieving sparsity along an array while maintaining certain measures of performance. This configuration offers benefits over traditional configurations for large aperture towed arrays in the ocean environment, but shallow water propagation complicates the wide sense stationarity assumption that is essential to proper application of coarray concepts. Compressive sensing techniques allow for the reconstruction of generalized signals which are sparse on some known basis. Existing literature has shown the connection between compressive sensing and random arrays, drawing direct parallels between the results and methods that arose independently in both fields. Compressive sensing may offer an alternative understanding of coprime arrays, which is independent of wide sense stationarity, and thus applicable to shallow water environments. Coprime arrays will be considered in the context of compressive sensing. It will be discussed if the measurement matrices that arise from this array geometry might possess properties necessary for compressive sensing reconstruction to function, such as the Restricted Isometry Property. [This research was supported by the Applied Research Laboratory, at the Pennsylvania State University through the Eric Walker Graduate Assistantship Program.]
Beam-patterns of a collocated unit of three orthogonally oriented second-order directional sensors
Authors: Wong Kainam T. , Song Yang
Published: November 2013

A microphone or a hydrophone measures the incident acoustic wavefield as a scalar field of pressure. Underlying this pressure scalar is the particle-velocity vector, which constitutes the spatial gradient of the wavefield. Each Cartesian component of this gradient vector may be directly measured (without computing any spatial derivative) by a particle-velocity sensor aligned in parallel to that Cartesian coordinate. The entire 3 × 1 gradient vector may be measured at any point in space, using three such particle-velocity sensors, collocated but orthogonally oriented among themselves. Such a collocated triad has an array manifold independent of signal frequency, thus uncoupling azimuth-elevation beamforming from the frequency-dimension. This triad’s beam-pattern has already been investigated by Wong and Chi ["Beam patterns of an underwater acoustic vector hydrophone located away from any reflecting boundary,” IEEE J. Ocean. Eng. 27(3), 628–637 (2002)]. While the particle-velocity sensor measures the first-order spatial derivative of the pressure field, a second-order spatial derivative of the pressure-field could likewise be defined and be measured by a “second-order directional sensor” that would have sharper directivity. This paper follows up that investigation, but now for second-order directional sensors.
Objective functions incorporating various norms for the three-dimensional sound manipulation
Authors: Kim Yang-Hann , Choi Jung-Woo , Song Min-Ho
Published: November 2013

Using many array speakers to manipulate sound in space and time requires proper objective functions that can determine the array speakers' magnitude and phase relationships. Mathematically speaking, this means that magnitude and phase of each speaker have to be determined in such a way that certain designed objective functions can be minimized or maximized. The most popular way to define the objective function is to utilize the form of L2 norm, but it is also likely possible to utilize L1 norm to decide corresponding array speakers magnitudes and phases. Depending on what we would like to manipulate in space and time, the objective functions can be selected: they can be, for example, energy in a selected zone, or contrast of sound energy, for the case of L2 norm. In this paper, we study how those functions affect the performance of sound manipulation in terms of array parameters and effectiveness of 3D sound manipulation.
What is the surface tension at a bubble wall?
Authors: Leighton Tim , Zhu Mengyang , Birkin Peter
Published: November 2013

The surface tension on a bubble wall frequently arises in models of single bubbles and is an influential parameter when assessing many important processes. These range from the global transfer of mass, momentum, and energy between the oceans and the atmosphere, to the efficacy of microbubbles for clinical diagnosis and therapy. However, the simplicity by which surface tension appears in formulations belies the complexity of the process. For example, the distribution of chemical species or dopants may be uneven over the wall of a single bubble, the translation of a bubble relative to the bulk liquid may change the chemical loading over time, and the pulsation and shape changes of bubbles perturb the distribution of a dopant on the bubble wall. This paper reports on an experimental technique for estimating one measure of the surface tension at the gas/liquid boundary of a bubble.
The influence of temperature on bubble formation under breaking waves
Authors: Czerski Helen
Published: November 2013

