bluuebunny/crossref_metadata_2025 huggingface dataset:
Synchronized optical and acoustical measurements of trombone embouchure.
Authors: Bulen Jay C.
Published: October 2005

Outward striking- and inward striking-reed models have been proposed for representing brass players’ lips [Sanoyesi et al., Acustica 62, 194–210 (1987)]. The models differ in the predicted relationship between mouthpiece pressure and lip displacement. To investigate this, Yoshikawa measured the phase relationship between mouthpiece pressure and lip strain as indicated by a strain gauge taped to the upper lip [J. Acoust. Soc. Am. 97, 1929–1939 (1995)]. However, the relationship between strain and displacement have not been experimentally established, and Yoshikawa’s assumed correspondence ‘‘is still a hypothesis which needs refinement’’ (p. 1931). Optical measurements are required. Synchronized optical and acoustical measurements of a trombonist’s embouchure have been made under performance conditions, using an adaptation of techniques described in Sercarz et al. [Am. J. Otolaryngol. 13, 40–44 (1992)]. Using strobed videoscopy, individual video fields are coordinated with mouthpiece pressure by means of timing signals. The phase relationship between mouthpiece pressure and lip displacement will be reported for a variety of fundamental frequencies and intensities. In addition, estimates will be presented of the aperture area and the mouthpiece volume swept out by the lips.

The goal of this informal workshop, a continuation of Session 1aSC, is to bring together several researchers working on various aspects of voice perception. Historically, the study of voice has been treated as a more-or-less autonomous area quite distinct from other research problems in speech and hearing sciences. In this workshop, some of the traditional problems of voice classification and perception will be discussed and reviewed and then these efforts will be related to recent findings in speech perception and spoken word recognition which have shown important dependencies between traditional voice parameters and perceptual analysis of the speech signal. The contributors to the session include: Jody Kreiman, Diana VanLancker, Keith Johnson, Robert Remez, Peter Jusczyk, and David Pisoni. Please bring your slides and overheads and join in the discussion on some long-standing problems related to the ‘‘indexical’’ and ‘‘linguistic’’ functions of speech. For further information about this informal workshop, please feel free to contact D. B. Pisoni via E-mail: pisoni@indiana.edu. Everyone with an interest in speech perception, production, and spoken language processing is welcome to attend and contribute to the discussion of these problems.
Pitch, periodicity, and the brain.
Authors: Hartmann William M.
Published: October 2005

The perception of pitch forms the basis of musical melody and harmony. It is also the most precise of all our human senses. With imagination, this precision can be used experimentally to investigate the functioning of the auditory system. The Indianapolis tutorial will present auditory demonstrations from the zoo of pitch effects: pitch shifts, noise pitch, virtual pitch, dichotic pitch, and the pitches of things that are not there at all. The tutorial will introduce models of auditory processing, derived from contemporary psychoacoustics and auditory physiology, and will test these models against the experimental effects. It will conclude by describing the critical role played by pitch in the human ability to disentangle overlapping voices, as modeled by current work on artificial intelligence.
An overview of the acoustical effects of an audience.
Authors: Bradley J. S.
Published: October 2005

This paper reviews the various effects of an audience on the acoustical properties of an auditorium. At the most basic level, the total sound absorption of both occupied and unoccupied chairs can be predicted in terms of the perimeter/area ratio of audience seating blocks. Using this technique, reverberation chamber measurements of occupied chairs can be used to estimate the reverberation times of fully occupied halls. This technique has been extended to provide estimates of typical sound-absorbing properties of occupied chairs for all sizes of seating blocks. Partially occupied seating areas present further problems. Audience effects on early- and late-arriving sound levels and early/late sound ratios are related to the geometry of the halls as well as to changes in the total sound absorption. Interaural cross correlations and lateral energy fractions are not greatly influenced by the presence of an audience. Changes to the more detailed spectra of the direct and early arriving sound show that the effect of the audience on the seat dip attenuation can vary with the type of seating as well as other properties of the hall.
Partially coupled chambers in auditorium design.
Authors: Johnson Russell
Published: October 2005

Our consulting group has completed 12 concert rooms or opera houses with controllable partially coupled chambers, and we have three either under construction or on the drafting boards. This paper provides a very brief overview of this approach to auditorium design and gives a rough idea of how this design feature might evolve during the next 5 years, with some reference to adjustability of the cubic volume of the primary chamber, and to the location of the openings into the secondary chamber.
Computational modeling of multiple-pass perforated tube silencers in the time domain.
Authors: Dickey N. S. , Selamet A.
Published: October 2005

