bluuebunny/crossref_metadata_2025 huggingface dataset:
Recollections of studies in the laboratory of A. H. Benade: 1975–1978
Authors: Thompson Stephen C.
Published: October 2005

From 1975 to 1978 the author had the honor of studying acoustics as a graduate student in the laboratory of Professor A. H. Benade. By this time, much of the fundamental work in understanding the physics of wind instrument air columns, tone holes, and the nonlinear interaction between the air column and its excitation mechanism had been developed. Fundamentals of Musical Acoustics had just been sent to the publisher. Questions concerning some of the more subtle aspects of wind instrument behavior were beginning to be asked: reed resonance effects, spectral transformations from the instrument to the room, mutual interaction of the radiation from adjacent tone holes, and the modification of air column resonances by the player's airway impedance. And all of the new physical understanding was routinely being converted to the musical instrument craftsman's intuitive methods for improving the playing behavior of instruments. For Art, the theoretical understanding of physical phenomena and the practical application of these new ideas in the “real world” of the musician held equal status. This constant interplay of theory, experiment, and practical application created a chain reaction of ideas which is still underway. This paper will recount the author's recollections of the atmosphere and developments of that time period.
Woodwind design algorithms to achieve desired tuning
Authors: Keefe Douglas H.
Published: October 2005

Techniques exist to analyze woodwinds of known geometry. The inverse problem is a technique by synthesis which determines tone hole placements to approximate ideal tuning for tones the instrument is intended to produce. Two algorithms using a relaxation technique have as inputs: mouthpiece equivalent length, bore shape, tone hole dimensions, and mode number. Outputs include the tone hole positions, deviation from harmonic alignment of modal resonances, and open hole lattice cutoff frequencies. Bad designs are detected, forcing the designer to modify the bore or tone hole geometry. The first algorithm, due to Benade, uses a model based upon regular, semiinfinite tone hole lattices, and he employed it in designing the NX clarinet and other woodwinds. The new algorithm incorporates damping, a general tone hole model, lattice irregularities and finite bell termination. The algorithm allows calculation of input impedance and reflection functions for subsequent time domain simulations. The playing behavior of flutes constructed using these algorithms correlates well with predictions. Comparisons of the algorithms and their sensitivity to variations in tone hole impedance models will be discussed.
A. H. Benade and the perception of music
Authors: Lindevald Ian M.
Published: October 2005

Benade's fascination with the great skill by which the auditory system understands the complicated signals supplied to it grew from his primary interest in the physics of musical instruments. Often, solutions to problems of physics would force questions of perception. The link between physics and perception was natural for him, rounding out his knowledge of musical instruments as sound sources and the concert hall as a transmission system with serious inquiry regarding the auditory system as the sound's receiver. Benade's work in musical perception was guided by his devotion to “real world” acoustics and reflected his commitment to approaching his science from the viewpoint of those most affected by music, the musicians and experienced listeners. The author, who was Benade's last degree-earning doctoral student, will discuss the work in music perception: from the coffee room queries, through the formal research, and, finally, on to the continuing efforts to answer the questions that Benade left, so that we too may have some fun. [Work supported by the ASA's F. V. Hunt Postdoctoral Fellowship.]
Use of sound intensity for determination of air-moving device noise emission
Authors: Balant A. C. , Maling George C.
Published: October 2005

American National Standards on sound power determination via sound intensity and on measurement of noise from air-moving devices are at an advanced stage of development. The latter proposed standard requires a special test facility such as a reverberation room or a hemi-anechoic room, and does not permit the use of sound intensity for determination of noise emission. In this paper, the results of sound power determinations on air-moving devices in a reverberation room, a hemi-anechoic room, and in an ordinary laboratory environment are presented. The data in the ordinary room were obtained using sound intensity methods. The accuracy of the data in all three environments is discussed. Many of the “field indicators” which are recommended in the proposed sound intensity standard have been calculated in order to determine acceptable ranges for these indicators. The results indicate that determination of air-moving device sound power in ordinary rooms is adequate for many engineering purposes. Use of sound intensity for determination of air-moving device sound power should increase the amount of data available on these sources.
A variational principle for the scattered wave
Authors: Freund D. E. , Farrell R. A.
Published: October 2005

Schwinger-type variational principles are presented for the scattered wave in the case of scalar wave scattering for an arbitrary incident field from an object of arbitrary shape with either homogeneous Dirichlet or homogeneous Neumann boundary conditions. Designating the distance from the scatterer to the observer by r, then the results are variationally invariant for all values of r ranging from the surface of the scatterer to the farfield. Explicit results are presented for the case when the scatterer is a sphere obeying homogeneous Dirichlet boundary conditions. Special attention is given to the selection of the trial fields that produce accurate results over a broad frequency range. [Work supported by the U.S. Navy.]
An analysis of partial wave scattering coefficients and the interpretation of resonances and background in scattering from elastic targets
Authors: Werby M. F. , Überall H.
Published: October 2005

