bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustics curriculum for architectural engineers
Authors: Muehleisen Ralph T.
Published: October 2013

As building design and technology increase in complexity, the need to consider acoustics in the design also increases. For decades, architects have relied on engineers for the design of structural, mechanical, electrical, and lighting systems of buildings, and are increasingly relying on engineers for the design of high-efficiency building enclosures and natural lighting systems. At the same time, building systems have become increasingly integrated, and good design of the building systems requires a very interdisciplinary education. These needs have given rise to the formal discipline known as architectural engineering (AE). With education in architecture, structures, building systems, and construction management, the architectural engineer is uniquely qualified to begin a career as an acoustical consultant. There are now over a dozen ABET-accredited AE programs throughout the country and most offer at least some education in architectural acoustics and noise control. In this talk, the requirements of an acoustics education for architectural engineers are outlined and the curriculum of several AE programs is presented.
The absorption of sound on Mars using the direct simulation Monte Carlo
Authors: Hanford Amanda D. , Long Lyle N.
Published: October 2013

The physical properties that govern the absorption of sound on Mars are very similar to those on Earth: classical losses associated with the transfer of acoustic energy into heat, and relaxation losses associated with the redistribution of internal energy of molecules. The difference in molecular composition between Earth and Mars as well as the lower atmospheric pressure on Mars results in larger values for the absorption coefficient on Mars. The direct simulation Monte Carlo (DSMC) method is the simulation tool used for modeling sound propagation in the Martian atmosphere. DSMC describes gas dynamics through direct physical modeling of particle motions and collisions. DSMC is based on the kinetic theory of gas dynamics, where representative particles are followed as they move and collide with other particles. The validity of DSMC for the entire range of Knudsen numbers (Kn), where Kn is defined as the mean free path divided by the wavelength, allows for the exploration of sound propagation in the Martian atmosphere for all values of Kn. Successful application of the DSMC method to acoustic waves in the Martian atmosphere, including the details of molecular relaxation in gas mixtures, will be shown. [Work supported by NASA.]
Upward propagation of nonlinear sound and magnetic sound in the atmosphere
Authors: Ostrovsky Lev
Published: October 2013

As is known, even relatively weak ground-level perturbations (earthquakes, tsunami, explosions) may cause very significant displacements in upper atmospheric layers where the gas density is small. It results in shock formation and subsequent rapid dissipation of wave energy. This presentation deals with the upward propagation of a short, finite-amplitude wave in atmosphere with exponentially decreasing density, including areas where the magnetic pressure prevails, and the acoustic energy is transformed to that of fast and/or slow magnetic sound. The height of shock formation is determined, and the wave attenuation due to shocks is described. Propagation from a localized source is also discussed. Some estimates are given.
The coherence function of a sound field propagating in a turbulent atmosphere
Authors: Ostashev Vladimir E. , Collier Sandra L. , Wilson D. Keith
Published: October 2013

The coherence function of a sound field propagating through an atmosphere with temperature and wind velocity fluctuations is important for many practical applications involving microphone arrays. In the literature, the transverse coherence function has been studied in detail, when acoustic sensors are located in a plane perpendicular to the sound propagation path. In this paper, for the case of line-of-sight sound propagation, a closed-form expression for the coherence function of a plane wave is derived for arbitrary location of acoustic sensors. Using this expression, for some limiting cases simple formulas for the coherence function are obtained which are valid for arbitrary spectra of turbulence. Furthermore, the coherence function is calculated and analyzed in detail for the Gaussian and von Kármán spectra of temperature and wind velocity fluctuations. In particular, the longitudinal coherence radius, when acoustic sensors are located along the sound propagation path, is calculated. It is also shown that contours of the coherence radius are elongated perpendicular to this path for relatively small propagation distances, and along it for large distances.
Comparison of high-frequency measurements of blast wave propagation to computational model predictions
Authors: Loubeau Alexandra , Sparrow Victor W.
Published: October 2013

In November 2005, the latest in a series of blast wave propagation experiments was conducted with the U.S. Army. Blast waveforms measured with a wideband microphone [W. M. Wright, ONR Report NR-384-321 (1971)] had shorter rise times than those captured with conventional1/8 -in. microphones. This indicates that the 1/8-in. microphone setup did not have the high-frequency bandwidth needed to capture such short rise times. The trend observed is that nonlinear effects steepen the waveform, thereby decreasing the shock rise time, up to a range of 50 m. At 100 m, the rise times had increased slightly, but they were still shorter than they were at 25 m. The experimental results are compared to predictions from a computational model. The model, based on the Pestorius/Anderson hybrid time-frequency domain algorithm, accounts for nonlinearity, geometrical spreading, thermoviscous absorption, and absorption and dispersion due to molecular relaxation. It is found that the model predicts shorter rise times than what was measured with the wideband microphone, but the rise-time variation with range is similar. Atmospheric turbulence present in the experiments, but not accounted for in the model, is a likely cause for the difference in rise times. [Work supported by U.S. Army ERDC CERL.]
Induced loudness reduction as a function of frequency separation
Authors: Marozeau Jeremy P. , Epstein Michael , Florentine Mary
Published: October 2013