To reduce the low-frequency radiated noise from automotive engines, intake and exhaust system silencers often employ perforated tube elements. These geometries commonly consist of one or more perforated tubes aligned axially within an external duct having a length significantly larger than any cross dimension. For such a silencer, the low-frequency acoustic performance may be analyzed by considering one-dimensional flow in each of the passages, coupled by the communication between regions through the perforate interface. The behavior of these configurations depends on numerous parameters, including porosity, orifice dimensions, mean and oscillating through flow and grazing flow levels, in addition to the overall geometry. In automotive applications, nonlinear orifice behavior may be expected. The present study applies a time domain fluid dynamic model to predict transmission loss of perforated tube elements. Since the Navier-Stokes equation is retained in nonlinear form, the technique shows promise for application to the breathing systems of firing engines, where numerous nonlinearities affect the validity of frequency domain analyses. Multiple-pass silencers with zero mean flow are modeled within an extended impedance tube configuration. The effects of overall geometry, porosity, and sound-pressure level are studied and limitations of the one-dimensional assumption are addressed. [Work supported by Ford Motor Co.]
Effect of moisture on flexural wave fundamental frequency of clamped-end cane reeds.
Authors: Chamuel Jacques R.
Published: October 2005

Experimental results are presented demonstrating the effect of moisture on the fundamental flexural wave frequency of clamped-end cane reeds. The flexural wave velocity decreases as the moisture level increases. The change in flexural wave velocity seems to be dominated by softening of the cane rather than by the added water mass. Plots are presented comparing the dependence of flexural wave fundamental frequency on moisture for different types of cane reeds. The results indicate that the fundamental frequency of a cane reed may decrease by as much as 30% as it becomes saturated with water. The flexural rigidity diminishes when the cane is moistened. The findings are important for the characterization and evaluation of reeds where hidden uncontrolled trapped moisture significantly affect the response, vibration, and stiffness of the reed.
Noise and hearing conservation regulations throughout the world.
Authors: Suter Alice H.
Published: October 2005

The advent of electronic communication enables professionals in noise and hearing conservation to communicate more effectively than ever before with their colleagues in other nations. This fact, added to the harmonization of noise standards by the European community, enables people to watch the development of trends throughout the world. The trend in nations’ noise standards is toward the 3-dB (equal-energy) rule, toward A-weighted permissible exposure limits below 90 dB, and toward more specific requirements for audiometric testing and the wearing of hearing protection devices. In addition to protecting workers against hearing loss, several nations include requirements to protect against other adverse effects of noise. Some nations have issued noise standards for specific workplaces, processes, and equipment. Enforcement of noise standards varies considerably among nations, with some nations viewing noise standards merely as recommendations, and others enforcing them seriously.
Various international approaches for evaluating impulse noise.
Authors: Johnson Daniel L.
Published: October 2005

For impulses with a peak sound-pressure level (SPL) under 140 dB, ISO1999 provides a standardized approach using total A-weighted energy. Some countries may use a small correction factor in addition. At the present time, most approaches for evaluating impulse noise above 140 dB use the peak sound-pressure level and some estimate of duration of the waveform. There is no recognized standard method for evaluating such impulses. Furthermore, the problem with this peak and duration method is that some waveforms with the same peak and duration parameters are far more hazardous than others. As will be discussed, each major country is using a slightly different approach. However, there is a NATO working group investigating a common approach. A part of this approach may be to use some type of weighted energy.
The audiometric phase of the hearing conservation program: Summary of activities from a global standpoint.
Authors: Royster Larry H. , Royster Julia Doswell
Published: October 2005

As part of the activities of ISO/TC 43/WG5: Evaluating the effectiveness of hearing conservation programs, a questionnaire was mailed out to the interested International Standards Organizations membership requesting information related to hearing conservation program activities. Part of this questionnaire dealt with the audiometric activities in each country. This paper will summarize the findings from this survey and discuss the past and present activities of ISO/TC 43/WG5. The significant differences that exist in the attitude toward obtaining and making use of audiometric data around the world will be discussed.
Remotely induced shear acoustic waves in tissues by radiation force of focused ultrasound.
Authors: Sarvazyan Armen P. , Rudenko Oleg V.
Published: October 2005

A new acoustic approach to medical imaging and diagnostics based on the remote evaluation of shear elasticity modulus of soft tissues is considered. The new method, called shear wave elasticity imaging, is based on the detection of shear waves remotely generated in tissues by radiation pressure of amplitude-modulated focused ultrasound. Remotely induced shear wave is fully attenuated within a short distance and the induced strain in the tissue can be extremely localized. By choosing appropriate temporal characteristics of the amplitude-modulated ultrasonic pulse, the volume of tissue involved in the mechanical excitation can be kept on the order of 1=A0 cm3, in contrast to other methods of elasticity imaging where the complete organ is subjected to shear stress. Consequently, evaluation of viscoelastic properties of tissue is greatly simplified since trivial boundary conditions can be assumed and an infinite medium model can be used to reconstruct the mechanical properties of tissue. Analytical equations describing the radiation force field induced by nonlinear focused ultrasound are derived and propagation of shear waves generated in tissues is considered. A possibility of deliberately exploiting the nonlinear effects to enhance the radiation pressure in a small area near the focus of the beam is shown.
Acceleration of thrombolysis by ultrasound in two rabbit models.
Authors: Francis Charles W. , Riggs Patrick N.
Published: October 2005