Bistatic angular distributions and backscattered form functions can be, represented as a partial wave series where the angular contribution can be. written in terms of spherical harmonics or some other suitable angular function. It is possible to represent elastic, rigid, and solid targets in such a representation. The appropriate background (in partial wave space) can be subtracted from some elastic target and a resonance can be isolated. This is usually done by assuming a rigid or a soft background for elastic: solids or thin shells and leads to a residual response that, under appropriate conditions, can manifest a resonance. Often, however, neither a rigid nor a soft background is suitable. This can be established by examining the residual partial wave coefficients, which, in the event of a poor choice of background, will lead to a mix of several partial waves at resonance. On the other hand, for a good background choice, a predictable mix of partial wave coefficients will be observed. When a suitable background has been chosen, then the partial wave analysis allows one to characterize the resonance.
GTD for backscattering from elastic objects in water: Phase of the coupling coefficient and a simplified synthesis of the form function
Authors: Marston P. L. , Williams K. L.
Published: October 2005

The geometrical theory of diffraction (GTD) was recently extended to describe surface elastic wave (SEW) contributions to scattering from fluid-loaded spheres and cylinders at high frequencies [P. L. Marston, J. Acoust. Soc. Am. 83, 25–37 (1988)]. The coupling of an SEW with the scattered field was described by a complex coefficient G. That analysis gave simple physical approximations: |G| ≈ 8πβc/cSW for spheres and |G| ≈ 8πβ/(π ka)1/2 for cylinders. The SEW angular attenuation coefficient (due to radiation damping) and phase velocity are β and cSW, while c denotes the sound speed in the fluid, k = ω/c, and a is the object's radius. The present work gives approximations for the phase of G derived in the limit β ≪ 1 by assuming that SEW contributions match those of resonance scattering theory based on a rigid background. The resulting phase of G is ≈ 0 for solid spheres and ≈ π/4 for solid cylinders. The resulting approximation for spheres G ≈ 8πβc/cSW yields a synthesis of the exact form function similar in quality to previous ones [K. L. Williams and P. L. Marston, J. Acoust. Soc. Am. 79, 1702–1708 (1986)] based on direct numerical evaluations of G. The results suggest that, given β and cSW > c, the SEW contribution may be accurately approximated when ka ≫ 1. The new synthesis used a simple approximation for the specular contribution. [P. L. Marston was supported by ONR.]
Identification of whispering gallery type waves on a finite cylindrical shell using MIIR
Authors: Numrich S. K. , Maze G. , Izbicki J. L. , Ripoche J.
Published: October 2005

Experiments were conducted at Laboratoire d'Electronique et d'Automatique (ULTRASONS) to confirm the presence of whispering gallery type waves on a finite cylindrical shell bounded by hemispherical endcaps. The method of isolation and identification of resonances (MIIR) developed by the research team at ULTRASONS was used to obtain the histatic mode patterns that conclusively identified the modes observed monostatically by researchers at the Naval Research Laboratory. The radiation patterns for the several low-order whispering gallery modes were identifiable when the cylindrical shell was insonified normal to its major axis. Unequivocal identification of higher-order modes was inhibited by the presence of waves traveling along other circumferential paths.
Acoustic scattering from large-aspect ratio, axisymmetric shells: II
Authors: Hackman Roger H. , Todoriff Douglas G.
Published: October 2005

Previously [R. H. Hackman and D. G. Todoroff, J. Acoust. Soc. Am. Suppl. 1 82, S49 (1987)], a comparison was presented of the predictions of the spheroidal-coordinate based T matrix with preliminary measurements of the acoustic scattering from a copper, prolate spheroidal shell at axial incidence. This target had an aspect ratio of L/D = 7 and a constant thickness of 5% of the semiminor axis. Here, more detailed measurements are presented and both the calculations and the measurements to general incidence are extended. The emphasis of this work is the physical analysis of the elastic excitations of the scatterer. The predictions of the spheroidal-coordinate based T matrix are also compared with previously published spherical-coordinate based T-matrix calculations for thin axisymmetric shells.
Multiple scattering analysis for a target in an oceanic waveguide
Authors: Hackman Roger H. , Sammelmann Gary S.
Published: October 2005

A multiple scattering analysis is presented for a target in a range-independent oceanic waveguide. The multiple scattering series is explicitly summed and a solution is obtained in closed form. The solution agrees with that presented earlier [R. H. Hackman and G. S. Sammelmann, J. Acoust. Soc. Am. 80, 1447–1458 (1986)] for all cases that were checked. The method provides an attractive alternative to the previous formalism in two regards. First, this approach provides insight into the algebraic structure of the solution. The individual terms in the final solution may be simply interpreted in terms of single scattering processes. And, second, there is less algebra involved when relatively simple waveguides are considered. Numerical examples are given that illustrate the importance of contributions involving rescattering among the target and the waveguide boundaries.
Bounded beam transmission across water/sand interface. Part II—Experiment versus theory
Authors: Williams K. L. , Satkowiak L. J.
Published: October 2005