When a loud tone (inducer tone) precedes a softer tone (test tone), the loud tone can reduce the loudness of the softer tone. This phenomenon is called induced loudness reduction (ILR). The amount of ILR is greatest when the inducer tone and the test tone are presented at the same frequency. As the difference in frequency between the two increases, the amount of ILR decreases [Marks L. E., J. Exp. Psychol. Hum. Percept. Perform. 20, 382–396 (1994)]. However, the exact course of this decrease with increasing frequency separation has not been thoroughly tested. In this experiment, the amount of ILR produced by a 2.5-kHz 80-dB-SPL inducer was measured from 800 Hz to 6 kHz using a frequency-sweeping test tone. Nine normal-hearing listeners matched the loudness of the test tone to a 70-dB-SPL 500-Hz tone using a tracking procedure. Average results show a maximum amount of ILR between 2.5 and 3 kHz, with a loudness reduction equivalent to 12 dB. This amount decreases with frequency separation, but is still significant when the frequency of the test tone is between 1.5 and 4.5 kHz, corresponding to more than nine critical bands. [Work supported by NIH/NIDCD Grant R01DC02241.]
Increasing cross-talk immunity in simultaneous multiple acoustic sources measurements using coded signals
Authors: Li Shu , Xiang Ning
Published: October 2013

Maximal-length sequences (MLS) and related signals demonstrate excellent correlation properties including a pulselike autocorrelation function and a relatively smaller-valued cross-correlation function. They have been increasingly applied in acoustical measurements [Xiang et al., J. Acoust. Soc. Am. 117, 1889–1894 (2005)]. Recent work employs specialized FFT-based algorithm [Daigle and Xiang, J. Acoust. Soc. Am. 119, 330–335 (2006)] using MLS-related signals into simultaneous multiple acoustic sources measurements (SMASM). The resulting impulse responses of acoustic channels, however, suffer from cross-talk noise. To enhance cross-talk immunity, this paper proposes an algorithm using pseudoinverse algorithm to improve signal-to-noise ratio in the SMASM. This proposed algorithm applies specialized correlation method and pseudoinverse processing to implement acoustic measurements for the SMASM technique. This paper discusses both simulation and experimental results of the SMASM with the pseudoinverse algorithm to demonstrate considerable improvements in signal-to-noise ratio. This paper also evaluates the efficiency of pseudoinverse algorithm for the increased cross-talk immunity.
Detection of phase-coupled noises in the ocean
Authors: Supriya M. H. , Pillai P. R. Saseendran
Published: October 2013

Estimates of power spectral density are being used in a variety of signal processing applications. For the precise characterization of certain noise sources in the ocean, the phase blind power spectral estimation does not yield the required result. Estimates of the bispectrum and bicoherence have been found useful in detecting non-Gaussianity and nonlinearity, in system identification, as well as transient signals. The power spectrum, in general, fails to quantify any nonlinear interactions between the component frequencies. Such interactions induced by second-order nonlinearities give rise to certain phase relations called quadratic phase coupling (QPC). Bispectral analysis, which is based on the third-order cumulant sequence of the signal, can reveal the presence of as well as provide a measure to quantify such phase couplings. Bispectral analyses of various noise data records collected from different ocean noise sources have been carried out and it is seen that the bispectrum is not identically zero, implying the non Gaussian nature of the noise data. This paper presents the bispectral estimation approach for identifying the nonlinearities in the underwater noise-generating mechanisms as well as detecting the presence of quadratic phase couplings, thus leading to the identification of the noise sources.
Modeling nonlinear acoustics in shallow water
Authors: McDonald B. Edward , Kuperman William A.
Published: October 2013

Lessons learned in modeling nonlinear acoustics and weak shock propagation in deep water are helpful in application to shallow water (mine countermeasures in particular), but the medium is much more complicated. Numerous improvements are needed; Joe Blue’s work touched on several of them. First is the need to treat higher propagation angles. Second is the presence of bubbles near the surface and possibly in the bottom. Finally, there are problems introduced by nonlinear propagation in granular sediments. These include greatly increased nonlinearity parameter and time-domain formulation of frequency—linear attenuation. Recent progress in the application of the NPE model [McDonald and Kuperman, ‘‘Time domain formulation for pulse propagation including nonlinear behavior at acoustic,’’ J. Acoust. Soc. Am. 81, 1406–1417 (1987)] to mine countermeasures will be outlined. [Work supported by the Office of Naval Research.]
A dolphin acoustic tapetum?
Authors: Ridgway Sam , Blankenship Brad , Houser Dorian , Carder Don , Hoh Carl
Published: October 2013