Ultrasound accelerates fibrinolysis in vitro at intensities that are potentially applicable clinically to enhance thrombolytic therapy. To extend these findings in vivo, the effects of ultrasound on fibrinolysis induced by streptokinase have been examined in two rabbit models. In a rabbit model of fibrinolysis in small vessels, scalpel cuts were made in the ear and rabbits were then rested 2 h to allow maturation of hemostatic plugs. Bleeding occurred when clots in small ear vessels were lysed during thrombolytic therapy. In a prospective study, administration of streptokinase alone results in bleeding after 18±3 min (mead ± SEM), but addition of ultrasound (1 MHz, 1 W cm−2 and a 50% duty cycle) shortened the time to bleeding to 7±4 min (p<0.05). The effect of ultrasound was also examined in a rabbit arterial thrombolysis model and, thrombolysis occurred in 9/17 (53%) of animals receiving both streptokinase and ultrasound, and this was significantly greater than the rate in animals receiving streptokinase alone (2/15, 13%, p=0.025). Light and electron microscopic examination revealed minor changes in platelet accumulation on the thrombus and minor changes in the vessel intima of ultrasound-exposed vessels. These findings indicate that externally applied ultrasound accelerates fibrinolysis in vivo.
Analysis and optimization of wedge transducers for Lamb wave excitation.
Authors: Degertekin F. Levent , Khuri-Yakub Butrus T.
Published: October 2005

Wedge transducers are commonly used to excite and detect Lamb waves in solid plates for NDE purposes. In this paper, the analysis and design of wedge transducers for efficient, single mode Lamb wave excitation in general multilayered anisotropic plates is presented. The incident acoustic field distribution on the surface of the plate due to a wedge transducer with arbitrary apodization is calculated using the angular spectrum method. Then, the particle velocity and stress field distributions in the plate in response to this source is obtained by the surface impedance approach. This field distribution can be expressed as a sum of Lamb wave modes in the structure, since the Lamb waves form an orthogonal mode basis. Once the mode amplitudes are found, the excitation efficiency for the desired Lamb wave mode is calculated. The results indicate a trade-off between efficiency and multimode excitation, as expected. To achieve both high efficiency and single mode excitation, an optimization scheme is used where the parameters involve the frequency of operation, dimension of the wedge, and the apodization function. The results of this analysis are presented for various practical examples.
Sound propagation in a periodically lined duct with a fluid flow.
Authors: Boij Susann , Nilsson Börje
Published: October 2005

Resonant lining is an effective measure to reduce tonal noise in ducts. It has been observed that a fluid flow in the duct can interact with the lining in such a way that sound is amplified. A model for the acoustic performance of an infinite duct with periodic lining (quarter wavelength resonators) and a nonzero mean velocity is developed. The fluid in the duct and lining are separated by an infinitely thin shear layer, the velocity in the duct is uniform, and the velocity in the lining is zero. Such a layer is unstable for all frequencies, a so-called Helmholtz’ instability. The linear acoustic equations are assumed to be valid. Based on the building block method, the acoustic modes in the periodic structure are calculated from the duct modes and scattering effects of the sharp edges. Numerical computations are done for a number of cases, where higher-order, evanescent, acoustic Floquet modes are omitted in order to simplify calculations. The direction of propagation of the computed modes is determined by the requirement of causality.
Ultrasonic velocity and attenuation of nano-scaled copper measured by laser ultrasonic technique.
Authors: Zhang Xiaorong , Gan Changming , Zhang Shiyi , Hauny Yuying , Xian Dingchang
Published: October 2005

The velocity and attenuation of an ultrasonic longitudinal wave for nano-scaled copper are determined by a laser ultrasonic technique. The nano-scaled copper samples are composed of super fine particles 10-nm in size, and are prepared by a suppressing and sintering technique under a vacuum, and different pressures are used in the experiment. These samples are of thicknesses between 125–300 μm. The experimental results show that the velocity dispersions and attenuation spectra of nano-scaled copper depend on their fabrication technology conditions, which are different from those of conventional Cu. The attenuation of nano-scaled copper is proportional to the frequency of ultrasound, and some absorption peaks appear at the curves of attenuation versus frequency, but the attenuation of conventional Cu is proportional to the square of the frequency. The velocity of nano-scaled copper is lower than that of conventional Cu. The experimental system, measurement method, results, analyses and discussions are also presented.
A nonlinear finite-element model of the vocal fold.
Authors: Lobo Arthur P. , O’Malley Michael
Published: October 2005

A large-displacement large-strain 3-D finite-element model of the vocal fold was developed. The structure is discretized into 720 elements with 3003 displacement and 720 pressure degrees of freedom. The model incorporates material and geometric nonlinearities. For the constitutive law, the Mooney–Rivlin rubber material formulation for an anisotropic hyperelastic material is used. Average incompressibility constraints are introduced by adding a hydrostatic pressure work term (Lagrange multiplier) to the strain energy density function. This term is a function of the bulk modulus which has the numerical equivalence of the penalty parameter. The nodal displacements and pressure are solved for independently, using a mixed displacement/pressure formulation with 8 displacement nodes (trilinear/hexahedron) and a constant (uniform) pressure term per element. Static condensation of the discontinuous pressure variable at the element level keeps the half-bandwidth of the stiffness matrix the same as for the displacement-only formulation. All nodes on the anterior commissure, vocal processes and the lateral surface (attached to the thyroid cartilage) are fixed-essential boundary conditions. An incremental-iterative strategy solves the dynamic equilibrium equations of motion in the total Lagrangian formulation. The vocal fold deformation was studied under a periodically time-varying pressure profile (natural boundary conditions) applied on 117 medial surface nodes.
Tongue control in speech: Some proposals tested on a biomechanical model.
Authors: Payan Yohan , Perrier Pascal
Published: October 2005