The experiments described in the previous presentation allow the generation of contour plots of the pressure field within the sediment for different types of sending transducers at several grazing angles (defined here as the angle between the interface and central axis of the sender). These contour plots are compared with theoretical predictions calculated using the SAFARI model [H. Schmidt and F. B. Jensen, J. Acoust. Soc. Am. 77, 813–825 (1985)]. Results indicate that the shear degree of freedom in the sediment is unimportant under the conditions of the experiment. Agreement between SAFARI and experimental pressure field contours is good for all senders used in the experiment. This suggests that nonlinear effects due to parametric array truncation were not readily apparent in the contour plots. Based on the experimentally determined in-sediment direction of propagation, the presence or absence of beam displacement for each type of acoustic source will be discussed.
Computations of rigid body scattering by long, slender finite cylinders using the T-matrix method
Authors: Sarkissian Angie
Published: October 2005

Waterman's T-matrix algorithm requires the evaluation of matrix elements Qlk whose imaginary parts are difficult to evaluate for l<k for long, slender scatterers, at high frequencies, because they involve surface integrals of large oscillatory functions. Machine precision required for numerical integration of these matrix elements increases as the frequency is increased. Therefore, the frequency range over which the method can be applied is usually limited by the precision of the computer used. Certain shapes, such as ellipsoids, have symmetric Q matrices; since numerical integration of the difficult side of the matrix can be avoided for these shapes, the frequency range over which the method can be applied seems to be limited by machine memory alone. A different approach for the evaluation of the imaginary part of Q will be shown for finite cylinders where the antisymmetric part of the matrix is written in a form involving surface integrals that are more easily computed. By avoiding integration of large oscillatory functions, this method overcomes the difficulties associated with long slender cylinders and enables high-frequency computations. [Work supported by Naval Research Laboratory, Washington, DC.]
Coupling between ear canal and eardrum in model systems
Authors: Stinson Michael R. , Khanna Shyam M.
Published: October 2005

This paper examines a theoretical model of sound propagation in the ear canal that accounts for the distributed acoustical load presented by the eardrum. This model is an extension of our previous one-dimensional formulation [S. M. Khanna and M. R. Stinson, J. Acoust. Soc. Am. 77, 577–589 (1985)], which was limited to rigid-walled canals. The spatially varying motion of the eardrum enters as a driving term in the equation for the sound field. In principle, this present model can be combined with detailed, dynamical models of the tympanic membrane. Experiments using model canals are underway to test the theory. In these, the sound field is determined with the eardrum replaced by either a mechanically driven piston or a passive, locally reacting load. Preliminary results indicate that the theoretical formulation can describe the sound field in the cat ear canal up to at least 25 kHz and in the human ear canal up to at least 15 kHz.
Distribution of two major organ of Corti proteins in different component cell types
Authors: Kraus Peter , Varghese Jogy , Thalmann Isolde , Thalmann Ruediger , Zenner H.-P.
Published: October 2005

Two highly acidic, low molecular weight proteins, present in very high concentration in the organ of Corti (OC) and termed OCP-I and OCP-II [I. Thalmann et al., Arch. Otorhinolaryngol. 226, 123–128 (1980)] have been previously described. The proteins do not contain significant amounts of carbohydrate and are soluble in both high- and low-ionic strength buffer. The distribution of these unidentified proteins in different cell types of the OC has now been determined and has been compared with the distribution of actin, tubulin, and calmodulin. Freeze-dried and freshly dissected substructures of the OC of chinchilla and guinea pig were used, respectively. Actin was found to be particularly abundant in the inner and outer pillar cells. In the Hensen and Deiters cells, OCP-I and OCP-II predominate and calmodulin is present only in very small quantities. In contrast, the outer hair cells exhibit a strong accumulation of calmodulin, with relatively low levels of OCP-I and OCP-II, actin and tubulin. In the neuroepithelium of the sacculus OCP-I and OCP-II are present at about 40 times lower concentrations than in the OC.
The Poynting vector and source identification for thin plates and shells
Authors: Williams Earl G. , Abraham Phillip B. , Romano Anthony J.
Published: October 2005

The Poynting vector I, well known in the three-dimensional theory of elasticity, represents the three-dimensional power flow in a solid. It is shown how I can be used to derive the power flow in a thin flat plate, and a thin cylindrical shell. The divergence of I provides the rate of change of total energy density (the Hamiltonian density,∂H/∂t) in the shell. Its time average must vanish for steady-state conditions. This leads to the conclusion that power flow in and out of the structure is given by Π = ∮〈I2D〉t n̂ dl, a line integral (over the shell surface) of the in-plane, average intensity in the shell. If the shell is point driven, then Π is large at that point, and can be used to locate the position and strength of the mechanical source. This provides an excellent tool for mechanical source identification. These concepts will be demonstrated and verified using synthetic and real data on point driven cylindrical shells in water. In the synthetic data, the full displacement vector (u,v,w) is specified throughout the shell. In the real data, measurements of the radial component (w) of shell motion are used. In the latter case (only w known), it will be shown how it is possible, however, to get a good estimate of Π, and thus locate the mechanical source.
Response of a van der Pol oscillator to modulated sinusoidal input
Authors: Davies Huw G. , Nandlall Dennis
Published: October 2005