Many mammals including dogs, cats, deer, and dolphins, but not humans, have a reflective membrane at the back of the eye. This tapetum lucidum affords the light-sensitive retinal cells a second chance for photon-photoreceptor stimulation, enhancing low light visual sensitivity. Dissection of preserved specimens and computed tomography (CT) scans of live dolphins have shown prominent air cavities around the ear, especially medial and posterior. Histologic evaluation of peri-otic tissue revealed epithelial lined air sinuses and erectile tissue containing nerves, ganglia, smooth muscle bands, vascular spaces, and periarterial venous networks. Two dolphins were trained to periodically recognize and respond to a 1.5-s, 70-kHz target tone. In three experiments, 20 target tones were presented through a jaw phone after injection of 18 Fluro-deoxy-d-glucose (FDG). Subsequent positron emission tomography (PET) scans revealed that the tone, to which the dolphin had responded and been rewarded numerous times in the past, elicited a marked increase in metabolism in the erectile tissue medial to the stimulated ear but not the contralateral ear. Tissue around reflective air sinuses medial to the ear become active with acoustic stimulation, suggesting that sinus air may be shaped so as to provide an ‘‘acoustic tapetum’’ for dolphins.
Effects on fish of pile driving, wind turbines, and other sources
Authors: Hawkins Anthony
Published: October 2013

The sounds associated with construction work in the sea are reviewed. The installation of offshore oil and gas platforms, the mounting of offshore wind turbines on the seabed, the construction and renovation of harbors and piers, and the laying and trenching of pipelines and cables can be exceptionally noisy activities. The sounds associated with pile driving, in particular, have the potential to injure fish, induce hearing loss, and evoke avoidance reactions. The sound-pressure levels generated in water by these activities are generally measured, but many fish respond to particle motion rather than sound pressure. Measurements of particle motion and intensity will be necessary in the future if the full effects of these sounds are to be assessed.
Characterization of nano-electro-mechanical systems (NEMS) using photoacoustic microscopy
Authors: SampathKumar A. , Ekinci K. L. , Murray T. W.
Published: October 2013

A photoacoustic microscopy system has been developed for the noncontact characterization of materials at the micro- and nanometer scale. The system uses an electroabsoption modulated laser source for material excitation and a path-stabilized interferometer to detect the resulting displacements. Using this system, we describe the optical excitation and detection of high-frequency nanoelectromechanical systems (NEMS) at am-bient temperature and pressure. Using a tightly focused modulated laser source, we have actuated the out-of-plane flexural resonances of bi-layered doubly clamped nanomechanical beams. The optically detected displacement profiles in these beams are consistent with a model where the absorbed laser power results in a local temperature rise and a subsequent thermally induced bending moment. The excitation technique allows probing and actuation of NEMS with excellent spatial and temporal resolution. From a device perspective, the technique offers immense frequency tunability and may enable future NEMS that can be remotely accessed thus obviating the need for electronic coupling. [The authors gratefully acknowledge funding from National Science Foundation under Grants ECS-0304446 and ECS-0210752.]
Development of 1-3 piezocomposites for U. S. Navy applications
Authors: Howarth Thomas R. , Benjamin Kim C.
Published: October 2013

Efforts to develop 1-3 piezocomposite materials for U.S. Navy applications began in the early 1990s at the former Naval Research Laboratory’s Underwater Sound Reference Detachment in Orlando, FL. These initial investigations concentrated on evaluating the materials properties and parameters from a number of different contractors and manufacturing techniques. This was followed by efforts to initially fabricate receiving devices to replace traditional piezoceramic sensor prototypes, followed by development of devices with both receiving and transmitting capabilities. The presentation will discuss the initial NRL-USRD efforts and follow the development of 1-3 piezocomposite materials from these humble beginnings to devices that are currently being used and further developed by the U.S. Navy. [Work supported by the NRL, ONR, DARPA, and NAVSEA.]
Use of complex source points to simplify numerical Gaussian beam synthesis
Authors: Forsythe Stephen
Published: October 2013

It is often desirable to generate the acoustic field due to a so-called Gaussian beam. One way to do this is to use the free-space Green’s function for the acoustic field and to sum small area sources over a circular plate with the appropriate shading for the desired Gaussian beam. For very high frequencies and narrow beams, the computation time to give an accurate sum can be large when calculating the sum for many points in the acoustic field. An alternate approach comes from the use of a single point source with complex coordinates R=(Xr+i*Xi,Yr+i*Yi,Zr+i*Zi). When this complex source point is used in the free-space Green’s function, the formal expressions for pressure and particle velocity can be used if careful attention is paid to the interpretation of the complex distance, r, that arises in the exp(ikr)/r term. The singularity is no longer a single point in the case of a complex source, but a circular disk. The far field of a complex source point is a good approximation to a Gaussian beam. Several computational uses of the technique will be demonstrated. Extension to the shear wave Green’s function will be explored. [Work supported by ONR.]
Rationale for a new loudness standard
Authors: Hellman Rhona P.
Published: October 2013

