bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-complexity design schemes for broadband electroacoustic arrays
Authors: Goodwin Michael
Published: October 2013

A variety of methods has been described in the literature for realizing broadband linear electroacoustic arrays, i.e., arrays which exhibit a nearly frequency-invariant response. For example, filter-network beamformers can be designed to achieve a specified beam pattern over a wide frequency range. Some applications, such as low-cost consumer audio products, do not involve strict target pattern requirements and call for lower complexity broadbanding solutions. In this presentation, three broadband array design approaches with low processing overhead and implementation cost are described. The key idea is to configure the array such that its response is essentially a magnification of the response of an individual element; the array geometry and beamformer are designed so as to not introduce directionality. In the first method, the array weights are an approximation of the impulse response of an all-pass filter; in the second method, the array elements are nonuniformly spaced; and, in the third method, arbitrary delays are applied to the elemental signals. Relationships to approaches previously described in the literature are discussed, optimization schemes based on minimizing the array response variation are presented, and the effectiveness of the array designs for realizing a robust broadband wide-angle response is demonstrated.
Three-dimensional microphone array intensity vector sensors for measurement of various acoustical properties in different spatial environment
Authors: Miah Khalid H. , Hixson Elmer L.
Published: October 2013

Precise measurement of different acoustical quantities in different spatial environment has been the key in improving sound-quality and reducing acoustical noise from various sources. In this report, a seven-element 3-D microphone array configuration has been used to measure different acoustical quantities (pressure, particle velocity vectors, intensity vectors, energy density, kinetic and potential energy) in various enclosed environments. Microphones in the array were arranged in an inner and an outer triangular fashion with a reference microphone at the center to address high frequency (1–6 kHz) and low frequency (100–1000 Hz) components of sound signals. Statistical distribution of acoustic field has been used for measurements in large and irregular-shaped room. Statistical distribution of acoustical field using a four-microphone configuration implemented in a previous study (M. W. Budhiantho, Acoustic Velocity Related Distributions dissertation, The University of Texas at Austin, August 1997) has been extended to a seven-microphone configuration in this report. An effort has been made to model acoustical field near the boundaries of an enclosed space (reverberation room). Also 3-D imaging technique of acoustic intensity is also presented in this report.
Performance of an infrasound source localization algorithm
Authors: Szuberla Curt , Arnoult Kenneth , Olson John
Published: October 2013

We present a performance analysis of a method of acoustic source localization based on time difference of arrival (TDOA) information for an arbitrary array of sensors. The method begins with the construction of a vector containing estimates of time delays for each unique sensor pair in the array via cross correlation. An optimization in the space of geographic location and sound speed is then conducted to minimize the difference between the observed vector and one calculated from a search in that space. The technique uses an analytic method of seeding based on the acoustic analog of a light cone. The source localization procedure is tested as a function of a number of parameters, including array aperture, number of sensors, sample rate, signal-to-noise ratio, and signal type. The technique is shown in application to real and synthetic infrasound signals and its statistical behavior is given.
Doppler spreading of aircraft harmonics in a shallow-water channel off Kauai
Authors: Barclay David , Buckingham Michael J.
Published: October 2013

In September 2005, during the Makai experiments off Kauai, a light aircraft acted as a moving sound source over a shallow-ocean channel with a coral-sand bottom. Core samples yielded the porosity, bulk density, grain density, and grain size of the sediment. Acoustic sensors (a microphone in the air and a line of hydrophones in the isovelocity water column) recorded the sound of the aircraft as it flew over the sensor station. At least five engine/propeller harmonics, from 80 to 400 Hz, are present in the spectra of the hydrophone signals. Each harmonic exhibits Doppler spreading, with well-defined spectral peaks appearing on either side of the unshifted frequency. Those peaks with the greatest (up- and down-) shifts are associated with the shallow equivalent rays of normal modes in the water column. Two head-wave peaks, associated with slightly steeper rays, are less up- and down-shifted. Least shifted of all, because of their steep equivalent rays, are peaks due to modes supported by the sea surface and the subbottom, a few meters beneath the seabed. The spectral structure in the Doppler-spread harmonics is the basis of Doppler spectroscopy, an inversion technique for recovering the geoacoustic parameters of the seabed. [Research supported by ONR.]
Estimation of received pulse from sea bottom with a transition layer using elastic finite difference time domain method
Authors: Tsuchiya Takenobu , Endoh Nobuyuki
Published: October 2013

Recently, ocean acoustic thermometry is being planned in shallow water. Characteristics of sound propagation in shallow water are influenced by bottom media because sound propagation is affected by acoustic boundary conditions of the water-sediment interface. To investigate characteristics of sound propagation in shallow water, it is necessary to develop an accurate numerical method to model sound propagation. Elastic finite difference time domain method (elastic FDTD) is very accurate and is useful for range-dependent models in shallow water. Therefore, we calculate the sound waveform reflected from the sea bottom with a transition layer in shallow water using elastic FDTD. It is assumed that a 1.5-kHz transducer is placed at 50-m depth. The influence of the sea bottom with the transition layer is calculated for a 400-m range. To determine the influence of thickness of the transition layer to sound propagation, we calculate sound pulses as transition layers of varying thickness. Results show that fluctuation of the pulse amplitude depends on the transition layer thickness if the thickness is greater than one wavelength. A sea bottom with a transition layer clearly affects sound propagation in shallow water.
Stability of compressional waves in granular media
Authors: McDonald B. Edward
Published: October 2013