The bubble plumes generated by breaking waves have a complex structure that is highly dependent on the local environment. These temporary bubble populations have a strong influence on many processes at the air-sea interface, for example, air-sea gas transfer, aerosol production, sound transmission, and optical absorption. To quantify the importance of the bubble plume, two things are required: the state of the initial bubble plume and an understanding of the longer-term plume evolution. This paper focuses on the formation of the initial bubble plume. I’ll present evidence showing the effect of temperature on the fragmentation of single bubbles in the laboratory. These results imply that changing the water temperature has consequences for ocean bubble plume structure, bubble size distribution, and whole bubble plume acoustics, and these will be discussed.
Underwater sound radiated by bubbles released by melting glacier ice
Authors: Lee Kevin M. , Wilson Preston S. , Pettit Erin C.
Published: November 2013

Passive acoustics monitoring techniques have been examined as a method to remotely sense activity of glacier ice near the ice-ocean boundary [Ann. Glaciol. 53, 113–121 (2012)]. Sound from glacier calving events and the resultant breaking and bobbing of the ice after impact with the water ranges from infrasound (<10 Hz), to low-frequency (100 Hz—1 kHz), to higher frequency sound (>10 kHz) generated by breaking tsunamis and seiches after impact. Bubbles are known to form within ice during glacier formation and can be released from glaciers as they undergo submarine melting. Due to the possibility of high internal bubble pressure, this release can occur in the form of jetting or squirting events. Signals hypothesized to be from bubbles being released from melting glacier ice were measured in Unakwik Inlet and Icy Bay, Alaska using passive autonomous hydrophone moorings and near-surface recordings in the 1 kHz—3 kHz frequency range. To temporally and spatially correlate such acoustic emissions with bubble activity, a set of laboratory measurements was performed using small samples of glacier ice, and acoustic emission was positively correlated with bubble release. Taken together, these measurements support the use of passive acoustics to monitor marine glacier ice melt.
Time and frequency analysis of air bubbles injected underwater
Authors: Lohrasbipeydeh Hannan , Dakin Tom , Gulliver T. Aaron
Published: November 2013

The acoustic signal generated by vibrating air bubbles injected in water allows for the passive detection of underwater sources such as divers and gas leaking from pipes. In this paper, an experimental analysis of the time and frequency characteristics of these signals is presented. The decaying acoustic signal of a single bubble created by nozzles of different diameters is described and extended to a train of bubbles from an array of nozzles. The oscillatory motion of the bubble surface generates an acoustic signal that has a damped sinusoidal characteristic. The spectrum of this waveform has a fundamental frequency and several harmonics. Therefore, the effect of ambient noise can be suppressed using a suitable band pass filter with a center frequency equal to the bubble fundamental frequency. It is shown that the acoustic signal generated by these bubbles can be utilized for passive detection and remote sensing (including depth estimation). Experimental data from a Saanich inlet experiment is analyzed to obtain realistic results. These results are compared with the theoretical analysis.
The limits of using closed-cell foam as a pressure release condition when dealing with underwater acoustics
Authors: Dolder Craig N. , Wilson Preston S.
Published: November 2013

Closed-cell foams are frequently used in both the research and industry communities to provide a pressure release condition for underwater sound. In practice, closed-cell foams can effectively imitate a pressure release condition even if the thickness of the foam is as small as 1/60th the wavelength of the sound in water, however these conditions start to break down as the sound speed in water is reduced. The presence of even a small volume fraction of bubbles can cause the sound speed to drop in such a way that the water can couple with the closed-cell foam and prevent the interface from providing a pressure release condition. Measurements made in an acoustic resonator are used to show how the idealized system breaks down. [This work was supported by the Office of Naval Research.]
On the shoulders of giants: Remembering the contributions of Warren Blazier
Authors: Mahoney Robert F.
Published: November 2013

Gentleman, scholar, mentor, Warren Blazier exemplified all these roles in his career of six decades. Many of us who benefited from his research, his teaching, and especially from his unstinting and magnanimous instruction owe Warren a great deal. This brief talk will discuss some of the frontiers Warren established—and significantly advanced—as well as the lessons we beneficiaries learned from him. Many of these lessons extend well beyond the science of noise control and, we hope, can be passed on to our successors as well.
Warren Blazier's contributions to building acoustics, a manufacturer's perspective
Authors: Mason Norman
Published: November 2013