In 2005, a new loudness standard was approved by ANSI for calculating the loudness of steady sounds. The new standard is based on a recent loudness model [Moore et al., J. Audio Eng. Soc. 45, 224–240 (1997)] derived from an earlier model devised by Zwicker [Acustica 8, 237–258 (1958)]. It replaces and supersedes the more limited computational procedure used in the old ANSI S3.4-1980 standard that had its origins in the protocol developed by S.S. Stevens [J. Acoust. Soc. Am. 33, 1577–1585 (1961)]. Unlike the old ANSI S3.4-1980 procedure, the newly adopted ANSI standard can be applied to sounds with sharp line spectral components as well as to broadband spectra. The new standard also extends the dynamic range for loudness calculations to loudness levels below 40 phons. Hence, it can be used to estimate loudness, or loudness level, with reasonable accuracy at levels close to threshold. Moreover, in accord with the revision of ISO 226 [International Organization for Standardization, Geneva (2003)], it enables the loudness of complex sounds containing spectral energy below 500 Hz to be determined. Empirical examples that illustrate the broader and more accurate scope of the new loudness standard are presented.
The Cambridge loudness model: Design principles and predictions
Authors: Moore Brian C. J. , Glasberg Brian R. , Baer Tom
Published: October 2013

The Cambridge loudness model, which forms the basis for the new ANSI standard (ANSI S3.4-2005), is similar in structure to loudness models proposed earlier by Fletcher and by Zwicker, but differs in many of the details. The input signal to each ear is specified in terms of its spectrum, which may be defined in 1/3-octave bands, or as the sum of a series of sinusoidal components and one or more pink-or white-noise bands. The first stage of the model is a filter to account for the transfer of sound from the sound field or headphone to the eardrum. The second stage is a filter to account for the transfer of sound through the middle ear. The third stage transforms the effective spectrum reaching the cochlea to an excitation pattern, calculated as the output of an array of level-dependent auditory filters. In the final stage, the excitation at each center frequency is converted to specific loudness, by a nonlinear frequency-dependent transformation. The specific loudness is summed across frequency to give the loudness for each ear, and is summed across ears to give overall loudness. The model accounts well for the effects of level, frequency, and bandwidth on loudness.
The new International Organization for Standardization (ISO) standard for the equal-loudness contours: Comparison to earlier contours and procedures
Authors: Suzuki Yôiti , Takeshima Hisashi
Published: October 2013

Equal-loudness contours exhibit the intensity-frequency characteristic of the auditory system. Since 1956 such contours based on the free-field measurements of Robinson and Dadson [Br. J. Appl. Phys. 7, 166–181 (1956)] have been widely accepted as an international standard in ISO 226. However, in 1985 some questions about the general applicability of these standard contours were raised to ISO TC/43 WG1 by Fastl and Zwicker. Consequently, a new international effort to measure the equal-loudness contours was undertaken. In 2003, this effort produced a revision of ISO 226. The newer experimental data and their analyses were subsequently published by Suzuki and Takeshima, [J. Acoust. Soc. Am. 116, 918–933 (2004)]. The revised contours more closely agree with the classic contours measured by Fletcher and Munson [J. Acoust. Soc. Am. 5, 82–108 (1933)] than with those produced by Robinson and Dadson. This finding is especially true below 500 Hz at moderate loudness levels. Moreover, the revised contours are in good overall agreement with the contours calculated according to the procedure proposed by Moore et al. [J. Audio Eng. Soc. 45, 224–240 (1997)]. In 2005, this procedure was adopted by ANSI for loudness calculations of steady sounds to replace ANSI S3.4-1980. Comparative examples are given.
Assessment of incipient material damage and remaining life prediction with nonlinear acoustics
Authors: Donskoy Dimitri , Zagrai Andrei , Chudnovsky Alexander , Golovin Edward , Agarwala Vinod S.
Published: October 2013

Subjected to a wide spectrum of operational and environmental loads, engineering structures exhibit first signs of material deterioration at micro and meso scales. In contrast to nondestructive assessment of the macro-scale damage that resulted from material fracture, a limited number of technologies have tackled the complex task of detecting and monitoring the small-scale incipient damage. This paper discuses application of the nonlinear acoustic vibro-modulation technique for assessment of the micro/meso scale fatigue damage and remaining life prediction of metallic samples. A nonlinear acoustic damage index (DI), which indicates strength of the damage-induced nonlinear interaction of the high-frequency ultrasonic wave and the low-frequency structural vibration, was monitored during a set of strain-controlled fatigue tests. Stable growth of the damage index was observed at an increasing number of fatigue cycles showing correlation between DI and the micro/meso scale damage accumulation. This correlation allowed for introducing DI in the remaining life prediction methodology based on an entropy density criterion of local failure. Experimental testing confirmed the effectiveness of the proposed prediction approach. [Work supported by NAVAIR.]
Space-dependent damping for reducing vibration of continuous systems
Authors: Holdhusen Mark H.
Published: October 2013