Nonlinear compressional waves in a granular medium such as the seafloor are subject to the Hertzian nonlinearity of order 3/2 in the strain rate. As a result, the coefficient of quadratic nonlinearity becomes arbitrarily large at low stress. Two theoretical problems result from the Hertzian nonlinearity: (1) lowest order nonlinearity in the equation of state is no longer quadratic and (2) questions of stability arise when nonlinear steepening occurs arbitrarily fast. A variant of the NPE [McDonald and Kuperman, J. Acoust. Soc. Am. 81, 1406–1417 (1987)] is used to derive a stability theorem for self-similar waves in a granular medium subject to three-dimensional perturbations. When the dominant nonlinearity is of order n between 1 and 3 (n is not necessarily an integer), the result suggests that wave stability is positively correlated with n. The method of characteristics is used to show that where the coefficient of nonlinearity diverges, the wave slope is forced to zero. [Work supported by the Office of Naval Research.]
Benchmarking range-dependent seismo-acoustic propagation problems
Authors: Nielsen Peter L. , Jensen Finn B. , Zampolli Mario , Collins Michael D. , Siegmann William L.
Published: October 2013

Developing the capability to accurately solve range-dependent problems in ocean acoustics has been going on for many years. A milestone in this development was the ASA benchmark effort in 1990 [J. Acoust. Soc. Am. 87, 1497–1545 (1990)], where a set of models was applied to generic range-dependent acoustic fluid problems to establish a set of benchmark solutions for model verification purposes. A further benchmarking effort, which included shear waves in the bottom, was published in 1997 [IEEE J. Ocean. Engn. 22, 226–236 (1997)] involving two seismo-acoustic codes based on spectral-integral techniques and a boundary-element code. Other codes have become available since then for solving general range-dependent elastic problems, either based on marching schemes that ignore backscattering (or adopt a single-scatter approximation) or techniques that solve the full boundary-value problem. In an attempt to establish a set of benchmark solutions for seismo-acoustic problems, we solve several low-frequency elastic problems involving changing bathymetry in multiple layers, and coupling between various wave types, including interface waves. The models in use or used are a parabolic equation model (RAM) and a commercial finite-element model (FEMLAB).
Bathymetric and oceanic variability effects on acoustic propagation metrics in a shelf-break environment
Authors: Oba Roger
Published: October 2013

The interaction of oceanographic variability and bathymetry on acoustic propagation in the littoral is quite complex, and the relative importance is not readily quantified, especially for data-model comparisons. Sound speeds derived from ocean models could be compared directly to experimental sound-speed data, but this is a crude measure of environmental impact on acoustics. Instead, a 300-Hz source in a three-dimensional parabolic equation (PE) acoustic propagation model provides input to proposed acoustic metrics, especially related to array performance, to assess the effects of experimentally derived bathymetry and tide. The metrics can also be used for comparison of an ocean model and experimentally derived sound-speed profiles. Other acoustic mode metrics can be derived and compared to the more computationally intensive three-dimensional PE derived measures. As an example, the Navy Coastal Ocean Model (NCOM), a mesoscale oceanographic model, predicts sound-speed gridded on the order of 5 m in depth and 200 m in range at 6-h updates for the ASIAEx South China Sea site. This can then be used for metric calculations and data-model comparison. [This research is sponsored by the ONR.]
Asymptotic expansions for normal modes in transparent wedge
Authors: Maltsev Nick
Published: October 2013

Asymptotic solutions of exact infinite system of equations for coefficients of angular Fourier harmonics of sound field have been built and computed for an arbitrary transparent wedge. Asymptotic solutions are compared with exact field in the case of two half-spaces and a rectangular wedge.
Polynomial chaos expansions for travel time and amplitude uncertainty in acoustic time series in ocean waveguides
Authors: LePage Kevin D.
Published: October 2013

Polynomial chaos (PC) techniques have shown themselves to be a powerful technique for the estimation of the statistical properties of ocean acoustic propagation for situations where the vertical and horizontal structure of sound speed uncertainty can be specified in terms of empirical orthogonal functions (EOFs) with known amplitude probability distribution functions. Here we extend the CW solutions for the statistical properties of the normal models describing the acoustic field in the presence of internal waves with Gaussian distributed EOF descriptions to the time domain to describe the scintillation of the acoustic time series. Results are compared to exact solutions as well as to estimates based on the adiabatic approximation. Results show that the PC solutions do a much better job of capturing the true variability of the exact solutions for the time series variability than the adiabatic approximations does. [Work supported by ONR.]
Relationship between ventilation, air quality, and acoustics in ‘‘green’’ and ‘‘brown’’ buildings
Authors: Khaleghi Alireza , Bartlett Karen , Hodgson Murray
Published: October 2013

