bluuebunny/crossref_metadata_2025 huggingface dataset:
Supersonic naval missile sounds over San Nicolas Island
Authors: Greene Charles R. , Norman Robert G. , Holst Meike , Malme Charles I.
Published: October 2013

Vandals and other missiles are launched occasionally from San Nicolas Island, CA, during Naval exercises and tests. Pinnipeds on the island beaches are exposed to the flight sounds, some of which are sonic booms from directly overhead. Environmental concerns led the Navy to support acoustic studies of the missile sounds at the beaches. The results show flat-weighted sound pressures from Vandals as high as 150 dB re: 20 μPa(peak) [140 dB re: 20 μPa(rms)] at a near-vertical distance of 400 m. Other flat-weighted pressures from Vandals were as low as 107 dB re: 20 μPa(peak) [95 dB re: 20 μPa(rms)] at a beach 3.9 km horizontally behind the launcher. Pulse durations and sound exposure levels were also measured. One-third octave band sound exposure levels were measured. All parameters (except one-third octave band levels) were also measured with A weighting. Other missiles measured include Tomahawk cruise missiles, Rolling Airframe Missile, Advanced Gun System, Terrier, and the Supersonic Sea-Skimming Target. [Work supported by U.S. Navy.]
Acoustical enhancement systems: Design criteria and evaluation of room acoustical parameters based on in situ measurements
Authors: van Munster Bjorn , Prinssen Wim
Published: October 2013

Acoustic enhancement systems have evolved significantly during the years. Where the early systems only aimed to increase the reverberation time in a hall, nowadays the increase of the reverberation time is only one of the features of such a system. Contrary and additionally to passive acoustics, an acoustic enhancement system enables a designer or acoustical consultant to change the acoustical characteristics of a hall in a more flexible way. Due to the sophisticated convolution processes and layout of such a system besides the reverberation time also, e.g., speech intelligibility and spaciousness can be improved or special effects can be added to shows. In this paper the applications of an enhancement system in general will be outlined in more detail. Furthermore, design criteria will be given which can be formulated for the installation of such a system. These criteria can be used to evaluate proposed designs, but also to estimate the required provisions to be included in the planning of a system installation. Besides, the paper describes the results of in situ measurements of one such system (SIAP) whereby the increase of the reverberation time is evaluated with respect to certain important room acoustical parameters, i.e., reverberant level, lateral efficiency and clarity.
Investgation of sediment properties with a rotated coordinates inversion technique
Authors: Neilsen Tracianne , Isakson Marcia , Worley Andrew
Published: October 2013

Several models have been developed that describe the interaction of high-frequency sound with ocean sediments. This work presents how estimates of the seabed properties can be obtained with a simulated annealing inversion algorithm that minimizes the difference between measured and modeled reflection loss within the statistical nature of the data and the statistical nature of the parameters. Because there is often a correlation between how the various seabed properties influence the reflection loss of acoustic waves, the efficiency and accuracy of the inversion can be improved by using a rotated set of coordinates to navigate the search space in the inversion. The rotated coordinates are obtained by performing an eigenvalue decomposition of the covariance matrix of the gradients of the cost function. The resulting eigenvectors are the rotated coordinates, show the couplings between the seabed parameters, and are used to vary the parameters in the inversion. The corresponding eigenvalues indicate the relative sensitivities of the cost function to changes in the parameters and provide insights into how the inversion problem can be effectively decoupled [T. B. Neilsen, ‘‘An iterative implementation of rotated coordinates for inverse problems,’’ J. Acoust. Soc. Am. 113, 2574–2586 (2003)]. [Work supported by ONR.]
Separating thermal coagulation and cavitation effects in HIFU attenuation measurements
Authors: Reed Justin , Bailey Michael , Anand Ajay , Kaczkowski Peter
Published: October 2013

HIFU can be used to destroy tumors. The conversion of acoustic energy into heat causes protein coagulation (Lesion) in tissue. Attenuation measurements have been proposed to monitor the progression of thermal therapy. The goal of this work is to study and separate the effects of cavitation and thermal coagulation in attenuation measurements. A HIFU transducer was used to treat Bovine liver. A receiving transducer mounted across from the transmitting HIFU transducer measured attenuation during the treatment. A pressure chamber provided static pressure greater than the pressure amplitude of the HIFU wave, which suppressed cavitation. rf data from a commercial ultrasound scanner was also obtained. A large increase in attenuation was observed with cavitation present, while a subtle increase in attenuation was observed with cavitation suppressed. Attenuation estimated from the RF data showed an increase in attenuation downstream of the location of the lesion with cavitation present, while a subtle increase in attenuation was observed at the location of the lesion with cavitation suppressed. It has been found that attenuation measurements are greatly affected by the presence of cavitation, and the actual effect of thermal coagulation on attenuation is quite small. [Work supported by NIH, NSF, NSBRI.]
Numerical investigation of dual-frequency HIFU pulsing for lithotripsy
Authors: Kreider Wayne , Bailey Michael , Crum Lawrence
Published: October 2013