Structural vibration in continuous systems is a common source of problems for many mechanical systems. Much research has considered ways to reduce the vibration in continuous systems. Some research uses passive techniques that are simple to implement, whereas other methods implement active control that can be quite complex. The research presented here investigates the effect space-dependent damping has on the vibration of continuous systems. Specifically, the work at hand will focus on the flexural vibration of beams. In a distributed damping beam system, the damping is variable as a function of position along the length of the beam. Such a system could be physically realized through the use of magneto-rheological or electro-rheological fluids. Along its length, a beam could be divided into several isolated sections containing such a fluid. By controlling the magnetic or electric field across each section of the beam, the damping would vary along the length of the beam. The work presented here optimizes the damping as a function of beam position to reduce the broadband frequency response of the beam. A number of support conditions for the vibrating beam are considered.
Modeling the influence of acoustic loading on laryngeal self-sustained oscillations
Authors: Zañartu Matías , Mongeau Luc , Wodicka George R.
Published: October 2013

Three-way interactions between sound waves in the subglottal and supraglottal tracts, the vibrations of the vocal folds, and laryngeal flow were investigated. Nonlinear coupling was investigated analytically, with a focus on the effects of a realistic acoustic loading on the self-sustained oscillation of the vocal folds. MRI-based shapes for the supraglottal tract [Story et al., J. Acoust. Soc. Am. 100, 537–554 (1996)] and an equivalent acoustical model for the subglottal tract [Harper et al., IEEE Trans. Biomed. Eng. 48, 543–550 (2001)] were considered. The model was based on the wave reflection analog technique, along with a novel single degree of freedom model of the vocal folds to describe the source. The effects of a mucosal wave on the vocal folds were incorporated through a time-varying discharge coefficient and a Bernoulli-type flow model. The relative importance of acoustic loading and time-varying flow resistance for fluid-structure energy transfer was compared for various configurations. [Work supported by NIH Grant RO1-DC05788.]
Gradient alternations and gradient attraction
Authors: Crosswhite Katherine
Published: October 2013

Many phonological alternations have been shown to be sensitive to lexical ‘‘gradient attraction,’’ defined by Burzio [‘‘Surface-to-surface morphology: When your representations turn into constrainsts,’’ Rutgers Optimality Archive ♯341-0999 (http://roa.rutgers.edu) (1998)] as follows: (A) The overall structure of a word W (in both phonological and semantic components) is influenced by that of other words in the lexicon to which W is independently similar, and which are thought of as ‘‘attractors’’ of W. (B) Attraction is stronger where independent similarity is greater. Since most strong attractors will be morphologically related to W, this results in a limitation on phonological alternations that would produce allomorphy. So far, gradient attraction has been studied for categorical alternations, such as stress placement in English (cf. compArable versus cOmparable). However, many alternations previously believed to be categorical are in fact gradient [as reviewed in, e.g., Port and Leary, ‘‘Against formal phonology,’’ Language 81, 927–964 (2005)]. This study documents the influence of lexical attraction on two gradient phenomena of English: polysyllabic shortening and flapping. Attractor strength was varied in two manners. First, each base used in the study was paired with both derivational and inflectional derivatives (i.e., rose-roses-rosy for polysyllabic shortening, and wait-waiting-waiter for flapping), and second by analyzing the effect of between-item variation in semantic relatedness for the derivationally related forms (cf. ice-icy versus nose-nosy).
Resonance tuning in soprano singing and vocal tract shaping: Comparison of sung and spoken vowels
Authors: Narayanan Shrikanth , Bresch Erik , Tobin Stephen , Byrd Dani , Nayak Krishna , Nielsen Jon
Published: October 2013

Singing at high pitches by sopranos involves complex orchestration of vocal-fold mechanisms and vocal-tract shaping. A specific phenomenon is the tuning of vocal-tract resonances to the fundamental at high pitches. Measurement of vocal-tract resonances has shown that this is particularly true for the first resonance [Joliveau et al. (2004)]. Higher resonances show some increase in their values perhaps reflecting incidental effects rather than active tuning. We investigate vocal-tract shaping in soprano singing using a real-time MRI technique [Narayanan et al. (2004)] with synchronized noise-cancelled audio recording. A professionally trained Western-classical singer spoke and sang the vowels /a, i, u, o, e/ preceded by the consonant /l/ over an ascending scale (from B-flat below middle C, rising two octaves). Acoustic analysis shows clear evidence of F1 tuning to F0 in the higher-octave singing of the vowels. The vocal-tract shape was distinctly different at the higher pitches compared to vowels spoken at normal pitch and those sung at the lower octave, with fairly large oral and pharyngeal cavities, created by a highly bunched and retracted tongue, and a raised larynx. At the highest pitch, the vocal-tract shape differences between the vowels are considerably lessened, although some vestigial canonical tongue shapes appear to remain. [Work supported by NIH, USC Annenberg Center.]
Short-term non-poissonian temporal clustering of magnitude 4+ earthquakes in california and western nevada
Authors: Ebel John E. , Chambers Daniel W. , Kafka Alan L. , Baglivo Jenny A.
Published: October 2013