This paper discusses a project involving direct monitoring of ventilation, indoor-air quality, and acoustical quality in ‘‘green’’ and ‘‘brown’’ buildings on the UBC campus. The objective was to determine the relationship between these various environmental factors, and the implications of the results for the ventilation-system concept/design, especially in green buildings. The buildings studied, the measurements performed, and the main results are described. The lessons learned about ventilation design are discussed.
Acoustic and thermal evaluation low-cost dwelling, a case study in Curitiba, Brazil
Authors: Zannin Paulo H. , Krueger Eduardo
Published: October 2013

The present paper presents acoustic and thermal performance evaluations carried out in low-cost houses located at the Technological Village of Curitiba. Two dwellings were evaluated, which were built according to different building systems: (1) the building system Batistella, built with prefabricated modules and elements, composed of reforestation wood, and (2) the building system Constroyer, composed of EPS plates, framed in a welded iron mesh, with structural plastering. For the thermal performance evaluation, it was verified that the materials used in the envelope were quite significant for controlling heat gains and losses through the building elements as well as for regulating heat storage. In this case, the system with highest thermal inertia presented better results. Results showed that both building systems had poor acoustic performance, characterized by a low weighted apparent sound reduction index of the facade R′w=18 dB. The German DIN 4109 Norm recommends R′w=30 dB. The weighted apparent sound reduction index measured for internal walls was R′w=25 dB and R′w=30 dB, for the building systems Battistela and Constroyer, respectively. The minimum required by German VDI 4100.
Design of the diffuser with hemispheres using 1:10 and real scale models
Authors: Sato Shin-ichi , Jeon Jin Yong
Published: October 2013

Sound diffusion by a wall structure is one of the main concerns with respect to the sound quality of concert halls. To quantify the sound diffusion of an actual hall from in situ measurements, the relationship between the scattering coefficient and the acoustical parameters measured in the laboratory should be investigated first. In this study, the scattering coefficient and acoustical parameters of the diffusers with hemisphere were investigated. The diameter, density, and the arrangement pattern of the hemisphere were investigated in terms of the scattering coefficient and the parameters obtained from the impulse response including temporal diffusion [H. Kuttruff, Room Acoustics (Elsevier Science, London, 1991)]. The results of measurements in 1:10 scale reverberation chamber with the same scale diffusers were verified by real scale results. Sound scattering index for reverberation chamber, which quantifies the scattered sound field, was proposed. The optimum condition of the hemisphere diffuser specification maximizing the effect of scattering on a sound field was also investigated.
Simulation of in situ measurement of diffusion and scattering coefficients
Authors: de Vries Diemer , Kuster Martin , Joeman Naziema , Schreurs Eric
Published: October 2013

Since it has become clear that simulation of the acoustical properties of a room is not successful unless also nonspecular reflections are taken into account, the determination of diffusion and scattering coefficients of boundary profiles is a hot topic in room acoustics research. Measurement of the impulse response of a boundary along a planar array of microphone positions enables us to calculate these coefficients in situ, avoiding the drawbacks of laboratory measurements (necessity of scale modeling, limited value of results for practical situations). Array technology makes it also possible to extrapolate the measured responses to the boundary surface, thus creating an acoustical image of the boundary. Next, scattering objects can be virtually added to this image and the impulse response of the modified configuration at the array position can be obtained by inverse extrapolation. This way, the effect of adding an object to a real environment is simulated in a highly realistic way. For several (virtual) modifications of the original boundary, diffusion and scattering coefficients have been calculated and compared. Also, listening tests have been carried out to assess the perceptual significance of the modifications.
Effects of specular and diffuse reflections on perceived music quality
Authors: Smitthakorn Pattra , Gold Martin A. , Siebein Gary W. , Kinzey Bertram Y.
Published: October 2013

The purpose of this study was to investigate the effects of temporal distribution of diffuse and specular reflections on the perceived acoustic qualities of music performance. Sets of impulse responses were designed with different temporal distributions of early acoustic energy (specular and diffuse reflections). Then, three types of anechoic sound sources, orchestral music, trumpet, and piano, were convolved with the designed impulse responses. The results from the listening tests revealed that different room environments were needed to acoustically support different source characteristics: (1) A large number of diffuse reflections arriving within 40 and 80 ms of the direct sound improved perceived intimacy, texture, and overall impression for all sound sources; heightened perceived clarity for trumpet and piano; and reduced perceived glare for trumpet. (2) Diffuse reflections arriving between 80 and 160 ms of the direct sound preserved perceived reverberance and reduced perceived echoes as opposed to specular reflections arriving at the same time period. The results of this study indicate that music performance halls should be designed to include diffuse reflections from surfaces within the 80-ms time period to achieve preferred texture, intimacy, clarity, and overall impression and in the 160-ms time period to reduce echoes.
The angular distribution of sound incident on a panel or opening
Authors: Davy John L. , John Thomas K.
Published: October 2013