Warren Blazier and Norm Mason first met at York Borg-Warner’s Engineering Offices over 50 years ago; Warren was running their Acoustics Department. Warren moved on to Bolt Beranek Newman and then physically to San Francisco and the two remained great friends. Norm Mason consulted Warren on his theoretical understanding of Noise and Vibration Control and Warren was influential in the development of Mason Industries Architectural products. This paper will attempt to capture the highlights of Warren Blazier’s friendship with Mason Industries, Inc.
Lessons from the dean of noise control
Authors: Borzym Jim X.
Published: November 2013

Professorial, collegial, passionate, and gentlemanly, Warren E. Blazier, Jr., was admired in our profession as a top-level consultant and collaborator, and sometimes referred to as the “Dean” of noise control engineering. This presentation will highlight several technical topics incorporated in project consultations by Warren Blazier. Topics include duct plena, fan efficiency, structural resonance, floated floors, and unusual projects. Comments and personal insights presented by a mentee and collaborator of Warren Blazer's during the post-BBN decade 1986 through 1996.
Warren Blazier and his contributions to noise rating criteria
Authors: Roy Kenneth P.
Published: November 2013

Warren Blazier was well known for his work with sound and vibration in mechanical systems, e.g., HVAC equipment. As such, he was particularly active at ASHRAE in addition to the ASA meetings. Although I was always focused more on the “room acoustics” side of the design, I none-the-less offered to help edit the 1999 ASHRAE Handbook chapter 43 with Warren and Chuck Ebbing. This section dealt with “Indoor Sound Criteria,” and what an eye opening event this turned out to be. You might say that I jumped into the fire as there was an ongoing “tug-of-war” over which rating system should be adopted to describe background noise in buildings from mechanical systems. NC, RC, RC mark II, NCB … several of these had been used up to this point and lots of controversy existed as to what to include in the re-write. A somewhat historic special meeting of ASHRAE TC2.6 was held in Boston on the evening of Sunday 27 June 1997 from 3:30 to 6:30 pm where this was discussed to resolve the issue. Both Warren and Leo Beranek were asked to make presentations on the merits of the competing approaches. And this is what was decided!!
Cyclical patterns in long-term bioacoustic data
Authors: Baumann-Pickering Simone , Roch Marie A. , Širović Ana , Hildebrand John A.
Published: November 2013

Cyclical patterns in biological systems occur from small to large temporal scales, and these cycles are also reflected in acoustic data. To interpret long-term patterns appropriately, knowledge about natural cycles is crucial. We will show examples of diel, lunar, and seasonal patterns for a variety of species from invertebrates to vertebrates. The observed patterns are likely driven by intra-specific communication, or prey behavior and availability, which in turn can be related to large scale and long-term environmental modulation. Absence of acoustic signals does not necessarily indicate absence of the caller but the calling behavior may be limited to a certain time of the cycle period. In addition, various acoustical sources can complicate results. Patterns from abiotic and anthropogenic sources may mask or alter natural biological acoustic cycles. Animals moving just outside of an acoustic recorder’s detection range may lead to misinterpretation of diel behavior. Effects of multi-annual or multi-decadal cycles are extremely difficult to investigate due to the long time series needed to take them into consideration.
Baleen whale calls in the Southern California Bight from 2009 to 2012
Authors: Sirovic Ana , Roch Marie A. , Baumann-Pickering Simone , Buccowich Jasmine , Debich Amanda , Johnson Sarah C. , Kerosky Sara M. , Roche Lauren K. , Wiggins Sean M. , Hildebrand John A.
Published: November 2013