As an alternative to traditional shock-wave lithotripsy, high-intensity focused ultrasound (HIFU) is currently being investigated for its capability to comminute renal calculi. Because current data indicate that cavitation plays a role in both stone comminution as well as collateral tissue damage, the cavitation effects of HIFU treatment strategies are investigated numerically. In particular, numerical simulations are designed to model the response of bubbles to acoustic excitations generated by a prototype, dual-frequency HIFU transducer for lithotripsy. The prototype transducer is capable of producing both high- (∼4-MHz) and low-frequency (∼100-kHz) outputs, while the bubble dynamics are modeled by the Gilmore equation for a single spherical bubble subject to diffusion. Numerical simulations are currently ongoing to investigate the effects of the relative phase between high and low-frequency pulses. Initial results demonstrate that the simultaneous application of high and low-frequency pulses can generate maximum pressures several orders of magnitude higher than high-frequency pulses alone.
Sound quality evaluation of air conditioning sound rating metric
Authors: Hodgdon Kathleen K. , Peters Jonathan A. , Burkhardt Russell C. , Atchley Anthony A. , Blood Ingrid M.
Published: October 2013

A product’s success can depend on its acoustic signature as much as on the product’s performance. The consumer’s perception can strongly influence their satisfaction with and confidence in the product. A metric that can rate the content of the spectrum, and predict its consumer preference, is a valuable tool for manufacturers. The current method of assessing acoustic signatures from residential air conditioning units is defined in the Air Conditioning and Refrigeration Institute (ARI 270) 1995 Standard for Sound Rating of Outdoor Unitary Equipment. The ARI 270 metric, and modified versions of that metric, were implemented in software with the flexibility to modify the features applied. Numerous product signatures were analyzed to generate a set of synthesized spectra that targeted spectral configurations that challenged the metric’s abilities. A subjective jury evaluation was conducted to establish the consumer preference for those spectra. Statistical correlations were conducted to assess the degree of relationship between the subjective preferences and the various metric calculations. Recommendations were made for modifications to improve the current metric’s ability to predict subjective preference. [Research supported by the Air Conditioning and Refrigeration Institute.]
Model building codes and acoustical performance: Where are we in 2003?
Authors: Tinianov Brandon
Published: October 2013

The proper acoustical design for multi-family dwellings is an important factor in occupant comfort. Key acoustical design practices are often not mandated by the builder or architect, but by the applicable building codes. In early 2003, the three regional/national building codes agreed to join into a single, unified national building code for residential and commercial construction. The scope and governance of these three codes: the Uniform Building Code (ICBO), the National Building Code (BOCA), the Southern Building Code (SBCCI) are reflected in the International Residential Code (IRC) and the International Building Code (IBC) which was developed by the International Code Council (ICC). With the move to a single code body, those concerned with building acoustical performance welcome the benefit of a single minimum standard. Unfortunately, this new minimum performance requirement does not reflect the state of the science for occupant satisfaction. The acoustical requirements of each of these building codes, the timeline of their development and an overview of the state of the science will be presented. Suggestions for revised performance minimums will also be offered for discussion.
Radiation force on a compressible cylinder in a standing wave: Long-wavelength approximation
Authors: Wei Wei , Thiessen David B. , Marston Philip L.
Published: October 2013

For situations where compressible cylinders are manipulated using acoustic standing waves, it is desirable to have a simple long wavelength approximation of the radiation force analogous to the sphere result published by Yosioka and Kawasima in 1955. That result has also been derived from the Rayleigh scattering approximation of the monopole and dipole scattering contributions. The analogous result for a rigid-movable cylinder (that may have a different density than the surroundings) was given by the first line of Eq. (24) of Wu et al. [J. Wu, G. Du, S. S. Work, and D. M. Warshaw, J. Acoust. Soc. Am. 87, 581–586 (1990)]. The cylinders axis is parallel to the standing wave nodal planes. To generalize that result to a compressible cylinder it is only necessary to replace a monopole term [the final unity term in the curly brackets in the first line of Eq. (24)] by (l−R) where R denotes the ratio of the adiabatic compressibility of the inner fluid to that of the outer fluid. This modification agrees with the form of the monopole scattering contribution for cylinders in the Rayleigh approximation and recovers numerically the low frequency limit for the radiation force-per-length based on the full partial-wave series. [Work supported by NASA.]
Apparent integrated backscatter from cancellous bone in the frequency range 2.5–7.5 MHz
Authors: Hoffmeister Brent K. , Jones Charles I. , Kaste Sue C.
Published: October 2013