The ability of a 2-D biomechanical model of the tongue to reproduce kinematic properties of human tongue movements in V-V transitions is assessed. The model consists of a finite elements description, and simulates the main agonist/antagonist muscle pairs (posterior Genioglossus/Hyoglossus and anterior Genioglossus/Styloglossus). The external geometrical shape of the model has been adapted from X-ray data, to fit the tongue contours of a French native speaker. Movement data were collected on this speaker with an electromagnetometer (Carstens Electronics, AG100) for the tokens[i-a], [i-e], [i-ε], [a-i], [ε-i], [e-i], [i-e-ε-a], [a-ε-e-i], [y-œ], [y-o], [y-u], [u-y], [o-y], [œ-y], [y-œ-o-u], [u-o-œ-y]. For each token, the speaker was asked to keep the lip shape constant. The jaw was held in a constant position with a small bite-block (5 mm). For the simulations, according to Feldman’s equilibrium-point hypothesis [A. Feldman, ‘‘Once more Equilibrium-Point Hypothesis for motor control,’’ J. Motor Behav. 18 (1986)], movement was produced by shifting, at a constant rate, the mechanical equilibrium of the motor system from one equilibrium-target position to another one. Simulations are assessed in the kinematic and acoustic spaces. [Work supported by the European Union.]
Acoustic penetration of ocean sediments in the context of Biot’s theory.
Authors: Chotiros Nicholas P.
Published: October 2005

Acoustic penetration of ocean sediments will be examined in the light of the Biot–Stoll theory of sound propagation in porous media. This theory is attractive from a number of perspectives. From an applications point of view, it can account for a number of anomalies that have been observed experimentally but are not explainable in terms of the simpler viscoelastic wave propagation theory. From a theoretical perspective, it provides improved connections between the sediment geophysical properties, such as grain size, porosity, permeability, and frame moduli, and the acoustic properties, such as reflection loss, sound speeds, and attenuations. The difficulty in using Biot’s theory is mostly in the understanding and quantification of certain key input parameters, particularly the elastic moduli of the solid matrix, and of the constituent granular material. The potential reward is a unified theoretical frame work for research into ocean sediment acoustics that brings acoustics and geophysics closer together. [Work supported by ONR, Code 321 OA.]
A modification of Biot theory for unconsolidated sediment.
Authors: Nathwani K. Miguel , Henyey Frank S.
Published: October 2005

A mechanism for bottom penetration at low grazing angle is conversion of sound into Biot slow waves. Experiments in unconsolidated sediments have not found Biot slow waves with expected parameter values, but have found them in consolidated sediments. These results led us to consider a modification of Biot’s model for unconsolidated, sandy sediment. In our model, unstrained grains touch at a single point, since two adjacent grain surfaces have relative curvature. As the grains are pressed together, the contact area and the stress/strain ratio increase. Under extension the grains separate and there is no stress. The model predicts (lattice strain) ∝(stress)1/2 under compression. This scaling law should apply to any such medium, but the numerical coefficient depends on detailed properties of the lattice and grain geometry. Slow waves resulting from sound incident on the sediment are studied within the framework of this model. For simplicity, normal incidence is assumed. A positive effective lattice bulk modulus results from sediment overburden or from the pressure field of the sound. Numerical solutions and bounds on the production of slow waves in such a medium imply that the intensity of the slow wave is too low to have been observed by the experiments.
Echo-based neonatal breathing tube monitoring system.
Authors: Mansfield Jeffrey P. , Wodicka George R. , Shannon Daniel C.
Published: October 2005

A device to monitor the position and patency of neonatal breathing tubes (endotracheal tubes, ETT) was developed based on a pulse-echo technique originally employed in a system for adult breathing tubes [J. P. Mansfield and G. R. Wodicka, J. Sound Vib. 188(2), 167–188 (1995)]. A 100 μs duration sound pulse is emitted into the neonatal ETT via a wave tube containing a miniature sound source and a miniature microphone. The microphone detects echoes from acoustic impedance changes arising largely from changes in cross-sectional area within the ETT lumen and airways. The delays and amplitudes of echoes from obstructions within the ETT are used to estimate their respective locations and sizes. An echo arising from the ETT tip provides an estimate of the cross-sectional area just beyond the tube tip and is used to distinguish between proper tracheal and erroneous bronchial or esophageal intubations. Determination of tracheal position is accomplished by tracking the delay of a characteristic echo which arises from the airways. During intubation in five anesthetized rabbits, the device tracked changes in ETT position with an accuracy of 1±1.7 mm (mean±s.d.) over 188 measurements, which is adequate for use in even the smallest infant.
Spatial information in simultaneous multimicrophone recordings of thoracic sounds.
Authors: Kompis Martin , Wodicka George R.
Published: October 2005