Baleen whales are an important contributor to the Southern California Bight soundscape. Calls from some species only contribute seasonally, while others are part of the soundscape year-round, albeit at varying levels. Passive acoustic monitoring has been conducted at the U.S. Navy’s Southern California Offshore Range (SCORE) since 2009. Data were collected at two sites concurrently using High-frequency Acoustic Recording Packages (HARPs). Analysis in the low frequency band (10 Hz—1 kHz) has yielded results on the seasonal and interannual variation in the presence of calling blue (Balaenoptera musculus), fin (B. physalus), Bryde’s (B. edeni), and humpback whales (Megaptera novaeangliae). Calls of most species (blue, Bryde’s, and humpback whales) were only present during part of the year, indicating seasonal migration common for these species. On the contrary, fin whale calls were prevalent year-round, although the abundance of their 20 Hz calls tended to decrease in the summer. The link between the relative changes in interannual call abundance (i.e., soundscape contribution) and prevailing environmental conditions, such as the sea surface temperature and chlorophyll a, was investigated using the Tethys spatial-temporal database framework. These links can be important for understanding the year-to-year variation in soundscape.
Prospects for short-term and long-term passive acoustic monitoring of environmental change impact on marine mammals
Authors: Sidorovskaia Natalia , Ackleh Azmy S. , Tiemann Christopher O. , Ioup Juliette W. , Ioup George E.
Published: November 2013

The Littoral Acoustic Demonstration Center, LADC, a consortium of scientists from four Gulf state universities and the U.S. Navy, was begun in 2001 to study underwater noise and acoustic propagation, and the impact of human activities in the ocean on marine mammals, with emphasis on the Gulf of Mexico (GoM) region. LADC has a library of broadband passive acoustic data, collected by autonomous bottom-moored buoys, which sampled the GOM region ambient noise state, seismic airgun array emissions, and/or marine mammal activities six times during the last decade. LADC acoustic data represent an opportunity to study the short- and long-term effects of environmental changes on the marine mammal population. Environmental factors include baseline anthropogenic noise levels, passages of tropical storms, seismic exploration surveys in the area, and the 2010 Deepwater Horizon oil spill accident. The talk summarizes recent findings on the relationship between regional population dynamics of sperm and beaked whales and abrupt environmental changes with emphasis on the recent GoM oil spill. Statistically significant results of the study suggest a need for establishing consistent acoustic monitoring protocols in the oceanic areas of current or potential industrial activities. [Past data acquisitions were supported by ONR, SPAWAR, JIP, NSF, and Greenpeace.]
Acoustic monitoring of breeding amphibians at Yosemite National Park and Point Reyes National Seashore
Authors: Kleeman Patrick , Fellers Gary , Halstead Brian
Published: November 2013

The calling behavior of frogs and toads at breeding sites lends itself to acoustic monitoring of these amphibian populations. We are using Automated Recording Devices (ARD) at two National Park units in California, Yosemite National Park and Point Reyes National Seashore, to monitor the breeding efforts of amphibians by recording their calls. We are monitoring both common species (Pacific chorus frogs, Pseudacris regilla, occurs in both parks) and imperiled species (Yosemite toad, Anaxyrus canorus, Yosemite; California red-legged frog, Rana draytonii, Point Reyes) to investigate whether breeding phenology will shift with changing climatic conditions. The use of ARD is also providing a more complete picture of the diel calling patterns of these species, and how some species are partitioning their acoustical environment by frequency and time in order to breed successfully while surrounded by noisy neighbors. Information gathered through acoustic monitoring is very valuable for conserving rare amphibians and ensuring that common species remain common.
Spatiotemporal variability in coral reef soundscapes in St. John, U.S. Virgin Islands
Authors: Kaplan Maxwell B. , Mooney T. Aran , Partan Jim
Published: November 2013