Ultrasonic backscatter may offer useful new techniques for ultrasonic bone assessment. For this study, backscatter measurements were performed on 18 specimens of bovine cancellous bone using a 5-MHz broadband ultrasonic system operating between 2.5–7.5 MHz. Specimens were obtained from the proximal tibia, and prepared in the shape of cubes (15-mm side length) with faces oriented along principal anatomic directions (anterior, posterior, medial, lateral, superior, and inferior). A mechanical scanning system was used to acquire ultrasonic backscatter signals from 144 sites perpendicular to each face of each cube. The signals were analyzed to extract values of apparent integrated backscatter (AIB), a parameter that represents the frequency-averaged backscattered power uncompensated for the effects of attenuation and diffraction. AIB demonstrated highly significant linear correlations with bone mineral density (BMD) for both the transverse (anterior, posterior, medial, and lateral) and longitudinal (superior and inferior) directions. In all cases AIB decreased with increasing BMD. No significant anisotropy was detected. We conclude that AIB measurements performed on bovine cancellous bone in this range of frequencies correlate well with BMD.
Simulated axial transmission propagation on cortical bone
Authors: Talmant M. , Bossy E. , Laugier P.
Published: October 2013

The ultrasonic axial transmission technique, used to assess cortical shells of long bones, is investigated using numerical simulations. The 3-D finite difference code generates synthetic signals recorded at different distance emitter–receiver for a linear arrangement of transducers placed along the bone axis. Academic modeling of bone based on cylindrical tubular shape made of anisotropic and porous material has been reported [J. Acoust. Soc. Am. 115 (2004)]. The aim of this paper is to refine the model by taking into account more realistic structural and material bone properties. Finite difference modeling was applied to 50 human radius specimens which were examined both by x-ray tomography at different resolutions and by ultrasonic axial transmission technique (1 MHz). The x-ray macroscopic geometry (pixel around 100 μm) of the 50 samples was imported in the code. Material properties are assigned to each bone according to its own microarchitecture examined at a 10 μm scale. Different assumptions of the relationship between bone structural properties and material properties were tested. Simulations were validated by comparison with experimental results. Numerical simulations of transient propagation in bone is a powerful tool to enlighten interaction between ultrasound and bone and consequently to improve ultrasound based devices for clinical use.
Spoken name pronunciation evaluation
Authors: Tepperman Joseph , Narayanan Shrikanth
Published: October 2013

Recognition of spoken names is an important ASR task since many speech applications can be associated with it. However, the task is also among the most difficult ones due to the large number of names, their varying origins, and the multiple valid pronunciations of any given name, largely dependent upon the speaker’s mother tongue and familiarity with the name. In order to explore the speaker- and language-dependent pronunciation variability issues present in name pronunciation, a spoken name database was collected from 101 speakers with varying native languages. Each speaker was asked to pronounce 80 polysyllabic names, uniformly chosen from ten language origins. In preliminary experiments, various prosodic features were used to train Gaussian mixture models (GMMs) to identify misplaced syllabic emphasis within the name, at roughly 85% accuracy. Articulatory features (voicing, place, and manner of articulation) derived from MFCCs were also incorporated for that purpose. The combined prosodic and articulatory features were used to automatically grade the quality of name pronunciation. These scores can be used to provide meaningful feedback to foreign language learners. A detailed description of the name database and some preliminary results on the accuracy of detecting misplaced stress patterns will be reported.
Determining the threshold for usable speech within co-channel speech with the SPHINX automated speech recognition system
Authors: Hicks William T. , Yantorno Robert E.
Published: October 2013

Much research has been and is continuing to be done in the area of separating the original utterances of two speakers from co-channel speech. This is very important in the area of automated speech recognition (ASR), where the current state of technology is not nearly as accurate as human listeners when the speech is co-channel. It is desired to determine what types of speech (voiced, unvoiced, and silence) and at what target to interference ratio (TIR) two speakers can speak at the same time and not reduce speech intelligibility of the target speaker (referred to as usable speech). Knowing which segments of co-channel speech are usable in ASR can be used to improve the reconstruction of single speaker speech. Tests were performed using the SPHINX ASR software and the TIDIGITS database. It was found that interfering voiced speech with a TIR of 6 dB or greater (on a per frame basis) did not significantly reduce the intelligibility of the target speaker in co-channel speech. It was further found that interfering unvoiced speech with a TIR of 18 dB or greater (on a per frame basis) did not significantly reduce the intelligibility of the target speaker in co-channel speech.
Virtual acoustic reproduction of historical spaces for interactive music performance and recording
Authors: Martens William , Woszczyk Wieslaw
Published: October 2013

For the most authentic and successful musical result, a performer engaged in recording pianoforte pieces of Haydn needs to hear the instrument as it would have sounded in historically typical room reverberation, such as that of the original room’s in which Haydn taught his students to play pianoforte. After capturing the acoustic response of such historical room’s, as described in the companion presentation, there remains the problem of how best to reproduce the virtual acoustical response of the room as a performer moves relative to the instrument and the rooms boundaries. This can be done with a multichannel loudspeaker array enveloping the performer, interactively presenting simulated indirect sound to generate a sense of presence in the previously captured room. The resulting interaction between live musical instrument performance and the sound of the virtual room can be captured both binaurally for the performer’s subsequent evaluation, readjusted to provide the most desirable acoustic feedback to the performer, and finally remixed for distribution via conventional 5.1 channel audio media.
Acoustic mapping of squid egg clusters and their bottom habitat in Monterey Bay, California
Authors: Foote Kenneth G. , Hanlon Roger T. , Iampietro Pat J. , Kvitek Rikk G.
Published: October 2013