An algorithm for the reconstruction of the distribution of sound sources within the thorax was developed. For any point within the thorax, the algorithm tests the hypothesis that it contains the only relevant source to explain a given set of simultaneous measurements on the chest wall. A hypothetical source signal is calculated by a least-squares estimation procedure for all points 1 cm apart on a equally spaced grid overlying the thoracic volume. The explained fraction of the total signal variance of all microphones is then displayed as a function of space in a 3-dimensional grey-scale coded image. The algorithm was applied to simultaneous lung sound recordings with eight microphones from two healthy male subjects. Preliminary findings suggest that inspiratory sounds are produced more peripherally in the thorax, while expiratory sounds originate more centrally. Some of the images depict features which correlate with anatomical structures such as the large airways, the heart, or during the process of swallowing, the esophagus. A mechanical lung model is being developed to investigate the significance and reproducibility of these images features. [Work supported by Swiss National Research Foundation, Roche Research Foundation, and NSF.]
Pitch perception of spectrally dense musical chords in a highly reverberant church.
Authors: Lindevald Ian M.
Published: October 2005

Pitch changes perceived across the transition from a driven room sound field to a freely decaying room sound field were studied in a subjective experiment. Spectrally dense organ chords were recorded in a church and later gated to provide samples from both the driven and the decaying sound fields. Terhardt’s dynamic pitch algorithm was used to analyze the chord samples for comparison with experimental results. On average, when choosing a lower octave sinusoid for tuning, subjects tuned flatter than when choosing a higher octave. This result is consistent with the predictions of Terhardt’s algorithm. Second, there was a consistent trend to perceive the reverberant sound field an average of about 20 cents flatter than the corresponding driven sound field. This effect is not predicted by Terhardt’s pitch model. [Work supported by the ASA’s Hunt postdoctoral fellowship of 1987–88.]
Design and measurements of variably nonuniform acoustic resonators.
Authors: Denardo Bruce , Bernard Miguel
Published: October 2005

The design, construction, and acoustical measurements of resonators with nonuniform cross-sectional areas that are easily altered to yield different resonance frequencies are described. These resonators are useful as educational demonstrations of symmetry breaking and of an effect of nonuniformity upon standing waves, and have been previously demonstrated and explained [B. Denardo, J. Acoust. Soc. Am. 95, 2935(A) (1994), and B. Denardo and S. Alkov, Am. J. Phys. 62, 315–321 (1994)]. Resonators that yield two, three, and four pitches are considered, where the relative frequencies are designed to correspond to musical intervals. Agreement is within 2% in all cases and 1% for most. The data reveal a breakdown of the theory, which is shown to be a result of additional kinetic energy, and thus effective inertia, near a discontinuity in cross-sectional area. The data also reveal that an appropriate end correction for this case is not that for a thin-walled tube but, rather, an infinite flange.
The Ohio State University Wind Ensemble.
Authors: Lewis Gary , Gardiner Kathleen
Published: October 2005

The Ohio State University Wind Ensemble musicians are the finest wind and percussion performers, both graduate and undergraduate, at the Ohio State University. These gifted young players will present an exciting program that displays their remarkable range of musical and dramatic capability. Youthful and dynamic, conductor Gary Lewis is in his premiere season as OSU director of bands. He comes to OSU from the University of Michigan, where he served as director of the Michigan Marching Band and as conductor of the Wind Ensemble and Contemporary Directions Ensemble. Professor Lewis is active as a guest conductor throughout the United States and is highly respected in the realm of both wind ensemble and orchestral conducting. Clarinet soloist Kathleen Gardiner, holds a prestigious Research and Graduate Council Fellowship and is a doctoral candidate at OSU. She was the first place winner of the International Clarinet Association solo competition in 1994 and the Eastman School of Music concerto competition in 1993. As a professional performer Ms. Gardiner serves as principal clarinet of the Pro Musica Chamber Orchestra.
Potential applications of acoustic generation of arterial microbubbles.
Authors: Carson P. L. , Fowlkes J. B. , Gardner E. A. , Bruce M. , Rubin J. M.
Published: October 2005