A theoretical method has been developed for predicting the directivity of the sound that is radiated from a panel or opening excited by sound incident on the other side. This directivity needs to be known when predicting the sound level at a particular position due to sound radiation from a roof, wall, ventilating duct, or chimney flue. The method uses a two-dimensional strip model and the low-frequency result for a square piston. It was found necessary to use a weighting function in order to account for the angular distribution of the incident sound. Initially a cosine squared weighting function with a weighting angle parameter was chosen and the weighting angle parameter was varied in order to obtain the best agreement with experiment for the particular situation. This talk will describe the theoretical development of weighting functions, which are based on the actual physics of each situation. Situations that are covered include an opening or panel on the surface of a room and an opening at the end of a duct. The method will be compared with published experimental results on the directivity of the forced sound radiation from panels and the sound radiation from openings.
Vertebrate vocal production: Themes and variations
Authors: Fitch W. Tecumseh
Published: October 2013

Most terrestrial vertebrates produce sound using a vocal system of lungs, larynx, and vocal tract, already in place in lungfish ancestral to all tetrapods. Despite the conservative nature of this basic system, there are a wide variety of modifications of the structure of the vocal system that appear to be linked to vocalization. In addition, several clades have evolved novel vocal production systems, including the avian syrinx and the odontocete nasal sac system. In this overview I will focus on the ‘‘standard’’ vertebrate system, discussing modifications of the vocal folds to produce high-pitched (e.g., bats and some primates) or low pitched (e.g., roaring cats) vocalizations, showing endoscopic videos of such unusual vocal folds in action. Moving to the vocal tract, a number of anatomical modifications result in vocal tract elongation, thus lowering formant frequencies. The flexible, dynamic nature of the mammalian vocal tract is illustrated with cineradiographs of vocalizing mammals. Finally, I will discuss the enigmatic existence of air sacs attached to the larynx or vocal tract. Vocal air sacs have evolved in parallel in many different species, in all classes. Despite a variety of plausible hypotheses, the function(s) of these air sacs remains poorly understood.
Simulation of Siberian tiger vocalization
Authors: Titze Ingo R. , Alipour Fariborz , Fitch Wm. Tecumseh , Hunter Eric J. , Walsh Edward J.
Published: October 2013

The excised larynx of a Siberian tiger, which died of natural causes, was studied on a laboratory bench. Pressure-flow relations were determined, as well as modes of vibration of the vocal pads. In addition, CT scans of the animal were made available (from previous health examinations), which allowed the vocal-tract airway to be quantified. The larynx and vocal tract-data were then used to simulate the sound production of the animal. Results showed that multiple tissue modes are excited to produce a tiger roar, and that the production is highly efficient for aerodynamic to acoustic energy conversion. Scaling factors for linear dimensions of the larynx and vocal tract are derived to compare the phonation of this large mammal to human phonation.
Birdsong: The role of the vocal tract
Authors: Suthers Roderick A.
Published: October 2013

The avian vocal organ, the syrinx, is unique among vertebrates in its morphology and location at or near the base of the trachea. In oscine songbirds, two independent sound sources share the same vocal tract. Despite a growing knowledge of the neural and syringeal mechanisms underlying song, the acoustic role of the suprasyringeal vocal tract in modulating birdsong is still poorly understood. During song, the beak opening, or gape, is typically positively correlated with the dominant frequency of the vocalization, but the mechanism by which beak gape influences vocal tract acoustics is controversial. X-ray cinematography of singing birds reveals song-related movements of the hyoid apparatus and larynx that cause the volume of the upper vocal tract to vary inversely with the songs fundamental frequency. At low fundamental frequencies, the oropharynx and cranial end of the esophagus expand to form a single large chamber, the volume of which is reduced at higher frequencies by collapse of the esophagus and reduction of the oropharyngeal cavity. A computational acoustic model indicates that birds actively tune the volume of their oropharyngeal-esophageal cavity so that its major resonance tracks the fundamental frequency of the song. [Work supported by NIH.]
Odontocete nasalizations: Morphology, physiology, and evolution of sonar signal generation in toothed whales
Authors: Cranford Ted
Published: October 2013

The odontocete nasal apparatus contains tissue complexes that generate a variety of sounds. Sounds are produced by moving air across the phonic lips, internal structures that were formed by the invagination of the ancient nasal openings. X-ray computed tomography shows this sound generation complex bilaterally in all odontocetes except in sperm whales, where it is unilateral. Two bottlenose dolphins provided simultaneous bilateral recordings of internal nasal cavity pressure and nasal tissue motion. Small catheters measured pneumatic pressure changes within each bony nasal passage; high-speed video endoscopy recorded motion at both pairs of phonic lips; and two hydrophones revealed acoustic pressure during target discrimination. Sonar pulses can be generated at the left and right phonic lips, independently or simultaneously. Air pressure in both bony nasal passages rises and falls together, even if the activity patterns at the two pairs of lips are different. Increasing pulse repetition rate or sound pressure levels are all normally accompanied by increasing nasal air pressure. The bilateral arrangement of sonar sources in the odontocete nose provides a basis for reinterpretation of previous findings; reevaluation of physiologic limits and on pulse repetition rate, signal bandwidth, frequency composition, and transmission beam geometry; and the evolution of this system.
Is the squirrel monkey larynx lateralized biomechanically?
Authors: Brown Charles H. , Alipour Fariborz
Published: October 2013