The response of a van der Pol oscillator with nonlinear damping and an external periodically modulated sinusoidal input is analyzed by using the method of multiple time scales. The modulation appears to provide extended stability. At resonance, the response envelope is highly nonlinear. Away from resonance the modulation causes a periodic switching on and off of a natural frequency limit cycle superimposed on the excitation frequency response. The natural frequency component arises through a parametric excitation. Extensive numerical simulations confirm the analytic results. Stability studies and the application to random modulations are also discussed: [Work supported by NSERC Canada.]
The role of duration in the perception of consonants within reduced syllables
Authors: Archambault Danièle
Published: October 2005

The role of duration as a perceptual cue to the presence of two underlying consonants versus one is examined in Montreal French. Due to deletion of the intervening phonetic segments, two identical syllable-initial consonants may be joined in one articulation such that, for example, two plosives show a single burst. A series of utterances in which these double consonants and the corresponding single ones appear in identical segmental contexts were recorded and then presented to listeners in perceptual tests (e.g., la plupart (most of it)→/laplypar/→[lap:ar] as opposed to la part (the part)→/lapar/→ [lapar]). To insure that listeners base their judgment on duration to distinguish between the utterances, they were also presented with the same sentences in which, by use of signal processing, the durations of the consonants were inverted, i.e., the double consonant was given the relative duration of the single consonant and vice versa. Results show that while a long duration consistently leads listeners to recognize a double consonant, a short duration does not automatically prompt them to identify a single consonant. Results also indicate that consonant duration must be considered in a context larger than that of the syllable. [Research done at the Université de Montréal and supported by National Research Council of Canada and Québec Government.]
Differences in human and monkey sensitivity to acoustic cues underlying voicing contrasts
Authors: Sinnott Joan M. , Adams Frank S.
Published: October 2005

Humans and monkeys were compared in their differential sensitivity to various acoustic cues underlying voicing contrasts specified by voice-onset time (VOT) in utterance-initial stop consonants. A low-uncertainty repeating standard AX procedure and positive-reinforcement operant conditioning techniques were used to measure difference limens (DLs) along a VOT continuum from −70 ms (prevoiced /ba/) to 0 ms (/ba/) to +70 ms (/pa/). For all contrasts tested, human sensitivity was more acute than that of monkeys. For voicing lag, which spans a phonemic contrast in English, human DLs for a /ba/(standard)-to-/pa/(target) continuum averaged 8.3 ms compared to 17 ms for monkeys. Human DLs for a /pa/-to-/ba/ continuum averaged 11 ms compared to 25 ms for monkeys. Larger species differences occurred for voicing lead, which is phonemically nondistinctive in English. Human DLs for a /ba/-to-prevoiced/ba/ continuum averaged 8.2 ms and were four times lower than monkeys (35 ms). Monkeys did not reliably discriminate prevoiced /ba/-to-/ba/, whereas humans DLs averaged 18 ms. The effects of eliminating cues in the English VOT contrasts were also examined. Removal of the aspiration noise in /pa/ greatly increased the DLs and reaction times for both humans and monkeys, but straightening out the F1 transition in /ba/ had only minor effects. Results suggest that quantitative differences in sensitivity should be considered when using monkeys to model the psychoacoustic level of human speech perception.
Consonant reception in noise by listeners with mild and moderate sensorineural hearing impairment
Authors: Zurek P. M. , Delhorne L. A.
Published: October 2005

The goal of this study was to determine the extent to which the difficulty experienced by impaired listeners in understanding noisy speech can be explained on the basis of elevated tone-detection thresholds. Twenty-one impaired ears of 15 subjects, spanning a variety of audiometric configurations with average hearing losses to 75 dB, were tested for reception of consonants in a speech-spectrum noise. Speech level, noise level, and frequency-gain characteristic were varied to generate a range of listening conditions. Results for impaired listeners were compared to those of normal-hearing listeners tested under the same conditions with extra noise added to approximate the impaired listeners’ detection thresholds. Results for impaired and normal listeners were also compared on the basis of articulation indices. Consonant recognition by this sample of impaired listeners was generally comparable to that of normal-hearing listeners with similar threshold shifts listening under the same conditions. When listening conditions were equated for articulation index, there was no clear dependence of consonant recognition on average hearing loss. Assuming that the primary consequence of the threshold simulation in normals is loss of audibility (as opposed to suprathreshold discrimination or resolution deficits), it is concluded that the primary source of difficulty in listening in noise for listeners with moderate or milder hearing impairments, aside from the noise itself, is the loss of audibility.
A pulse ribbon model of monaural phase perception
Authors: Patterson Roy D.
Published: October 2005