The M4+ mainshocks throughout California and western Nevada from 1932 to 2004 show non-Poissonian temporal clustering over time periods of a few days. The short-term clustering is independent of the distance between earthquake epicenters. It implies that some of the M4+ mainshocks are mutually triggered by some unknown regional cause. In southern California, more short-term clustering is found for M4+ earthquakes east of the San Andreas Fault. In central California, most M4+ mainshocks at Long Valley, CA have occurred within 10 days of M4+ mainshocks around the San Francisco Bay area. The clustering implies predictable behavior in the occurrences of M4+ mainshocks. We propose a hidden Markov model (HMM) as an earthquake forecast method for the region. Our HMM assumes a hidden sequence of interevent time states associated with observations of earthquake occurrences (times, locations, and magnitudes) with transition probabilities between states determined with the Baum-Welch algorithm and the past earthquake data. Given the seismic history up to the latest earthquake, the probability of another earthquake within the next few days is estimated. Tests of our HMM with two, three, and four temporal states show some modest success. We plan to extend the model to forecast magnitude and spatial parameters.
Modeling of glints due to surface curvature using the virtual source technique
Authors: Abawi Ahmad T. , Porter Michael B. , Siderius Martin
Published: October 2013

The virtual source technique, also known as the method of superposition or the auxiliary source technique, has been widely used to model scattering from targets. In this technique the target is replaced by a collection of sources of unknown complex amplitudes. The source amplitudes are calculated by applying the appropriate boundary conditions at the surface of the target. In this paper, the virtual source technique is used to compute scattering from rough surfaces. For sound scattering from the rough ocean surface, this is done by solving the wave equation for a half-space ocean overlaying a bottom and forcing the solution to satisfy the pressure-release boundary condition at a desired surface. The method is applied to study the effect of focusing of energy (glints) due to reflection of sound from a gently sloping, but concave ocean surface for various ocean conditions. Additionally, the method is applied to the study of scattering of waves from an infinite periodic surface.
High-frequency limit under the Rayleigh hypothesis
Authors: Elfouhaily Tanos , Hahn Thomas
Published: October 2013

The Rayleigh hypothesis (RH) is traditionally invoked to compute the scattering amplitude in rough surface scattering. This hypothesis simplifies the analytic derivation of the scattering problem and has been proven to be accurate for the determination of the Volterra series for the small perturbation method (SPM). The SPM development physically corresponds to the scattering of low-frequency acoustical waves. In this study we focus on the high-frequency limit under the Rayleigh hypothesis (RH). We validate the consistency of the RH with the high-frequency limit to the order invoked in the approximation. This means that the first-order geometrical optics (GO1) is reached even though the Rayleigh hypothesis consists of the summation of solely upward scattered fields.
‘‘Passing Landscapes.’’
Authors: Moses James
Published: October 2013

This 15-min piece is composed from five-channel surround sound environmental and naturalistic concert hall recordings of original music. Cross-synthesis and resonant filtering techniques are used to create harmonic and melodic content from the environmental recordings. The synthesized components move in the surround soundfield against the stable spatial image of the source recordings. The environmental recordings include bucolic settings, a downtown cityscape, a highway traffic scene, a public gathering, and a composed ambience/montage of sounds from our electronic media culture. The various environmental recordings are juxtaposed with each other and with concert hall material to create the form of the piece. The piece intends to provide a contextualized view of aspects of modern life and technology.
Strategies for bat echolocation estimated through characteristics of pulse and echo measured by a telemetry microphone
Authors: Riquimaroux Hiroshi
Published: October 2013

How echolocating bats extract important information from multiple targets during flight was investigated by a small and very light telemetry microphone system (Telemike) mounted on the head. A high-speed video camera system was also adopted together with Telemike to trace positions in space of the flying bat for analyzing spatio-temporal pulse emission patterns and flying velocity. With those devices, how the bats executed parallel time-sharing real-time processing during their flight could be examined. Taiwanese leaf-nosed bats (H̑ipposideros terasensis), CF-FM bats, were used as subjects. The Doppler-shift compensation was confirmed during flight where the frequency of the dominant second harmonic of constant frequency component, CF2, of returning echoes was kept constant by adjusting CF2 frequency of emitting pulses. Estimated frequencies of CF2 of pulses from the bats flight speed strongly agreed with actually observed values. Pulse frequencies were also estimated using echoes returning directly ahead of the bat and from its sides for two different flight conditions: landing and U-turning. Temporal patterns for Doppler-shift compensation, interpulse interval, and echo delay showed that bats in flight alternately changed their attended direction from one to another. Bats were also observed to change the intensity and emission rate of pulses depending on the distance from the landing site. [Work partly supported by the Innovative Cluster Creation Project promoted by MEXT and by a grant to RCAST at Doshisha University from MEXT.]
Cepstral processing for bat biosonar
Authors: Buck John R. , Simmons James A. , DeLong Caroline M.
Published: October 2013