Squirrel monkey larynges were dissected, mounted on a pseudotracheal tube, and phonated via the flow of compressed heated and humidified air. Synchronized audio and video signals were digitized and analyzed with a signal processing workstation. Image analysis algorithms measured the change in glottal area due to the movement of the left and right vocal folds, respectively, and measured the change in location of both vocal folds during phonation. The results show that the squirrel monkey larynx is capable of both unilateral and bilateral oscillation. In the unilateral case, oscillation is virtually confined to the left vocal fold. The converse of this has not been observed. In the case of bilateral oscillation, the folds may oscillate synchronously in phase, asynchronously out of phase, or at different fundamental frequencies. The results are consistent with the idea that the biomechanical properties of the left and right vocal folds differ with the left fold capable of oscillation at lower subglottal pressures and greater amplitudes. Changes in vocal fold elongation and adduction change the coupling between the two folds and produce different regimes of oscillation. Squirrel monkeys appear to employ intentional shifts between different regimes of phonation to expand the size of the vocal repertoire.
Syllable chunking in Bengalese finches in a multi-tutor environment
Authors: Takahasi Miki , Tomizawa Iori , Okanoya Kazuo
Published: October 2013

Experiments in birdsong learning have traditionally involved one tutor, usually the father, and the proportion and accuracy of note copying are discussed as indexes of song learning. But in the wild, there are several conspecific males around song-learning pupils. To test song learning under naturalistic situation, 11 male and ten female Bengalese finches were kept in a large flight cage containing ten pot-shaped nests. Seventy-eight chicks were born in this aviary over an 18-month period. We recorded the full songs of male birds after they had matured, and compared the songs between offspring and the original adult males. Most of them learned their songs from one or two tutors and some learned from three or four tutors. When a bird learned from multiple tutors, each of these tutor songs was copied in chunks and within a chunk the order of the song elements was the same as that observed in the tutor male. Furthermore, Bengalese finches change the order of chunks as they sing, and it was possible to express the rule using a finite-state syntax. Therefore, Bengalese finches have an innate universal grammar allowing them to construct a finite-state syntax from multiple sources. [Work supported by JSPS and JST.]
A study on ultrasound parameter specification by temperature rise
Authors: Inoue Hiroshi , Yamaya Chiaki
Published: October 2013

So far, temperature rises by absorption of ultrasound have been researched to secure the safety of the ultrasonic diagnostics and the application of ultrasonic therapy. This research is intended to develop a numerical simulation method that is applicable to estimation of medium constants, e.g., the absorption coefficient, using the temperature rise by the ultrasound. The temperature rises have been measured using a micro-thermocouple with high spatial resolution. Three-dimensional simulation using finite-difference time-domain (FDTD) method, which combines ultrasonic propagation and heat conduction, i.e., ultrasonic and temperature fields, is developed. At the first stage, two-dimensional analyses of ultrasonic fields were different from theoretical and experimental values. Therefore, we developed three-dimensional analysis. Time responses and spatial distributions of temperatures of the experiments and simulations were compared. Spatial distributions of temperature that were obtained using the FDTD simulation correspond qualitatively with those obtained by experiment, taking into account the thermocouple artifact. The possibility of estimation of medium constants is therefore suggested.
Twenty years’ development of acoustic microscopy for medicine and biology
Authors: Saijo Yoshifumi , Sasaki Hidehiko , Tanaka Motonao , Hozumi Naohiro , Kobayashi Kazuto , Dunn Floyd
Published: October 2013

Since 1985, scanning acoustic microscope (SAM) systems for medicine and biology has been developed and have been equipped for investigation of acoustic properties of various organs at Tohoku University. There are three objectives of SAM for biomedicine. First, it is useful for intraoperative pathological examination because staining is not required. Second, it helps understanding lower frequency ultrasonic images such as echography or intravascular ultrasound because SAM provides microscopic acoustic properties. Third, it provides information on biomechanics of tissues and cells. The most important feature of our SAM is to measure attenuation and sound speed of soft tissues by analyzing the frequency-dependent characteristics of amplitude and phase. Recently, a new-concept acoustic microscopy using a single pulsed wave instead of burst waves used in conventional SAM systems was proposed. Application of SAM has also been broadened and it covers not only myocardium and atherosclerosis in cardiology but also skin, bone, cartilage, tendon, and muscle in dermatology and orthopedic surgery. Higher resolution acoustic microscopy with over 500 MHz enabled us to visualize cultured cells and it can be applied for quality assessment of regenerated skins and cartilage. Impedance acoustic microscopy and 3-D acoustic microscopy are developed for in vivo tissue imaging.
VHF/UHF range bioultrasonic spectroscopy system and method
Authors: Akashi Naoyuki , Arakawa Mototaka , Odagawa Hiroyuki , Sannomiya Toshio , Kushibiki Jun-ichi , Chubachi Noriyoshi , Dunn Floyd
Published: October 2013