Clusters of gelatinous egg capsules, known as mops or beds, of the market squid (Loligo opalescens) were mapped in a shallow-water, sandy habitat of Monterey Bay, California. The benthic egg clusters were imaged using an EdgeTech 272-TD dual-frequency sidescan sonar towed from R/V MacGinitie, an 8-m-long survey vessel, with data recorded on a Triton Elics International Isis digital data acquisition system. Verification of target identity was accomplished independently by video photography from a remotely operated vehicle. The survey area included a 4-km stretch of sandy seafloor between Lover’s Point and Cannery Row in Monterey at depths of 15–30 m. The study area had previously been mapped using the RESON SeaBat 8101 240-kHz multibeam sonar. Resulting high-resolution bathymetric data, with 1-m resolution, were used during the survey planning and execution. Squid egg clusters were clearly visible in the very-high-resolution, 400-kHz backscatter imagery, with pixel size 10–20 cm, recorded from the towed sidescan sonar. The concentration of egg clusters was greatest along a sloping feature believed to be a submarine fault. Egg mops with diameter as small as 0.5 m were distinguishable. [Support by Sea Grant is acknowledged.]
Broadband acoustic backscatter and high-resolution morphology of fish: Measurement and modeling
Authors: Reeder D. Benjamin , Jech J. Michael , Stanton Timothy K.
Published: October 2013

Remote detection and classification of marine organisms require careful acoustic backscattering measurements and acoustic scattering models that adequately incorporate morphology. A study has been conducted on alewife (Alosa pseudoharengus), a swimbladder-bearing fish, which incorporated broadband (40–95 kHz) acoustic measurements, high-resolution imaging of fish morphology, and associated scattering modeling using the images. Live, adult alewife were insonified while being rotated in 1-deg increments of orientation angle in two planes of rotation (lateral and dorsal/ventral). These data provide orientation dependence of the scattering over a continuous band of frequencies, and identification of the dominant scattering features of the fish. X-ray and CT scan images of the swimbladder were digitized and incorporated into the Kirchhoff-Ray mode (KRM) model [Clay and Horne, J. Acoust. Soc. Am. 96, 1661–1668 (1994)] and the Fourier matching method (FMM), which has recently been extended to finite-length bodies of rotation [Reeder and Stanton, J. Acoust. Soc. Am. (2004), in press]. The CT scan imagery provides rapid, noninvasive, high-resolution morphological measurements in three dimensions. The potential of the new FMM formulation is demonstrated, which is a versatile approach, valid over a wide range of shapes, all frequencies and all angles of orientation. [Work supported by ONR and NOAA.]
Optimal volume backscattering thresholds for echo integration
Authors: Thomas Rebecca E. , Fleischer Guy W. , Ressler Patrick H.
Published: October 2013

Echo integration is a commonly used technique for assessment of fish stocks. In echo integration, a frequently used method to increase the signal-to-noise ratio is to ignore data below a set volume backscattering threshold. Although this form of thresholding is common, objective and replicable techniques for choosing this threshold are rarely used. Two opposing goals come into play when choosing an optimal threshold for estimating fish biomass using echo integration: maximizing the energy from backscatterers of interest, while simultaneously minimizing the energy from backscatterers not of interest. Both empirical and modeling techniques for choosing optimal thresholds were demonstrated using data from the 2003 integrated acoustic and trawl survey of Pacific hake. Empirical techniques were based on the receiver operating characteristic (ROC) curve. An ROC curve is a graphical plot of the number of true positives versus false positives for a binary classification system as the discrimination threshold is varied. Modeling techniques were based on volume backscattering data generated from modeled TS and density of hake and nonhake scatterers. For the case study using the 2003 Pacific hake survey, the historical threshold used for the southern portion of the survey was shown to be nonoptimal for that year.
50 years of progress in microphone arrays for speech processing
Authors: Elko Gary W. , Frisk George V.
Published: October 2013

In the early 1980s, Jim Flanagan had a dream of covering the walls of a room with microphones. He occasionally referred to this concept as acoustic wallpaper. Being a new graduate in the field of acoustics and signal processing, it was fortunate that Bell Labs was looking for someone to investigate this area of microphone arrays for telecommunication. The job interview was exciting, with all of the big names in speech signal processing and acoustics sitting in the audience, many of whom were the authors of books and articles that were seminal contributions to the fields of acoustics and signal processing. If there ever was an opportunity of a lifetime, this was it. Fortunately, some of the work had already begun, and Sessler and West had already laid the groundwork for directional electret microphones. This talk will describe some of the very early work done at Bell Labs on microphone arrays and reflect on some of the many systems, from large 400-element arrays, to small two-microphone arrays. These microphone array systems were built under Jim Flanagan’s leadership in an attempt to realize his vision of seamless hands-free speech communication between people and the communication of people with machines.
Noise control computer modeling for architectural academic education
Authors: Salameh Michael
Published: October 2013