Bats routinely discriminate multiple glint targets whose interglint time spacings are much less than the integration time of the bat auditory system. This suggests that the bats are exploiting spectral cues in the received echos to resolve the glints. Closely spaced glints cause notches and peaks in the received signal spectrum with frequency spacings characteristic of the glint separations. A biologically inspired signal processing algorithm for resolving these echos into target images is described. The algorithm combines a coarse energy detector to locate targets with a windowed short-time cepstral analysis, or cepstrogram, to resolve the fine structure of the detected targets. The algorithm’s performance is demonstrated using data recorded in a laboratory experiment. The experiments transmit an ultrasonic chirp and record the echos from a target consisting of a pair of cylinders spaced 5 cm apart, presented at aspect angles ranging from 0 to 90 deg. These recordings are processed with the cepstrogram algorithm using parameter choices commensurate with the performance of the bat auditory system. The cepstrogram algorithm accurately estimates the spacing of the cylinders. Combining the results from the left and right receiver channels produces a binaural image of the target. [Work supported by ONR.]
Evaluation of performance of the echolocation model for the restoration of an acoustic image from a single-emission echo
Authors: Matsuo Ikuo , Magara Takashi , Yano Masafumi
Published: October 2013

Using frequency-modulated echolocation sound, bats can form a fine acoustic image of an object. The acoustic image is an impulse response, known as a reflected-intensity distribution, which is composed of amplitude and phase spectra over a range of frequencies. However, bats detect only the amplitude spectrum due to the low-time resolution of their peripheral auditory system, and the frequency range of emission is restricted. The amplitude spectrum varies with the changes in the configuration of the reflected-intensity distribution, while the phase spectrum varies with the changes in its configuration and location. By introducing some reasonable constraints, we previously proposed a method for restoring an acoustic image from the echo produced by a single emission. The configuration is extrapolated from the amplitude spectrum of the restricted frequency range by using the continuity condition of the amplitude spectrum at the minimum frequency of the emission and the minimum phase condition. The location is estimated from the temporal changes of the amplitude spectra computed by the convolution of the Gaussian chirplet with a carrier frequency compatible with bat emission sweep rates. In this paper, the performance of this model is evaluated by measuring and analyzing the echo reflected from the object.
A single-channel low-frequency method for ultrasound imaging
Authors: White P. J. , Clement G. T.
Published: October 2013

Transcranial ultrasound imaging of brain structures and pathologies have traditionally suffered from compromised signal-to-noise ratios due to the bone-mediated increase in signal attenuation with increasing frequency. Yet, established modalities of image reconstruction with ultrasound measurements rely on higher frequencies for radial resolution and large temporal bandwidths for axial resolution. A new method that substantially reduces the dependency of image resolution on ultrasound frequency is proposed. Using an asymmetric transducer design, an unfocused, broadband, and frequency-separated ultrasound field is created in a region-of-interest (ROI). In this fashion, a unique complex spectral label can be assigned to each point in the ROI with a spatial resolution independent of source frequency. Ultrasound scattering sites within the ROI are then spatially localized by identifying the unique frequency-phase signature detected by either a point receiver or by the transmitting transducer. A cross-correlation method is used to reconstruct the echogenic profile of the ROI using a priori measurements of the field. Since the method’s axial and radial resolutions are dependent on bandwidth rather than frequency, deeper penetration into tissues and application in highly attenuation tissues is feasible. Also, the prospect of multiple-dimension imaging with a single channel will allow for reduced emitter and electronic complexity. [Work supported by NIH: R21EB004353 and U41RR019703.]
Contact problems with friction applied to musical sound synthesis
Authors: Bensoam Joel
Published: October 2013

Modalys, a sound synthesis software developed at Ircam for research and musical applications, allows one to build virtual instruments based on physical models to obtain the most entire range of expressive variations in the instrument in response to intuitive controls. An instrument, as a complex structure, is described by the mechanical/acoustical interaction of its components (strings, tubes, resonators, soundboard,...). Some new research has been done recently to extend the sound prediction to three-dimensional objects with the help of numerical methods. In particular, theoretical and numerical treatment of the unilateral dynamic contact with friction between two arbitrary elastic bodies is studied. In addition to the classical variational statement that arises from static problems, a dynamic contact condition is needed and found by adjusting the energy balance law to the impenetrability condition. In the context of infinitesimal deformation, a reciprocal formulation is then used to reduce this well-posed problem to one involving Green functions defined only on contact surfaces. This allows us to use considerably fewer unknowns compared to finite difference algorithms. The ability of the method to predict the contact interaction between two elastic bodies, irrespective of the material constitution and geometry, is highlighted by analytical and numerical simulations.
Tuning parameters of a Nigerian slit gong
Authors: Skubal Jacob , Hall Nathan , Moore Thomas
Published: October 2013