We developed the bioultrasonic spectroscopy system and method for doing ultrasonic tissue characterization studies in the VHF and UHF ranges. The system can determine the frequency characteristics of bulk acoustic properties of the sound velocity, attenuation, acoustic impedance, and density simultaneously by an ultrasonic transmission line comparison method using pure water as the reference, and using rf tone burst pulse signals. A biological tissue/liquid specimen is sandwiched between the parallel surfaces of buffer rods having ZnO piezoelectric film transducers on their opposite ends. Measurements are conducted with a typical thickness of 0.1 to 1 mm in the frequency range up to 700 MHz, and in the frequencies higher than 500 MHz, with a thin layer of specimen, several micrometers, operating in the multiple interference method. The system was applied for demonstration to measure the acoustic properties of bovine tissues, egg yolk and albumen, and aqueous solutions of biomacromolecules such as bovine hemoglobin and sugars in the frequency range 10 MHz to 1.6 GHz. The system and methodology will enable us to provide basic data for understanding the interaction of high-frequency ultrasonic waves with biological media and to make contributions to the establishment of the scanning acoustic microscope in the fields of biological and medical sciences.
The impact of Floyd Dunn’s research on echocardiography and myocardial tissue characterization
Authors: Miller James G.
Published: October 2013

By the mid-1970s our lab had demonstrated that alterations in myocardium as a result of mature infarction could be quantified ultrasonically, with increased attenuation correlating with the extent of myocardial damage assessed in the same sites by depletion of creatine kinase. [Mimbs et al., Circ. Res., 41, 192–198 (1977)]. The Feigenbaum laboratory made the qualitative observation that zones of infarct were ‘‘more echo producing’’ than nearby zones. [Rasmussen et al., Circulation 57, 230–237 (1978)]. A 1973 article from Floyd Dunn’s laboratory [S. Fields and F. Dunn, J. Acoust. Soc. Am. 54, 809–812 (1973)] provided the basis for understanding these and many future developments in echocardiography and myocardial tissue characterization. In that seminal paper the authors state, ‘‘The magnitude of the echoes received is directly related to the preferred orientation and amount of collagen....’’ We subsequently demonstrated the causal relationships between regional myocardial collagen content and both attenuation and backscatter. We also confirmed the Dunn prediction of anisotropy of attenuation, backscatter, and phase velocity. [Work supported by Grant NIH-R37-HL40302.]
Theoretical analysis of local attenuation approximations when calculating scatterer correlation length
Authors: Bigelow Timothy A. , O’Brien William D.
Published: October 2013

Determining the correlation length of ultrasound scatterers has shown potential in many tissue characterization applications. Accurate estimates of scatterer correlation length can only be obtained after correcting for focusing, frequency-dependent attenuation along the propagation path (total attenuation), and frequency-dependent attenuation in the region of interest (local attenuation). In order to correct for the local and total attenuation, an approximation is required because uncertainties in tissue attenuation can easily be 0.5 dB/cm-MHz, or greater, even for the same tissue type [J. Acoust. Soc. Am. 64, 423 (1978)]. Earlier simulation results demonstrated that the most robust approximation for the local attenuation while completely compensating for total attenuation and focusing for weakly focused sources was to assume a finite frequency dependence of ∼0.8 dB/cm-MHz independent of the true attenuation of the tissue for attenuation values between 0.05 and 1 dB/cm-MHz. The goal of the present study was to investigate the theoretical basis for this approximation so that the results could be applied to other ranges of attenuation values. The theoretical analysis was then compared to the simulation results to validate the conclusions. [This work was supported by the University of Illinois Research Board and the University of North Dakota School of Engineering and Mines.]
High-frequency pulse-compression ultrasound imaging using an 18-MHz annular array
Authors: Mamou Jonathan , Ketterling Jeffrey A. , Silverman Ronald H.
Published: October 2013

High-frequency ultrasound (HFU) allows fine-resolution imaging at the expense of limited depth-of-field (DOF) and shallow acoustic penetration. Coded-excitation imaging allows a significant increase in the signal-to-noise ratio (SNR) and acoustic penetration depth. A 18-MHz, five-element annular array with a focal length of 31 mm and a total aperture of 10 mm was made using a 25-μm thick membrane. To excite the PVDF-TrFe transducer, an optimized 8-μs linear chirp spanning 6 to 30 MHz was uploaded into a waveform generator. The optimal chirp design was deduced from ex vivo experiments and computer simulations. Images of a seven-wire phantom were generated. The 25-μm wires were spaced in 1-mm axial and lateral increments. All 25 transmit/receive signal combinations were digitized and postprocessed for compression and synthetic focusing. Compression consisted of linearly filtering the signals with a mismatched filter. The mismatched filter was the time-reversed excitation chirp modulated by a Dolph-Chebyshev window. Marked image-quality improvements were demonstrated in images of ex vivo cow eyes. Results of this study demonstrate that the DOF can be improved by a factor of 3 and SNRs, after compression, can be improved by 24 dB.
Spatial distributions of acoustic parameters in high-intensity focused ultrasound fields
Authors: Khokhlova Vera A. , Bessonova Olga S. , Canney Michael S. , Bailey Michael R. , Crum Lawrence A.
Published: October 2013