This article presents two sets of experiments concerning the ability to discriminate changes in the phase spectra of wideband periodic sounds. In the first set, a series of local phase changes is used to modify the envelopes of the waves appearing at the outputs of a range of auditory filters. The size of the local phase change required for discrimination is shown to be strongly dependent on the repetition rate, intensity, and spectral location of the signal. In the second set of experiments, a global phase change is used to produce a progressive phase shift between the outputs of successive auditory filters, without changing the envelopes of the filtered waves. Contrary to what is often assumed, listeners can discriminate between-channel phase shifts once the total time delay across the channels containing the signal reaches 4–5 ms. In this case, however, the discrimination is largely independent of signal parameters other than bandwidth. A highly simplified model of the cochlea, consisting of an auditory filter bank and units that record the times of the larger peaks in the filter outputs, is developed to explain the two contrasting sets of results.
Perception of amplitude and frequency modulated signals (mixed modulation)
Authors: Ozimek Edward , Sȩk Aleksander
Published: October 2005

This article discusses the detection of mixed modulation, i.e., simultaneous amplitude and frequency modulation (MM). The investigations have incorporated both a sine wave modulating signal and an irregular modulating signal, a very narrow noise band, of a specified center frequency. The results revealed that for a sinusoidal low-frequency modulating signal, amplitude and frequency changes that were separately subthreshold could be detected by listeners in mixed modulation. This indicates summation of sensations caused by simultaneous AM and FM modulation. This effect was not observed in the case of the irregular modulating signal. A hypothesis is advanced that the perception of modulated signals is governed by two mechanisms, viz., temporal and spectral. The operation of the two mechanisms depends mainly on the modulating frequency. The type of modulation does not play any significant role in this case.
Changes in head position as a measure of auditory localization performance: Auditory psychomotor coordination under monaural and binaural listening conditions
Authors: Perrott David R. , Ambarsoom Hamlet , Tucker Julianna
Published: October 2005

Two experiments examined the capacity of listeners to turn and face an active sound source. Tests were conducted with sources located in the subject’s forward field (an arc extending from 60° to the subject’s right to 60° to the left). Localization performance was determined under both monaural and binaural listening conditions, using both brief pulses and sustained pulse trains as target signals. Not unexpectedly, the ability to orient the face to a hidden sound source was very poor under monaural conditions if the listener received only a brief (100-ms) tonal pulse. When continuous pulse trains were employed, localization, even under monaural conditions, became quite accurate. Across conditions, this complex motor response produced results in agreement with those that have been obtained when subjects were only required to report their spatial impressions. In particular, performance with binaural pulse trains was observed to vary as a function of the frequency of the target signals employed. Descriptions of the head movement response, along with a discussion of some of the implications of ear–head coordination, are presented.
Numerical methods for solving one-dimensional cochlear models in the time domain
Authors: Diependaal Rob J. , Duifhuis H. , Hoogstraten H. W. , Viergever Max A.
Published: October 2005

In this article, a robust numerical solution method for one-dimensional (1-D) cochlear models in the time domain is presented. The method has been designed particularly for models with a cochlear partition having nonlinear and active mechanical properties. The model equations are discretized with respect to the spatial variable by means of the principle of Galerkin to yield a system of ordinary differential equations in the time variable. To solve this system, several numerical integration methods concerning stability and computational performance are compared. The selected algorithm is based on a variable step size fourth-order Runge–Kutta scheme; it is shown to be both more stable and much more efficient than previously published numerical solution techniques.
Nonlinear magnetoacoustic equations
Authors: Abd-Alla Abo-el-Nour , Maugin Gérard A.
Published: October 2005

The present work sets forth in a rotationally invariant form the basic equations of nonlinear magnetoacoustics. Presented in the quasimagnetostatic approximation, these equations are useful to treat both bulk and surface nonlinear wave-propagation phenomena in centrosymmetric magnetostrictive materials (such as ferromagnetic polycrystalline materials, which can be used in the conception of electromagnetic-acoustic transducers, so-called EMATS). The equations obtained are based on a strict use of nonlinear continuum mechanics and the electrodynamics of continua with magnetomechanical interactions. All equations are given a material (invariant) form that proves to be most convenient in the study of nonlinear problems in anisotropic bodies.
Performance of the parametric receiving array: Effects of misalignment
Authors: Foote Kenneth G. , Tjo/tta Jacqueline Naze , Tjo/tta Sigve
Published: October 2005