Commercial software is widely used in professional acoustical design and consultation. However, there are few educational computer programs that are designed mainly for academic teaching of architectural acoustics. Some of these computer programs, such as Acoustic2D and Acoustic3D [J. Turner and N. Barnett, University of Michigan], do not include noise control modeling. A new educational program, Noise Control 2D, is presented. The approach used in the modeling of noise control concepts as well as the design criteria related to this program are explored. The visual user interface and the ability to study the impact of various parameters on room noise are demonstrated. These parameters include architectural factors such as the architectural layout and acoustical parameters such as transmission losses of the room boundaries. Many aspects of noise control in buildings are covered in the program, including noise levels, reverberant and direct sound, NC, NCB, STC, and composite STC.
White whale echolocation pulses in the open sea at the surface and at depth
Authors: Ridgway Sam , Carder Don
Published: October 2013

Previously we reported on the first ever hearing tests of trained cetaceans in the open ocean demonstrating that zones of audibility for sound were just as great throughout the depths to which white whales dive, down to at least 300 m. The tests also showed that the whale’s response whistles changed with increasing depth, overall amplitude decreased and frequency emphasis shifted higher with increasing depth from 5 to 300 m. Subsequently a door was installed in the test apparatus and the whales were taught to whistle in response to the presence of a small cylindrical target 2 m away. When the door opened the whales would utter a train of pulses and then whistle if the target were present. There was no statistical difference in echolocation pulse frequencies or amplitudes between depths of 5, 100, 200, and 300 m. Surprisingly, all pulses recorded at the open ocean test site had peak frequencies between 4 and 40 kHz. These differed markedly from pulses recorded with the same cable and apparatus in San Diego Bay where the whale’s pulses usually exhibited two peaks, one in the 30–80 kHz range and the other often around 100–120 kHz.
Acoustic basis for fish prey selection by echolocating odontocetes
Authors: Au Whitlow W. L. , Benoit-Bird Kelly J. , Kastelein Ronald , van de Heul Sander
Published: October 2013

Acoustic backscatter data were obtained from four fish species, sea bass (Dicentrarchus labras), pollack, (Pollachius pollachius), grey mullet (Chelon labrosus), and Atlantic cod (Gadus morhua), using broadband bottlenose dolphin and narrow-band harbor porpoise signals. The fishes were anesthetized and attached to a monofilament net that was in turn attached to a rotor so echoes could be collected along the lateral axis of each fish. The echo waveforms were complex with many highlights and varied with the orientation of the fish. The highlight structure was determined by calculating the envelope of the cross-correlation function between the incident signal and the echoes. The strongest echo occurred when the incident angle was perpendicular to the long axis of the swim bladder, however, the number of highlights was the fewest at this perpendicular orientation and increased as the fish orientation moved away from the perpendicular aspect. The echo structures were easily distinguishable between species and were generally consistent within species. The highlight structure of the echoes resulted in the spectrum being rippled, with local maxima and minima at different frequencies. However, differences in species were more obvious with the broadband dolphin signal than the narrow-band porpoise signal which had a much lower spatial resolution.
Matched-field replica vector stability in the winter ocean on the New Jersey (USA) shelf—RAGS03
Authors: Mignerey Peter C. , Orr Marshall H.
Published: October 2013

A measure of the environmental influence on matched-field processing is the temporal autocorrelation of the coherent acoustic field passing through a vertical aperture. The matched-field autocorrelation times provide estimates of the time interval over which matched-field replica vectors will remain valid. In December 2003 the Naval Research Laboratory moored three vertical arrays at ranges of 10, 20 and 30 km distant from fixed 300- and 500-Hz CW acoustic sources. The purpose of the experiment was to measure the relationship of array gain to shelf break fluid processes (RAGS03). Data was recorded continuously for more than 20 days. Range and time dependent temporal autocorrelation times derived from this data will be presented and compared to similar measurements made at the South China Sea shelf break during the ONR AsiaEx01 acoustic propagation experiment. Preliminary RAGS03 results show that matched-field autocorrelation times are shortened during strong wind events and that sound speed fluctuations caused by semi-diurnal tidal processes forced quarter-diurnal fluctuations in the matched-field processor output. [Work supported by ONR.]
Correlation of ultrasound-induced premature beats and cavitation in vivo
Authors: Rota Claudio , Raeman Carol H. , Dalecki Diane
Published: October 2013