The Nigerian slit gong is a wooden idiophone, hand-carved from a single log, that is characterized by its ability to produce two distinct notes when struck. The resonant modes of the gong have been studied using a finite-element analysis model, which was validated by comparing the predicted mode shapes to those observed by electronic speckle pattern interferometry. Using this model, the effects of changing the parameters available to the artisan when carving the instrument have been studied. Results of the model are compared with a simple theory, and the physics of tuning the Nigerian slit gong is discussed.
Turbulent finite difference model of simplified musical geometries
Authors: Linke David , Janssen Berit
Published: October 2013

A turbulent flow in a two-dimensional space is modeled using a finite difference method of the Navier-Stokes equation taking the k-epsilon turbulence model into account. In this formulation the flow is divided into a laminar and an averaged turbulent part. Mathematically this changes the normal Navier-Stokes equation into the Reynolds averaged Navier-Stokes equation. Kolmogorov’s idea was that the energy of the laminar flow is transverted into eddies which get smaller down to the smallest eddy size, where this enery is completely dissipated. This introduces two new parameters, the turbulent energy k and the turbulent dissipation epsilon. Generally this turbulence model adds additional damping through the Reynolds stress tensor. This investigation compares turbulent and nonturbulent flows using different musical relevant geometries, like surfaces and edges.
Characterization of elasticity, friction, anelasticity, and adhesion with nm lateral resolution, using the ultrasonic vibration modes of atomic force microscope cantilevers
Authors: Arnold W. , Caron A. , Rupp D. , Schwarz K. , Hirsekorn H. , Rabe U.
Published: October 2013

Ultrasound is combined with atomic force microscopy to achieve the lateral resolution of scanning probes for imaging. Atomic force acoustic microscopy (AFAM) and ultrasonic friction force microscopy (UFFM) exploit the vibrational modes of AFM cantilevers which extend from 10 kHz to several MHz. In the AFAM mode the cantilever vibrates in contact mode in one of its flexural resonances. Images can be obtained with the contrast depending on the local indentation modulus, which can be obtained quantitatively from the contact resonance frequencies. The lateral resolution is defined by the tip-sample contact radius and is 10 nm. At large ultrasonic amplitudes nonlinear effects that are related to adhesion become important. In UFFM shear stiffness and friction phenomena can be examined by evaluating the torsional cantilever resonances. At low lateral surface amplitudes, the sensor tip remains in elastic contact and the cantilever behaves like a linear torsional oscillator with damping. If the amplitude exceeds a critical value, the resonance develops a plateau due to stip-slick in the tip-sample contact, allowing one to monitor friction. Ultrasonic C-scan images and the corresponding contact resonance spectra will be shown and compared to theory. Applications of the AFAM techniques to measure local piezoelectricity and anelasticity will be discussed as well.
High-resolution ultrasound: A survey
Authors: Tittmann Bernhard R.
Published: October 2013

This presentation provides a survey of high-resolution ultrasonic techniques and examples. With the discovery by Baranski, followed by the work of Boemmel and Dransfeld, the field of hypersonic wave propagation began to come into its own. The measurements over a range of frequencies from 100 MHz to 2 GHz, first in superconducting lead and then in type-II superconductors by Tittmann, took place under cryogenic temperatures. These and other results provided impetus for the development of a room temperature scanning acoustic microscope (SAM) by Quate. The licensing to three organizations for manufacturing the SAM led to the sale of many instruments which have since been used by many researchers around the world for materials characterization. This work was enhanced by Weglein with the interpretation of the V(z) signature of materials. The room temperature SAM requires fluid for ultrasonic coupling and provides about 1 micron resolution at 1 GHz. With the onset of nanotechnology even finer resolution was required and the atomic force microscope was adapted by several groups around the world for use with ultrasound with the development of U-AFM and AFAM. This presentation will provide several examples of methods and results throughout the development of high-resolution measurement capability.
Two types of learning revealed by evaluation of the best and worst daily performance during auditory-discrimination training
Authors: Wright Beverly A. , Zhang Yuxuan , Stewart Christopher C.
Published: October 2013

Performance on many auditory discrimination tasks improves with practice. This learning could result from improvements in fundamental processing capacity (as is implicitly assumed), from improvements in the ability to consistently access already existing capacities, or from a combination of the two. To help distinguish among these types of improvement, we reanalyzed learning data on three basic auditory tasks, examining the best and worst, rather than the mean, thresholds on each of 6–10 days of training. On one task (interaural-level discrimination), the best and worst thresholds decreased in parallel, indicating an improvement in fundamental processing capacity. On another task (interaural-time discrimination), the best thresholds remained unchanged but the worst thresholds decreased, suggesting an increased consistency in accessing already existing capacities. Demonstrating a combination of these two types of improvement, on the third task (duration discrimination), both the best and worst thresholds improved, but the worst thresholds improved more. These results indicate that learning on auditory tasks can result not only from refinements in fundamental stimulus encoding, but also from increases in the ability to use the best information that was already available before training. [Work supported by NIH/NIDCD.]