The difference frequency sound field from two concentric but misaligned, axisymmetric, planar transducers in a nondissipative and nondispersive medium is developed as a special case of the general theory [Garrett et al., J. Acoust. Soc. Am. 75, 769–779 (1984)]. Effects of misalignment of pump, source, and hydrophone on the performance of the parametric receiving array are quantified in numerical examples. These include the effect of interaction in the nearfields of both pump and source transducers. The results show that the best performance is obtained for good alignment, high pump frequency, and placement of the hydrophone within or not far from the source nearfield.
Basic singular solutions for a poroelastic medium in the dynamic range
Authors: Bonnet Guy
Published: October 2005

The basic singular solution to the problems of dynamic poroelasticity is produced in analogy with thermoelasticity. The solution, given for a harmonic excitation, is valid for all distances and the whole frequency range by analytical expressions.
Inhomogeneous wave generation and propagation in lossy anisotropic solids. Application to the characterization of viscoelastic composite materials
Authors: Hosten B. , Deschamps M. , Tittmann B. R.
Published: October 2005

This article develops a method for investigating some anisotropic media, such as composites, by the use of ultrasonic waves transmitted through a plate-shaped sample immersed in water. The discussion begins with Christoffel’s equations for plane linear anelastic waves under the assumptions that for small angles of incidence the wave modes are plane and inhomogeneous and that the anisotropy is representable by hexagonal symmetry. The water–sample interface is treated using the law of Snell–Descartes for nonabsorbing media and takes into account mode conversion and the generation of acoustic surface waves. The method produces viscoelastic constants and relative attenuation coefficients as a function of the angle of refraction. The experimental measurement apparatus is described and data are given for the 25-layer unidirectional Gr/epoxy composite. Results are presented in terms of slowness, damping vector, and attenuation curves. The results are significant in that they demonstrate the anisotropy both for the elastic stiffness and the attenuation. The method appears to hold promise for characterizing some classes of anisotropic media, including 2-D composites, in terms of their anelastic behavior.
Accents, focus distribution, and the perceived distribution of given and new information: An experiment
Authors: Nooteboom S. G. , Kruyt J. G.
Published: October 2005

This article reports on an experiment examining some perceptual consequences of correspondences between accent patterns, the distribution of plus and minus focus, and the distribution of new and given information in Dutch spoken sentences. ‘‘Accent patterns’’ refer here to the distribution of intonational accents over spoken sentences. Each accent marks a sentence constituent as plus focus, i.e., as highlighted by the speaker. Constituents not so marked are called minus focus. The main questions examined here are to what extent are plus focus constituents generally perceived as conveying new information, and minus focus constituents as conveying earlier introduced or given information. The linguistic material for the experiment was formed by brief radio news items, each two sentences long. Leading sentences determined the distribution of new and given information in target sentences. The accent patterns and, hence, the possible focus distributions in the target utterances were varied systematically by manipulating their synthetic pitch contours according to the rules for Dutch intonation. Subjects were asked to rate on a scale from 1–10 the acceptability of each possible combination of a leading with a target utterance. Results showed that the most preferred or acceptable distributions of new and given information closely match the distributions of plus and minus focus. It was also found that new information can hardly ever acceptably be associated with minus focus, but given information can rather often, although not always, acceptably be associated with plus focus. This appears to be limited to certain conditions, defined by a combination of syntactic and focus structure of the sentence. In these conditions, plus focus cannot be perceived only as signaling new information, but also as highlighting thematic relations with the context. These results are related to work on text-to-speech systems.
On the possible role of auditory short-term adaptation in perception of the prevocalic [m]–[n] contrast
Authors: Repp Bruno H.
Published: October 2005

Acoustic information about the place of articulation of a prevocalic nasal consonant is distributed over two distinct signal portions, the nasal murmur and the onset of the following vowel. The spectral properties of these signal portions are perceptually important, as is their relationship (the pattern of spectral change). A series of experiments was conducted to investigate to what extent relational place of articulation information derives from a peripheral auditory interaction, viz., short-term adaptation caused by the murmur. Experimental manipulations intended to disrupt the effects of such adaptation included separation of the murmur and the vowel by intervals of silence, presentation to different ears, and reversal of order. Other tests of the possible role of adaptation included manipulation of murmur duration, murmur–vowel cross splicing, and high-pass filtering of the excised vowel onset. While the results of several experiments were compatible with the peripheral adaptation hypothesis, others did not support it. An alternative hypothesis, that the manner cues provided by the murmur are crucial for accurate place judgments, was also discredited. It was concluded that, at least under good listening conditions, the perception of spectral relationships does not depend on peripheral auditory enhancement and probably rests on a central comparison process.
Interaction of sound waves. Part I: Basic equations and plane waves
Authors: Naze Tjo/tta Jacqueline , Tjo/tta Sigve
Published: October 2005

The nonlinear interaction of sound waves in a lossless fluid is considered theoretically. The basic equations are valid to square-order terms in the acoustic variables. The structure and origin of various terms, and their effect on the solution, are discussed. Emphasis is given to the effects of nonlinear on-source conditions, illustrated with plane wave models.
Interaction of sound waves. Part II: Plane wave and real beam
Authors: Naze Tjo/tta Jacqueline , Tjo/tta Sigve
Published: October 2005