Exposure of the heart to pulsed ultrasound can produce arrhythmias such as premature ventricular contractions (PVCs). Recently, studies indicate that microbubble ultrasound contrast agents can further increase the sensitivity of the heart to ultrasound by lowering the pressure threshold for PVCs. It was hypothesized that the physical mechanisms for ultrasound-induced PVCs involve acoustic cavitation. To test this hypothesis, a passive cavitation detector (PCD) was used to directly measure cavitation in vivo and to correlate the detected output with the occurrence of a premature beat. Experiments were performed with adult anesthetized mice. Boluses of either a contrast agent (Optison) or saline were delivered via tail vein injections. Pulsed ultrasound exposures were performed at 200 kHz with pulse durations of 1 ms and peak negative pressures ranging between 0.1 and 0.25 MPa. A 5-MHz focused transducer was used as a passive listening device of acoustic signals. For the acoustic conditions above, premature beats were found in all mice injected with Optison and the effect correlated with PCD signal amplitude. Neither premature beats nor cavitation activity were observed among animals injected with saline and exposed to ultrasound. These results are consistent with cavitation as a mechanism for this bioeffect.
A commercialized MEMS microphone for high-volume consumer electronics
Authors: Loeppert Peter V. , Lee Sung B.
Published: October 2013

More than a billion microphones will be used this year in consumer electronic items such as cell phones, PDAs, MP3 players, and cameras. Because standard electret condenser microphones (ECMs) are temperature sensitive, these microphones are either hand placed or inserted with specialized equipment into the applications. MEMS microphones are tolerant of the high temperatures used in a lead-free solder process and hence are ideal for surface mounting with standard pick and place equipment. The challenge has been to develop a stable, low-cost MEMS microphone. This paper will present the design of the Knowles SiSonicTM microphone, which has been successfully commercialized over the past 2 years. Cost is a key driver in this market and total silicon area is a concern; however, the SiSonicTM microphone utilizes separate CMOS and MEMS dies because this has yielded a lower cost than proposed integrated solutions. The MEMS die size is driven by scaling issues and performance requirements. To achieve consistent performance, the SiSonicTM microphone uses a patented free-plate diaphragm. The microphone packaging has been developed to facilitate batch fabrication and a high-speed automated testing system has been developed to deliver a low cost component.
Attack transient for combinations of flue pipes
Authors: Nolle A. W.
Published: October 2013

The tonal attack due to two or more flue pipes sounded simultaneously is compared to that for a single pipe. Attack duration is measured by the times required to progress from 1% to 50% and 90% of final amplitude. Duration can be reduced by the presence of the pipe(s) of higher pitch, because the number of periods in the sound buildup for pipes of a given design does not change greatly with the pitch. Experimental results are from sound records taken in close proximity to the pipes of a Casavant organ having wind chests of Pittman type. The positive division provides stops intended for use with a closed-end 8-foot rank. The great division provides ranks intended for use with an 8-foot (open) principal. A special situation is found in principal pipes near 200 Hz. Sounding one of these with another stop at unison produces an initial sound suggesting a celeste combination. This is found to be the result of a prolonged burst of second harmonic, locked to the growing fundamental, not of frequency difference. This possibility appears in an analytical mode-locking model by Fletcher [N. H. Fletcher, J. Acoust. Soc. Am. 64, 1566–1569 (1978)].
Acoustics of organ reed pipes
Authors: Cox Eric , Rossing Thomas D.
Published: October 2013

In most lingual organ pipes, the reed vibrates against a fixed shallot, and modulates the flow of air passing the shallot into the resonator. We have measured vibrations of plucked and blown reeds of lingual pipes with and without the resonators. We discuss the effects of the acoustic field on the reed vibration and especially the interaction between the reed and the tuned resonator.
NASA’s propulsion airframe aeroacoustics research
Authors: Thomas Russell H.
Published: October 2013

The integration of propulsion and airframe is a fundamental consideration in the design of an aircraft system. Many considerations influence the integration, such as structural, aerodynamic, and maintenance factors. In the future, a focus on the aerodynamic and acoustic interaction effects of installation, propulsion airframe aeroacoustics will become more important as noise reduction targets become more difficult to achieve. In addition to continued fundamental component reduction efforts, a system level approach that includes propulsion airframe aeroacoustics will be required in order to achieve the 20-dB noise reductions envisioned by the aggressive NASA goals. This emphasis on the aeroacoustics of propulsion airframe integration is a new part of NASA’s ongoing acoustics research. The presentation will review current efforts and highlight technical challenges and approaches.
The acoustical equivalence principle for ray tracing
Authors: Floyd Edward R.
Published: October 2013

While the acoustical wave functions for various acoustical problems can be mapped into each other by a coordinate transformation (the acoustical equivalence principle), the corresponding ray tracings cannot be so mapped. Applying the acoustical equivalence principle [A. E. Faraggi and M. Matone, Int. J. Mod. Phys. A 15, 1869–2017 (2000) for the analogous quantum equivalence principle] to the underlying acoustical Hamilton–Jacobi equation for ray tracing renders a modified acoustical Hamilton–Jacobi equation which does obey the quantum equivalence principle. Solutions of the modified acoustical Hamilton-Jacobi equation, which are either acoustical Hamilton’s principal function or the acoustical reduced action (acoustical Hamilton’s characteristic function), are the generators of motion for rigorous ray tracing.
A simple normal-mode model for nighttime traffic noise
Authors: Gilbert Kenneth E. , Waxler Roger , Talmadge Carrick L.
Published: October 2013