With intense, focused ultrasound pulses it is possible to generate microbubble boluses in the arterial system with potential diagnostic and therapeutic uses. Arterial microbubbles have been generated recently in flowing whole blood in vitro with 725 kHz ultrasound passing through canine tissues simulating human transcutaneous generation. Similar generation was reported previously [J. A. Ivey et al., Ultrasound Med. Biol. 21, 757–767 (1995)] from interoperative, in vivo exposures at 1.8 MHz and at higher intensities. If biological effects can be controlled acceptably, knowledge of ultrasonic bioeffects will be enhanced. Short boluses of ultrasonically imageable, less than 40 micron bubbles, generated in selected arteries, might be usable for diagnosis and monitoring of those macrovascular and perfusion abnormalities which currently are evaluated more slowly and, presumably, expensively. Very sparse distributions of 30 to 40 micron bubbles should provide point beacons with which to refocus ultrasound beams for high resolution imaging and treatment through aberrating tissues including the skull. Identification of feeder arteries to and disruption of flow to therapeutic targets should be achievable to enhance chemical or ultrasonic therapy. [Work supported in part by USPHS grant No. 2RO1 DK 42290 from the Nat’l Inst. Diab., Digestive and Kidney Disease.] a)Current address: Acuson, Inc., Mountain View, CA.
Intestinal hemorrhage from exposure to pulsed ultrasound and lithotripter fields.
Authors: Dalecki Diane , Child Sally Z. , Raeman Carol H. , Penney David P. , Carstensen Edwin L.
Published: October 2005

Using ultrasound with pulse lengths of 10 μs and pulse repetition frequencies of 100 Hz, the thresholds for intestinal hemorrhage in mice after a 5-min exposure range from ∼1 MPa at 1 MHz to ∼4 MPa at 4 MHz. With a piezoelectric lithotripter, the threshold for intestinal hemorrhage after 200 pulses was 1–3 MPa. In neither case can the effects be explained by heating. As a test for cavitation, the extent of hemorrhage in the gas-containing intestines of pregnant mice was compared to the amount of hemorrhage in the gas-free intestines of their fetuses. On the 18th day of gestation, the abdominal regions of pregnant mice (n=6) were exposed to 200 pulses from a piezoelectric lithotripter. Acoustic pulses had a peak pressure amplitude of 10 MPa and were administered at a rate of ∼1 Hz. All maternal intestines showed hemorrhagic regions extending several centimeters in length. In contrast, only 1 of 43 exposed fetuses showed an intestinal hemorrhage and this one lesion was less than one millimeter in diameter. These are consistent with a cavitation-related mechanism for the production of intestinal hemorrhage by exposure to acoustic fields.
Effects of ultrasound on function of the amphibian and the mammalian heart.
Authors: Dalecki Diane , MacRobbie Alan , Child Sally Z. , Raeman Carol H. , Carstensen Edwin L.
Published: October 2005

Exposure to the frog heart to single, millisecond length pulses of ultrasound has been shown to cause effects by two qualitatively different physical mechanisms. One of these effects has also been observed in mice. When the pulse is delivered during systole, it can cause a reduction in the developed aortic pressure. Evidence suggests that this arises from an action of radiation force on the heart tissues. The effect can be produced with an acoustic reflector over the heart. This maximizes the radiation force delivered to the heart, but eliminates direct interaction of the ultrasound with the heart tissue, thus experimentally eliminated heating and cavitation as mechanisms of action. When the pulse is delivered during diastole, it can produce a premature ventricular contraction. No premature ventricular contractions were observed with the acoustic reflector over the heart. The mechanism is nonthermal. Available evidence does not preclude cavitation as the primary physical mechanism responsible for premature ventricular contractions.
Acoustic properties of porous model media of spherical particles.
Authors: Tavossi H. , Tittmann B. R.
Published: October 2005

The through transmission method of longitudinal ultrasonic pulses was used to investigate the collective acoustic properties of a porous media model of cohesionless spherical particles. The results of this investigation showed dispersion and filtering effects for the transmitted acoustic waves. At low frequencies the wave velocity decreased with increase in frequency and particle size. In contrast at high frequencies the wave velocity decreased with increase in particle size, for relatively large particles (kR≫1). Calculated results from existing theoretical models for porous media by M. A. Biot, were compared to the experimental results. It was found that new modifications of the existing theoretical model for porous media were necessary in order to interpret the data in a quantitative manner.
Measurements of wind turbulence spectra near ground and implications for sound propagation calculation.
Authors: Stinson Michael R. , Daigle Gilles A. , Havelock David I.
Published: October 2005

Measurements of horizontal wind speed variations have been made at a local airfield using three different techniques and the resulting power spectra compared. The instruments used were a rotating three-cup anemometer, a sonic anemometer, and a hot-wire anemometer. The instrument sampling rates and frequency responses lead to upper frequency limits for the spectra of 0.5, 10, and at least 100 Hz, respectively. Good agreement was obtained between the techniques for those frequencies where they overlap. Knowledge of the shape of the turbulence spectrum is necessary for the incorporation of turbulence scattering into outdoor sound propagation calculations. The observed spectra tend to vary with frequency f as f−5/3 over the range 0.001 to 100 Hz (corresponding to turbulence length scales between 5000 and 0.05 m, for a mean wind speed of 5 m/s) although there are significant deviations from this simple dependence. The observed results are consistent with the analysis of Ho/jstrup [J. Atmos. Sci. 39, 2239–2248 (1982)].
A theory of the principal monaural pathway. II. Rhythm, streaming, and comodulation masking release.
Authors: McAngus Todd Neil P.
Published: October 2005