Different peak and average acoustic parameters determine the efficiency of different physical mechanisms of high-intensity focused ultrasound (HIFU) interaction with biological tissue. Spatial distributions of these parameters are therefore important for transducer calibration and extrapolation of measurements in water to application in tissue. In the case of linear focusing, all parameters of the acoustic field can be obtained from the spatial distribution of the wave amplitude. However, in nonlinear focused beams, each parameter has its own characteristic spatial structure, which changes with the increase of the HIFU power level. This work compares the focal size and location calculated for the peak positive and peak negative pressure, mean intensity, and effective acoustic energy absorption in water and in tissue. Numerical solutions, obtained with the KZK-type model, are analyzed for various regimes of linear, quasilinear, and strongly nonlinear propagation which includes formation of shocks. The results of simulations are validated by comparison with measurements performed with a fiber-optic probe hydrophone in water and in a tissue-mimicking phantom. The peak positive pressure and effective absorption are finely focused, whereas the negative pressure, responsible for cavitation, is broad and displaced towards the transducer. [Work supported by NSBRI SMS00402, RFBR, and NIH DK43881.]
Finite aperiodic model of human lung
Authors: Wochner Mark S. , Ilinskii Yurii A. , Hamilton Mark F. , Zabolotskaya Evgenia A.
Published: October 2013

This work is focused on studying the dynamics of the human lung in response to low-frequency sound. The model developed uses individual alveoli as the basic unit cells, which are represented as truncated octahedra [Y. C. Fung, J. Appl. Physiol. 64, 2132 (1988)]. Having 14 faces, this polyhedron possesses the smallest surface-to-volume ratio of any polyhedron capable of filling three-dimensional space. Unlike previous quasistatic models of this type, typically used to predict elastic properties of the lung, ours is a dynamical model. Mass is concentrated at the vertices of the polyhedra. Viscoelastic properties of the collagen and elastin in lung tissue are taken into account using a Kelvin model that is augmented to account for nonlinear elasticity. The Kelvin elements connect the point masses along the edges and across the faces of the polyhedra. Although not yet taken into account, the model permits inclusion of alveolar ducts by opening or closing selected faces of the polyhedra to accommodate airflow. Numerical simulations of small alveolar clusters subjected to different excitations and geometric constraints will be shown. [Work supported by ONR and ARL IR&D.]
Infinite periodic model of human lung
Authors: Ilinskii Yurii A. , Wochner Mark S. , Hamilton Mark F. , Zabolotskaya Evgenia A.
Published: October 2013

As described in a companion abstract, an investigation is underway to develop a bioacoustic model of human lung. In parallel with the numerical model described in the companion abstract, a semianalytic model is being developed. The basic unit cell, a truncated octahedron, is the same. In contrast here, the medium is assumed to be infinite in extent. The resulting lattice possesses cubic symmetry, and, for homogeneous deformation, all material properties are determined by a single unit cell. Deformation of the unit cell is determined by the 24 vertices of the polyhedron, only 6 of which are independent. In this presentation we discuss quasistatic deformation of the discretized medium, and thus ignore inertia and energy dissipation. An analytic model for the nonlinear elasticity of collagen and elastin is used to determine the stiffnesses of the springs connecting vertices of the polyhedra. Minimization of the potential energy for a given macroscopic deformation permits calculation of microscopic deformation within the unit cell, which in turn determines the stresses and therefore the elastic constants. Sample calculations will be presented, including the longitudinal and transverse wave speeds in the medium as functions of direction and orientation. [Work supported by ONR and ARL IR&D.]
Detecting spatially resolved inertial cavitation with a diagnostic ultrasound system
Authors: Farny Caleb H. , Cleveland Robin O. , Holt R. Glynn , Roy Ronald A.
Published: October 2013

The onset and presence of inertial cavitation in high-intensity focused ultrasound (HIFU) therapy has been identified as an important indicator of energy deposition for therapy planning. A common technique for detecting inertial cavitation is passive cavitation detection, where broadband noise emissions indicative of inertially driven bubbles collapses are detected using a fixed focus transducer. This technique is suboptimal for clinical applications, because most passive cavitation detector (PCD) transducers are tightly focused and thus afford limited spatial coverage of the HIFU focal region. Here, we report on efforts to use a diagnostic ultrasound system as a PCD by operating in passive mode and filtering out the main HIFU frequencies. This approach allows for spatially resolved detection of inertial cavitation throughout the focal region while being insensitive to scattering from voids or bubbles. [Work supported by the Dept. of the Army and the Center for Subsurface Sensing and Imaging Systems.]
Image processing for scanning-type biological ultrasonic microscope considering its beam characteristics
Authors: Kobayashi Kazuto , Hozumi Naohiro , Ohtsuki Shigeo
Published: October 2013