At night, traffic noise propagates to long distance via normal modes trapped near the ground in the sound duct created by surface cooling. Consequently, at distances of 500 m or more, traffic noise at any given location is the sum of contributions from many individual vehicles. To predict the band-averaged and time-averaged levels in such situations, one can use an incoherent sum of normal modes. Using an incoherent modal sum, we derive a simple analytic expression for the noise due to traffic on an infinitely long highway. For long highways (10–20 km), it is shown that the controlling factor in the noise propagation is not distance alone, but, instead, the product of the mode attenuation coefficients and the distance from the highway. The predictions for an infinitely long highway are compared with those for a highway of finite length and error bounds are given.
The (energy) loss factors in a dynamic system composed of a master dynamic system and an adjunct dynamic system that are coupled
Authors: Maidanik G.
Published: October 2013

The (energy) loss factor (η) of a dynamic system is defined such that together with the stored energy (E) it yields the power Π dissipated in that dynamic system; (ωη)E=Π, where ω is the frequency and η, E, and Π are functions of ω. An externally driven master dynamic system is defined by the loss factor (η0) and the modal density (ν0). The relevant quantities in the absence of coupling are the external input power (Π0e), the stored energy (E00), and the power (Π00) dissipated. The conservation of energy demands Π0e=Π00. In the presence of coupling Π0e E00 and Π00 become the quantities Πe, E0, and Π0, respectively. The externally driven master dynamic system is coupled to an adjunct dynamic system defined by the loss factor (ηs) and the modal density (νs). The relevant additional quantities are the net power (Πs) transferred from the master dynamic system to the adjunct dynamic system and the stored energy (Es) and the power (Πs) dissipated in the adjunct dynamic system. The conservation of energy demands Πe=Π0+Πs. A number of (energy) loss factors may be defined to describe the energetics of these coupled dynamic systems. A few asymptotic relationships among these loss factors are cited. [Work supported by ONR.]
Sound radiation from rectangular plates with elastic boundary restraints
Authors: Li Wen
Published: October 2013

Sound radiation from rectangular plates is of considerable interest to both researchers and engineers. Different methods and techniques have been developed for determining the sound radiated from plates with various complicating effects. However, the previous investigations are mostly focused on the simply supported plates, although it is widely known that the radiation efficiency of a plate will be strongly dependent upon its boundary condition. In this study, a general analytical method is presented for the calculation of the sound power radiation from a rectangular plate that is elastically restrained along its edges. The vibration of the elastically restrained plates is expressed in terms of a generalized Fourier series expansion. Thus, many of the existing solutions for the sound radiation from the simply supported plates can be directly applied to the plates with general elastic boundary restraints. The radiation characteristics are compared to the plates under different boundary conditions.
Phonemic contrasts in a mutiple talker task with hearing impaired listeners
Authors: Ericson Mark A. , Mishler Pamela J.
Published: October 2013

Word identification ability of mild to moderately hearing impaired listeners was measured in both spatial and nonspatial multiple talker tasks. A digital recording of the modified rhyme test was made for three male talkers. The beginning of the test word in each phrase was synchronized using Cool Edit and equalized to the same average rms power. The phrases were processed for binaural presentation using nonindividualized HRTFs with Tucker Davis Technology System 3 equipment and presented over Sennheisser 600 headphones. The phrases were presented in random order at a self-paced manner. Five mild and five moderately hearing impaired subjects, ranging in age from 24 to 54 years, participated in this study. Results were analyzed by six attributes: place, voicing, nasality, frication, duration, and stops. Phoneme identification performance was ranked based on most salient (most information transferred) to least salient (least information transferred). Spatial separation had no effect on the relative importance of the speech attributes. Duration was the most salient cue for hearing impaired listeners, followed by voicing and frication. Stops and nasality were weak cues and place was by far the least important cue.
Perceptual overshoot in listeners with cochlear implants
Authors: Aravamudhan Radhika , Lotto Andrew J.
Published: October 2013

Perceptual overshoot (PO), a phenomenon in which the boundary for perceived vowel categories shifts as a result of preceding formant transitions, has been demonstrated previously with synthetic vowels in CV contexts in normal-hearing individuals. In one of the previous studies by the author, the same phenomenon was tested with sinewave analogs that mimicked the synthetic vowels. The results demonstrated that PO could be elicited for sinewave analogs after training on categorization of sinewave steady states. These findings suggest that PO may be partly mediated by general processes in the auditory system. In the current study, subjects with cochlear implants were presented with synthetic vowel and sinewave continua with and without transitions. It was predicted that PO would be greatly diminished or absent for this population because of the degraded nature of the spectral input. Implications of the results for theories of speech perception will be presented.
Broadband match-field processing applied in a highly reverberant environment
Authors: Chang Natasha A. , Dowling David R.
Published: October 2013