The model [N. Todd, ‘‘A theory of the principal monaural pathway. I. Pitch and time perception,’’ J. Acoust. Soc. Am. (these proceedings)] proposes to account for auditory streaming by a cross-correlation mechanism modeled as an array of cortical columns. A column contains excilatory and inhibitory interneurons and pyramidal cells which receive input from both the thalamus and from neighboring columns. For columns with coherent thalamic inputs, the outputs of the pyramids sum across frequency because local interneurons compute a correlation between the AM transform of the inputs of the local and remote columns, and selectively gate the input to the pyramidal cell. (1) Grouping by frequency proximity—for columns separated by less than a critical band, thalamic inputs are unresolved. (2) Grouping by temporal proximity—at repetition rates below the mean of the AM distribution, AM fundamentals are less well represented; at higher repetition rates the AM harmonics are more separated. (3) Temporal development—where the AM spectra take time to develop. The AM coherence mechanism also gates the inputs to disjoint subpopulations of a low-pass mechanism, and thus also accounts for comodulation masking release, since backward masking will only take place within a single subpopulation.
The need for efficient monitoring of data.
Authors: Corliss Edith L. R.
Published: October 2005

‘‘Shirtsleeve Statistics’’ is a name that has been applied to simplified methods for inspecting statistical properties of experimental data. Many of these techniques are in the nature of ‘‘nonparametric’’ statistical operations. Because of their simplicity, they are particularly valuable for monitoring the results of an experiment in progress. Also, study of the inherent relations of the variables can make for a more efficient layout of an experimental procedure. One vital result of this study of observations and their uncertainties is the elucidation of the quantity N, the number of independent variables involved in an experiment. Merely counting the number of observations does not suffice. Internal correlations can affect the degree of independence of the observations and thus exaggerate their estimated precision. Techniques are available for simple and timely monitoring of measurement consistencies. It is exceedingly important to keep a running statistical surveillance of data. Inherent variations in the phenomena being measured may obscure temporarily a failure in the measuring or data reduction equipment. Much time and data can be lost. (Remember: Dust swept under the rug raises a lump.)
A method for analyzing rating scale data.
Authors: Levitt Harry
Published: October 2005

Subjective ratings are often used in the evaluation of hearing aids, loudspeakers, speech processors, and other systems involving sensory stimuli. The analysis of rating data, however, presents problems since the usual parametric assumptions underlying standard statistical techniques (e.g., t tests, analysis of variance) are not applicable to subjective ratings. A nonparametric method of analyzing rating data is described using concepts derived from signal detection theory. In order to compare two sets of ratings, a nonparametric estimate of the area under the ROC curve is obtained by first deriving the correlation function relating the two sets of ratings and then summing over half the range of the correlation function. This statistic, the half summed correlation (HSC), is relatively easy to compute and can be used to test, with known statistical power, for various differences between two sets of ratings (mean differences, variance differences, mean plus variance differences). It is also possible to rank sets of ratings using this statistic and to apply various multidimensional techniques designed for ordinal data. A variation of the analysis of proximities using HSC’s will also be described. [Work supported by NIDCD.]
Analysis of induced chaos in Duffing’s equation, using Caseygrams.
Authors: Vaidya P. G. , Winkel C. R.
Published: October 2005

In speech signals, a newer type of chaos has been observed. It could be termed as an ‘‘induced chaos.’’ In order to see if this type of chaos can be stimulated, in a theoretical setting, the Duffing’s equation has been looked at. The parameters of this equation have been chosen in such a way that this would result in an output which is normally nonchaotic. However, the driving amplitude has been modulated, and in turn, the phase and the driving frequency. All of these led to ‘‘induced chaos.’’ This chaos differs in certain important characteristics from the usual chaos. It was found that the best way to detect such a chaos was to use the differential trans-spectrograms, or the ‘‘Caseygrams.’’ These are obtained by calculating the difference between two specific types of trans-spectral coherences, (TSC’s) [P. G. Vaidya and M. J. Anderson, J. Acoust. Soc. Am. 89, 2370–2378 (1991)]. These two TSC’s are specifically developed to measure the interaction of the main harmonics with the subharmonics. These results show that as the modulations increased the induced chaos became more and more apparent in terms of the difference between the TSC’s, and thus in the Caseygram. A theoretical explanation of these results is included.
Wideband higher-order spatial processing of active sonar echoes.
Authors: Dwyer Roger F.
Published: October 2005

When linear sonar arrays are operated well beyond their design frequency, spatial resolution is reduced at low frequencies and grating lobes appear at higher frequencies based on the second-order spectrum. Because the higher-order spectrum provides more flexibility in choosing the frequency response at the output of a beamformer, the deliterious effects of wide bandwidths can be reduced. This will be demonstrated with active sonar waveforms returned from spherical targets.
Model reference signal processing for a laser ultrasonics experiment.
Authors: Candy James V. , Thomas Graham H. , Chinn Diane , Spicer James B.
Published: October 2005