We have been developing a biological ultrasonic microscope with a high lateral resolution. An acoustic pulse is transmitted by a scanning transducer to a substrate on which a thin slice of a tissue is embedded. The transducer has a minute curvature in order to focus an acoustic beam with a high frequency component. It may be fabricated by MEMS technology; however, from the point of view of engineering, it may not be easy to guarantee the reproducibility of beam pattern as specified. In a high frequency range, a small error in fabrication will lead to a big difference in beam pattern, which strongly affects the observed image. Using newly proposed methodology to observe a well-defined pin-hole, we found that each commercial single probe transducer with the same specification has a unique beam pattern. In addition, the pattern was not always concentric. Consequently, we proposed a method to compensate the image that was obtained using an eccentric beam pattern. A clearer image was successfully obtained after the compensation.
Vibrations of a harp soundbox: Experiment and finite-element analysis
Authors: Waltham Chris , Kotlicki Andrzej
Published: October 2013

A medium-sized lever harp of proven design has been built. At each stage of construction, the components have been subjected to experimental modal analysis, using an impact hammer and small accelerometer, and also Chladni patterns. The results have been compared to a corresponding sequence of finite-element calculations. The aim is to build a picture of how the various ingredients—soundboard, veneer, ribs, soundbox, access holes, string tension, etc.—interact with each other to produce an acceptable instrument. Ultimately one would like to create a set of desiderata for the design and manufacture of harp components in a similar manner to that already achieved for, say, the violin.
The nonlinear motion of harp strings
Authors: Waltham Chris , Kotlicki Andrzej
Published: October 2013

The harp is an instrument with a set of plucked strings that excite the sound board directly, without the medium of a bridge. The strings are positioned at an acute angle to the plane of the sound board. The quality of the sound produced depends on the motion of the string and its interaction with the resonances of the sound board. String and sound board motions have been studied using small, infrared position sensors. The results are compared to those of a simple nonlinear model based on the measured elastic properties of the string materials and those of the soundboard. We will also describe the construction and calibration of the position sensors.
On Dagestan tamur acoustical features
Authors: Aliev Shamil , Myshinsky Ernst , Pyshin Alexander
Published: October 2013

The study of the tamur, a national Dagestan two-stringed musical instrument played by plucking with narrow body gouged from linden wood, is presented. Distinctive features of the tamur sound making process are described. The resonance properties of the tamur body, that is, the mechanical resonance system, are determined. Also the resonance properties of air volume inside the tamur body, that is, an acoustic resonator, are determined. An interaction of the tamur body mechanical vibration and air volume inside the body oscillation are discussed. Tamur body sound radiation dependencies on frequency are studied. The resonance properties of instrument strings and purity of their sounding are determined. The assessment of efficiency of transformation string oscillations into tamur sounding board oscillations (body mechanical impedance) is discussed. The elastic and acoustic constants of linden, that is, the wood material of the tamur body made by gouge, are determined. The logarithmic decrement of tamur sounding board oscillations is determined. The typical spectra of tamur sounding are analyzed.
Comparing harmonic reinforcement in the Octet’s Mezzo and a typical Strad-model violin
Authors: Voskuil Duane , Hutchins Carleen M.
Published: October 2013

Many players and listeners maintain the Octet violins have a fuller sound than conventional instruments. Preliminary data indicate Octet violins may better embody some resonant intervals that make this more likely. A theory is presented based on a study comparing the Octet’s Mezzo and a Strad-model violin, concluding that C. M. Hutchin’s original design principle for the Mezzo fortuitously related A0 to A1 as an interval of a fifth near the two open middle strings, allowing more constructive wave reinforcement than conventional violins. The theory considers other intervals, seeking to maximize harmonic reinforcement by modifying instruments, (1) so that every bowed note is reinforced by an activated wood or air resonance by placing the notes fundamental and overtones close enough to a resonant frequency to activate it, (2) so that two resonances constructively interfere when they are simultaneously activated because they are separated by a harmonic interval, and (3) so that as many higher mode resonances as possible are activated by upper partials of the bowed notes harmonic series.
Spectral method applied in physical modeling synthesis of plate
Authors: Zhang Lin
Published: October 2013

As a well-applied method in scientific computation, spectral methods have properties like higher order accuracy, nonlinearity expandability, and memory saving. By an example, this work will explore the potential of its application into physical-based sound synthesis With background work of finite difference on wave equation, spectral differentiation is further applied in space of discretization of partial difference equation (PDE). General plates (including membrane) percussion models are created numerically presenting the wave propagation inside of plate. According to two different dimensions (rectangular and circular), Fourier or Chebyshev interpolations are applied. In addition, stiff system is introduced by adding sizzlelike partials onto plate model (sizzled cymbals in jazz music) and complex collision phenomena (for example, ride cymbals). Problems such as stability condition take an important position in analysis. The algorithm is to generate high-quality multichannel audio outputs for musical purpose. For the continuity and expandability as application module, parallel computation programming is taken as the focus of final implementation on a Sun Bluefire E15K shared memory machine [Work supported by EPCC.]