The nonlinear interaction in a lossless fluid between an infinite plane sound wave and a sound beam generated by a real source is considered theoretically in the quasilinear approximation. The importance of a proper choice of acoustic variables and their correct on-source values are analyzed. The governing equation for the sum and difference frequency components is solved for prescribed boundary conditions. A solution uniformly valid in space is obtained in the form of a double Fourier integral. In the farfield, the integration can be performed and a simple formula is obtained. This relates the amplitude and directivity at the observation point to the on-source amplitude and phase of the beam. Relevance to earlier literature on parametric acoustic receiving arrays is also discussed.
Comments on ‘‘Attenuation measurement uncertainties caused by speckle statistics’’ [J. Acoust. Soc. Am. 8
, 727–734 (1986)]
Authors: Lin T. , Ophir J.
Published: October 2005

A general solution to the problem of ultrasonic attenuation estimation in vivo involves the use of linear least squares analysis. A recent approximate solution for the variance of the estimator assumed by K. J. Parker [J. Acoust. Soc. Am. 80, 727–734 (1986)] may be changed to an exact solution. It is shown that a simple yet exact closed form exists, and that the approximate solution is only valid over a narrow range.
Demonstration and laboratory equipment for teaching vibration and sound
Authors: Stumpf Folden B.
Published: October 2005

A list of suppliers of demonstration and laboratory equipment is provided for use in teaching vibration and sound in secondary-school and college courses. Several helpful references are also included.
Model analysis of a hammer–string interaction
Authors: Suzuki Hideo
Published: October 2005

A hammer–string interaction for the bass note (A0) of a 6-ft grand piano is investigated by use of a lumped-element model. The hammer head is simulated by a mass–spring system with a nonlinear spring characteristic. The string is simulated by many parallel resonant circuits, each of which consists of a mass, a linear spring, and a dashpot. The impulsive force applied by the hammer to the string lasts only approximately 1 ms for a hard-hit key. The string deformation at the striking point also reaches near its maximum within about this time and retains its amplitude until the wave is reflected back from the closer end at approximately 4 ms. The hammer leaves the string temporarily, since the hammer is slowly moving downward after the first impact. The string reduces its displacement rapidly when the wave is reflected back from the closer end and, consequently, it pushes the hammer farther back. Effect of hammer stiffness, hammer velocity, and inharmonicity on the spectral distribution of partials and the efficiency of energy transmission are also discussed.
Speech waveform envelope cues for consonant recognition
Authors: Van Tasell Dianne J. , Soli Sigfrid D. , Kirby Virginia M. , Widin Gregory P.
Published: October 2005

This study investigated the cues for consonant recognition that are available in the time-intensity envelope of speech. Twelve normal-hearing subjects listened to three sets of spectrally identical noise stimuli created by multiplying noise with the speech envelopes of 19 /aCa/ natural-speech nonsense syllables. The speech envelope for each of the three noise conditions was derived using a different low-pass filter cutoff (20, 200, and 2000 Hz). Average consonant identification performance was above chance for the three noise conditions and improved significantly with the increase in envelope bandwidth from 20–200 Hz. SINDSCAL multidimensional scaling analysis of the consonant confusions data identified three speech envelope features that divided the 19 consonants into four envelope feature groups (‘‘envemes’’). The enveme groups in combination with visually distinctive speech feature groupings (‘‘visemes’’) can distinguish most of the 19 consonants. These results suggest that near-perfect consonant identification performance could be attained by subjects who receive only enveme and viseme information and no spectral information.
Identification of intonation contours by normally hearing and profoundly hearing-impaired listeners
Authors: Grant Ken W.
Published: October 2005

Fundamental frequency (F0) information extracted from low-pass-filtered speech and aurally presented as frequency-modulated sinusoids can greatly improve speechreading performance [Grant et al., J. Acoust. Soc. Am. 77, 671–677 (1985)]. To use this source of information, listeners must be able to detect the presence or absence of F0 (i.e., voicing), discriminate changes in frequency, and make judgments about the linguistic meaning of perceived variations in F0. In the present study, normally hearing and hearing-impaired subjects were required to locate the stressed peak of an intonation contour according to the extent of frequency transition at the primary peak. The results showed that listeners with profound hearing impairments required frequency transitions that were 1.5–6 times greater than those required by normally hearing subjects. These results were consistent with the subjects’ identification performance for intonation and stress patterns in natural speech, and suggest that natural variations in F0 may be too small for some impaired listeners to perceive and follow accurately.
Perceptual components of pitch: Spatial representation using a multidimensional scaling technique
Authors: Ueda Kazuo , Ohgushi Kengo
Published: October 2005