Passive acoustic measurements of coral reef “soundscapes” can be an effective way of tracking biological activity and may help assess community-level biotic diversity. While a reef soundscape may vary both temporally and spatially, this variability is often not well understood. To investigate this, we deployed multiple digital acoustic recorders (DMONs) for both short- (24-h) and long-term (4 months) investigations at three patch reefs that varied in coral cover (low, intermediate, and high levels) in the U.S. Virgin Islands National Park (sample rate: 120 kHz). The short-term investigation consisted of four continuously recording instruments spaced at ~20 m intervals. Long-term measures included two recorders per reef on a duty cycle of 2.5 min/2 h. Fish and coral diversity, ambient light intensity, temperature, and salinity were also measured. Results indicate diel patterns in snapping shrimp signals (dominant energy between 2.5 and 20 kHz) with peaks at dusk and dawn. Sound pressure level (SPL) of the snapping shrimp band varied spatially within and among reefs, with higher maximum SPL at reefs with low and intermediate coral cover. However, within-reef SPL variability was lowest at the site with high coral cover. Temporal patterns in snapping shrimp acoustic activity were correlated within and among all three reefs.
The ambient acoustic environments at two locations in Laguna San Ignacio, Baja, Mexico
Authors: Seger Kerri , Thode Aaron M. , Swartz Steven , Urban Jorge
Published: November 2013

Each winter gray whales (Eschrichtius robustus) breed and calve in Laguna San Ignacio, with the lagoon's northern section more heavily used by mothers rearing calves. The southern section of the lagoon is open to milling and ecotourism traffic, while the northern section is restricted to vessel transits only. Ambient acoustic data from autonomous underwater recorders have been collected between 2008 and 2013 at Punta Piedra (southern section) and Camp Kuyima (northern section). Multiple sources of acoustic sound exist in the lagoon, including tidal flows, fish chorusing, gray whale vocalizations, snapping shrimp, daily land/sea breezes, and panga activity. Here the cumulative distributions of rms sound pressure levels from all deployments during daytime and nighttime are presented for several frequency bands that represent contributions from the varying source mechanisms. Since concurrent data from both restricted (northern) and unrestricted (southern) sections exist, comparing sound level distributions between sites can provide insight into the relative contributions of various mechanisms to the overall ambient noise environment. These data have established a baseline for monitoring trends and changes in acoustic environments of the lagoon in anticipation of future tourist development. [Work sponsored by LSIESP and Ocean Foundation.]
Soundscapes from hydrophone stations in the comprehensive nuclear-test-ban treaty organisation's international monitoring system hydroacoustic network
Authors: Prior Mark K. , Brown David
Published: November 2013

The Comprehensive Nuclear-Test-Ban Treaty Organisation operates a global network of sensors that includes cabled sound-channel hydrophones in the Atlantic, Pacific and Indian Oceans. Hydrophones are deployed in groups of three, known as triads, so that the arrival times and azimuths of signals can be obtained. Data are recorded at frequencies up to 100 Hz with continuous acquisition and data relay via satellite connection to CTBTO’s International Data Centre. Signals from distant earthquakes, underwater explosions, marine mammals and ice-breaking are routinely detected and an extensive archive has been built up over the last decade. To understand sensor detection performance, high-level summaries of noise properties are required to establish the “acoustic context’ for each station. These “soundscapes” allow the identification of source types that dominate in specific frequency bands. Examples signals are illustrated and information regarding the sources of persistent signals is extracted.
The marine soundscape of the Fram Strait
Authors: Sagen Hanne , Tengesdal Hans Kristian , Babiker Mohamed , Tollefsen Dag
Published: November 2013

The marine soundscape of the Fram Strait has been subject to investigations since the mid 1980’s. Increasing interest in Arctic operations has initiated a recent series of acoustic experiments that includes synoptic ambient noise measurements in the Marginal Ice Zone conducted over the years 2010–2012. This presentation will give an overview of these experiments, then focus on results from measurements made with sonobuoys under varying ice and environmental conditions in the MIZ. Noise spectra (20 Hz—2 kHz) are presented, discussed, and compared with historical data from 1985 to 1987. Spectra are categorized by environmental parameters including wind force and direction as derived from numerical models, ice concentration derived from satellite images, ocean wave properties from a coupled ice-ocean prediction model, and sound propagation conditions inferred from the ice-ocean model. The contributions to this soundscape that will be quantified and discussed include open-ocean wind-generated noise, ice floe collision, marine mammals, and seismic exploration activity.