Application of matched-field processing (MFP) techniques to locate and identify broadband acoustic sources is of interest for studying low event rate cavitation and other hydroacoustic noise sources in water tunnels and other reverberant environments. Here, the main challenge lies in fully exploiting the potentially hundreds of kHz of bandwidth of the cavitation signal to refine the source location estimate. This presentation reports on the preliminary application of MFP in a reverberant enclosure that geometrically mimics the test section of a laboratory water tunnel. For this effort a sound projector and one to four hydrophones are used to make narrow-band and broadband sound field measurements within the enclosure. The requisite field model was initially based on a sum of modes assuming pressure release boundaries, but was empirically modified to accommodate finite impedance boundaries. The model modification allowed the enclosure’s impulse response to be accurately modeled from 3 to 11 kHz and the incoherent Bartlett processor to locate the source when it emitted a series of continuous single tone signals from 3 to 12 kHz. Extension of this effort to signal pulses, a ray-based field model, and water-tunnel testing and sea trials will be discussed as well. [Work sponsored by ONR.]
Frame bulk moduli of air- and water-saturated granular marine sediment models
Authors: Kimura Masao
Published: October 2013

The frame bulk modulus is important in analyzing the acoustic wave propagation in granular marine sediments. The frame bulk modulus is related to the longitudinal and shear wave velocities. We have reported that the derived values of the frame bulk moduli of air- and water-saturated glass beads are different. In this study, the longitudinal and shear wave velocities in air- and water-saturated beach sands, and in same media in vacuum, are measured. Then the frame bulk moduli are derived from the values of these velocities. The results show that the frame bulk moduli in water-saturated beach sands are about ten times greater than that in air-saturated beach sands, and the frame bulk moduli have dependence on the grain size. These phenomena are investigated using the idea of the gap stiffness between the grains.
Noise-induced temporary threshold shifts in pinnipeds: Effects of noise energy
Authors: Kastak David , Southall Brandon , Holt Marla , Reichmuth Kastak Colleen , Schusterman Ronald
Published: October 2013

Auditory pure-tone thresholds were obtained in air and in water from three pinnipeds before and immediately after exposure to octave-band noise. Noise exposure durations were 1.5, 12, 22, 25, or 50 min, and noise levels were 65, 80, or 95 dB referenced to each subjects pure-tone threshold. In air and in water, pre- and postnoise thresholds were obtained at the center frequency of the octave band. In water, thresholds were also obtained at a frequency octave higher than the octave-band center frequencies. Maximum threshold shifts for each species were about 15 dB in air and in water. Under all exposure conditions hearing sensitivity recovered within 24 h. In both media, a curvilinear function best predicted the magnitude of threshold shift from noise energy flux density. At TTS magnitudes greater than 10 dB, this function predicts a 2-dB increase in threshold shift for a 1-dB increase in noise energy, agreeing well with data collected from other mammals.
Noise exposure metrics for auditory and nonauditory damage in aquatic animals
Authors: Hastings Mardi C.
Published: October 2013

The total acoustic energy flux is often used to correlate impacts of different types of sounds having various durations on marine animals. To calculate this metric, one must know both the acoustic pressure and particle velocity. But, in practice, the acoustic pressure is measured usually at just one point and the particle velocity is unknown. The total energy flux is then estimated by assuming the stimulus is an ideal plane wave and calculating the sound exposure level. The inner ears of many aquatic animals, however, respond directly to acoustic particle motion. In addition, because aquatic animals are acoustically coupled to the surrounding water, acoustic particle motion is also critical in estimating sound exposures that may cause damage to tissues outside the auditory system. Thus in noise impact studies, both pressure and local particle velocity must be measured to accurately estimate the total acoustic energy dose received by an aquatic animal. Several case studies taken from the literature will be presented to demonstrate how to estimate acoustic particle velocity from pressure gradient measurements in common aquatic animal testing environments and calculate the total acoustic energy flux.
Random horizontal refraction at long-range sound propagation in the ocean
Authors: Godin Oleg A. , Voronovich Alexander G. , Zavorotny Valery U.
Published: October 2013

Internal gravity waves (IWs) are a major source of sound speed fluctuations in the ocean. For refracted waves in deep water, 3-D and 4-D acoustic effects are caused by cross-range gradients and time dependence of the sound speed. In this paper, IW-induced 3-D and 4-D acoustic effects are studied assuming a continuum of random IWs with the Garrett–Munk spectrum. Fluctuations in azimuthal arrival angles and frequency of tonal signals as well as travel time biases due to horizontal refraction are quantified with a theory which allows one to calculate directly statistical moments of acoustic observables as a weighted integral of an appropriate statistical moment of environmental perturbations. Predictions of the theory are compared to results of Monte Carlo simulations of 3-D and 4-D acoustic effects in the ray approximation. Magnitude of the effects associated with random horizontal refraction at megameter ranges is found to be sensitive to a choice between forms of the Garrett–Munk spectrum which are often viewed as equivalent. Implications of this observation on acoustic characterization of IW fields in deep water are discussed. [Work supported by ONR.]