Paired comparison experiments were carried out on the pitch of 18 computer-generated complex tones synthesized by slight modification of the frequency structure of Shepard’s endless scale sounds. The results were analyzed by a multidimensional scaling technique, and simple helixes were obtained in which two components of pitch (tone height and tone chroma) were represented. Some individual differences in perception of pitch were observed according to the weight that the subject gives to each component.
L
eq as a measure of annoyance caused by gunfire consisting of impulses with various proportions of higher and lower sound levels
Authors: Vos Joos , Geurtsen Frank W. M.
Published: October 2005

As a method of rating sounds with respect to the expected community response, ISO(1971). ISO R 1996, ‘‘Assessment of noise with respect to community response’’ (International organization for Standarization, Switzerland), recommends the measurement of the A-weighted equivalent sound level Leq. The usefulness of Leq for road-traffic sounds has been demonstrated in various studies. For impulse sounds, however, research into the adequacy of Leq has been very limited. The present laboratory study provides a further test of the adequacy of Leq as a descriptor of annoyance. In one condition, all impulse sounds had the same level, whereas in the other eight conditions the levels of the impulses could differ either by 6 or by 12 dB. The proportions of the impulses with high or low sound levels were 90% vs 10%, 75% vs 25%, and vice versa. Sixteen subjects compared the annoyance caused by the impulse sounds (G) with the annoyance due to road-traffic sounds (T). They adjusted the level of either T or G in such a way that these sounds were just as annoying as the standard G [Leq =40 dB(A)] or T [Leq =45 dB(A)] sounds. The results from one group of subjects showed that the degree of annoyance was about the same for all conditions, whereas the results from another group of subjects showed that Leq may overestimate the annoyance in at least some conditions. The present data, therefore, mildly support the effectiveness of Leq as a predictor of annoyance.
Multidimensional tactile displays: Identification of vibratory intensity, frequency, and contactor area
Authors: Rabinowitz W. M. , Houtsma A. J. M. , Durlach N. I. , Delhorne L. A.
Published: October 2005

Experiments were conducted to determine the ability of subjects to identify vibrotactile stimuli presented to the distal pad of the middle finger. The stimulus sets varied along one or more of the following dimensions: intensity of vibration, frequency of vibration, and contactor area. Identification performance was measured by information transfer. One-dimensional stimulus sets produced values in the range 1–2 bits and, for most subjects, three-dimensional sets produced values in the range 4–5 bits. Of the three dimensions considered, performance on the intensity variable was most affected, and performance on contactor area least affected, by simultaneous variations in the other dimensions.
Boundary reverberation rejection via constrained adaptive beamforming
Authors: Alexandrou Dimitri
Published: October 2005

The problem of selective reverberation cancellation, whereby both ‘‘signal’’ and ‘‘noise’’ are constituent components of the received reverberation process, is the focus of this article. The proposed solution involves the application of a constrained adaptive beamforming technique. The ‘‘prewindowed’’ deterministic least-squares lattice filter is used as the central adaptive element. Constraints are in the form of simple spatial filtering prior to adaptation. The spatial correlation characteristics of volume and boundary reverberation are found to be directly applicable in a reverberation cancellation context. Experimental verification is offered by processing reverberation data from a shallow-water deployment of an active sonar system. It is shown that the boundary reverberation components can be effectively suppressed while preserving the volume return. Computer simulations of the experiment offer additional insight into the adaptation process.
Reflection tomography
Authors: Abraham Phillip B. , Gaumond Charles F.
Published: October 2005

The imaging of a strong elastic scatterer located in a fluid is treated by a novel method. This consists of replacing the scatterer by equivalent source and reflectivity distributions without making any a priori assumptions about its internal structure or geometric shape. This idea leads to effective reconstruction algorithms based on farfield data. Applications are given using synthetic data obtained from the available analytic solutions of the direct scattering problem for rigid and elastic spheres. The method presented is compared with previous tomographic work and further generalizations and extensions are discussed.
Characteristics of oil industry dredge and drilling sounds in the Beaufort Sea
Authors: Greene Charles R.
Published: October 2005

As part of a general study of underwater industrial noises and their effects on bowhead whales, sounds from drilling and dredging operations were measured in the shallow waters (<50 m) of the Canadian Beaufort Sea during August of each year from 1980–1984. The measurements were made from a vertical string of hydrophones at depths of 3, 9, and 18 m suspended from a sparbuoy. Sound sources included drillships logging and drilling, drilling at a caisson-retained island, transfer dredges, and hopper dredges. Results are presented in spectrum graphs, as sound pressure levels in third-octave and octave bands, and as overall levels in the 20- to 1000-Hz band. Most energy from these sources was below 1000 Hz. The weakest drilling/dredging sounds measured came from a drillship performing logging operations (122–125 dB re:1 μPa, 20–1000 Hz, range 0.17 km). The strongest sounds came from a hopper dredge underway with a damaged propeller (150 dB, range 0.46 km). Measured data were used to derive regression equations for received sound level versus range. In these shallow waters, the overall noise (20- to 1000-Hz band) from most drilling and dredging operations would be at levels below the median ambient noise (99 dB) at ranges greater than 30 km.