Laser ultrasonics is an exciting optical methodology of nondestructive evaluation offering a means of detecting flaws in materials especially in hostile areas where contact transducers cannot function such as high temperature environments or awkward areas where the laser is easily directed by mirrors for rapid scanning and measurement. Typical measurement techniques utilize laser interferometers to accurately measure surface displacements. In this paper the feasibility of applying model-reference signal processing techniques are investigated that would improve the performance of a moderate cost, Michelson interferometric measurement system. A model-reference approach is developed to solve the signal enhancement problem for a laser ultrasonics application in nondestructive evaluation. In this problem a sophisticated laser thermoelastic propagation model is used to predict the surface displacement of the specimen under test. Once synthesized, this model displacement response is used as the reference signal in an optimal (minimum error variance) signal enhancement scheme. Both fixed and adaptive processors are considered in this application where it is shown that a significant improvement in signal levels can be achieved over the usual methods to enhance noisy data acquired from a Michelson interferometric measurement system and increase its overall sensitivity.
Acoustic-optic hybrid imaging experiment.
Authors: Matthews Anthony D. , Arrieta Lisa L.
Published: October 2005

A series of experiments to determine the ability of laser vibrometers to receive and process echoes from the water surface are described. Imaging of the bottom and objects lying on the bottom is attempted. The excitation is accomplished by a submerged acoustic source operating near 10 kHz. The degradation of the image is quantified as a function of wave height. Experiment results are reported. [Work supported by Coastal Systems Station under Internal Research funding.]
Measurement and localization of interface wave reflections from buried objects.
Authors: Smith Eric , Wilson Preston S. , Bacon Fred W. , Manning Jason F. , Behrens John A. , Muir Thomas G.
Published: October 2005

It is demonstrated that interface wave reflections from buried objects can be created with an active seismic interface wave sonar, and measured and localized on a seismic array. The sonar reported here was implemented on a natural beach of the Gulf of Mexico. It employs a monostatic source/receiver geometry with a three-element horizontal receiving array, in which each element is a triaxial geophone (velocimeter). Detailed measurements of propagation loss at the site make it possible to compare reflected signal power with the results of predictions computed in first order, pointlike-scatterer perturbation theory. These propagation measurements, together with phase information, verify that the reflections are interface waves, and measured values agree well with predictions, within experimental and theoretical errors, both of which are well constrained and small. Simulated data are used to compare a beam pattern at uniform shading with experimental results, and it is found that nonuniform shading in the experimental data produces closest correspondence. Independently performed ground truthing and reverberation analysis further provide a consistent and thorough picture of the background sound fields from which these echos must be extracted. [Work supported by the Office of Naval Research.]
Modes of vibration and directivity of percussion instruments.
Authors: Rossing Thomas D.
Published: October 2005

Musical instruments in the percussion family radiate sound from many normal modes of vibration. These modes have distinctly different radiation patterns, resulting in a sound field that varies markedly with frequency and with time. Some of the modes of vibration and the resulting radiation patterns obtained from a representative number of percussion instruments, including bells, various types of drums, and cymbals, are described.
Sound intensity patterns from two bass handbells.
Authors: Mansell Edward R. , Rossing Thomas D.
Published: October 2005

The sound intensity patterns of two G1 handbells were investigated. One bell is aluminum and the other is traditional bronze. The results indicate that the aluminum bell has a better radiation efficiency for the (2,0) mode fundamental (f=49 Hz). Sound intensity was mapped for the two tuned modes of vibration: the (2,0) and (3,0) modes. The parametric radiation (twice the mode frequency) was significant for both modes, especially the (3,0). The measurement of both active and reactive sound intensity reveals a better picture of the sound field than sound pressure alone. Both of the bells are poor radiators of the fundamental because of their small dimensions compared to the sound wavelength in air. [Both bells on loan from Malmark, Inc.]
Talker direction finder system implemented with cardioid beams and DSP algorithm.
Authors: Baumbauer John C. , Michel Alan D. , McAteer Jeffrey P.
Published: October 2005

A prototype talker direction finder (TDF) algorithm has been developed that will rapidly locate a new talker (within 200–400 ms) or track a moving one. For most room configurations, the algorithm has an inaccuracy mean of less than 10° of azimuthal angle and a standard deviation of 7°. The TDF provides full room, 360° coverage. A prototype where the TDF physically rotates a camera toward the talker has demonstrated the TDF’s robustness in difficult (i.e., realistic) noisy and reverberant environments. The physical inputs to the TDF are three small and inexpensive omnidirectional microphone elements that are all placed within a 1-in. circle, allowing inconspicuous design into a consumer product. Three μ-law codecs provide Inputs to the digital signal processor where the TDF’s new least-mean-squares-type adaptive algorithm resides. The overall system design is summarized, including preprocessing to reduce the effects of noise and reverberation. The adaptive algorithm, which employs redundant ‘‘pattern matching’’ to six cardioid acoustic pickup beams formed from the three microphone element inputs, is then presented. The TDF can provide enhanced solutions for teleconferencing and speakerphone acoustic systems. The algorithm could be used to provide directional information to steer an ‘‘adaptive beamformer’’ for advanced audio pickup applications.