bluuebunny/crossref_metadata_2025 huggingface dataset:
Ray theory versus the parabolic equation in a long-range ducted environment
Authors: Tolstoy A. , Berman D. H. , Franchi E. R.
Published: October 2005

In this paper we examine the effects as predicted by extended ray theory of a deep water SOFAR channel with a superimposed surface duct (depths from 200–800 m) on acoustic propagation for a nominal frequency of 300 Hz. Several source and receiver configurations (combinations with one or both in and out of the duct) are considered. Validity is tested by comparison of the ray-theoretic calculations with results based on the parabolic equation (PE). Both model predictions of transmission loss and acoustic field patterns agree very well. In addition, we examine the effects of two strongly refracting analytic sound-speed profiles. We find that the PE approach does not accurately locate the range of signal turning points. Subsequently we introduce a new and simple sound-speed transformation to improve those predictions.
The effect of the player’s vocal tract on woodwind instrument tone
Authors: Backus John
Published: October 2005

Many players of woodwind instruments believe that the tone of the instrument is influenced by the player’s vocal tract. If this is so, it would be expected that the vibrating reed in the player’s mouth would generate an appreciable sound pressure in his vocal tract. However, measurements of the vocal tract impedance (looking into the mouth) give values an order of magnitude less than the impedances of the clarinet air column resonances. The sound pressure built up in the vocal tract would thus be expected to be much smaller than that in the clarinet. A clarinetlike system was arranged to sound by drawing air through it from the normally open end, the reed being out in the open for easy accessibility. When the mouth was placed around the mouthpiece with the system sounding, the changes in the waveform and harmonic structure of the tone were minimal. When a system with a more sharply tuned resonance was substituted for the vocal tract, the waveform changes were observable but not large. It appears that the player’s vocal tract has a negligible influence on the instrument tone.
Ultrasonic measurement of bubble cloud size profiles
Authors: Chapelon J. Y. , Shankar P. M. , Newhouse V. L.
Published: October 2005

The detection and sizing of microbubbles have applications in many fields. A technique of insonifying bubbles simultaneously with a ‘‘pumping field’’ which is swept through their resonance frequencies, together with a higher frequency ‘‘imaging field’’ having spatial resolution, is shown to be capable of ultrasonically estimating the size distribution of microbubbles in fluids noninvasively and in real time. Experimental results are presented which show good agreement between the size profile of bubbles measured optically, and that determined from this double frequency method. The method is also shown to detect bubbles below the limit of optical observation.
Resonance sound transmission into arbitrarily loaded submerged cylindrical shells
Authors: Gaunaurd G. C. , Barlow J.
Published: October 2005

We develop the fundamental exact analytical and computational model required to study the transmission of incident plane sound waves into submerged elastic cylindrical shells subjected to arbitrary forcing functions on their outer surface. We use the superposition principle in this linear problem to separate the contributions to the internally transmitted field caused by the incident wave from that of the surface excitation. This basic model uses the exact (2-D) formulation of elastodynamics to describe the shell motions, and that of general linear acoustics to describe the wave motion in the inner and outer fluids. We display the isobaric contours of the internally transmitted pressure fields, exhibiting their caustics and their progressive development as the frequency is increased within the band 0≤k3a≤10. The contour plots are generated for all possible combinations of forcing functions and insonification conditions with a view toward computing an advantage ratio PR which measures the gains that would result from sensing the internally transmitted field, rather than the field external to the shell at its surface. This advantage ratio is shown always to be greater than unity, and in many cases, much greater than unity. The effects of two basically different types of loads are analyzed via internal isobaric plots, and also by means of spectral plots computed at selected fixed points inside the shell. We observe an encouraging overall permanence of the caustic locations, at fixed frequencies, as the types of surface loads are varied. The present investigation of sound transmission into arbitrarily surface-loaded shells clearly demonstrates the filtering behavior of the shell in the frequency domain, and its focusing action in space. Hence, for moderate surface loads, the air-filled submerged shell analyzed here acts as a very effective sound concentrator, particularly near the resonances of its monopole mode.
Comments on ‘‘Predicting frequency selectivity in forward masking from simultaneous masking’’ [J. Acoust. Soc. Am. 7
6, 1045–1050 (1984)]
Authors: Moore Brian C. J.
Published: October 2005

Lutfi [J. Acoust. Soc. Am. 76, 1045–1050 (1984)] has recently described a model in which the differences in tuning between simultaneous and forward masking are explained by a multiplicative relation between on-frequency forward and off-frequency simultaneous masking; no additional mechanism (for example, suppression) is required to explain the sharper tuning found in forward masking. The purpose of this letter is to show that the model is inconsistent with the results of a number of experiments, and cannot therefore be correct.
Effects of a compressive nonlinearity in a cochlear model
Authors: Geisler C. Daniel
Published: October 2005

A compressive nonlinearity located at the hair cell–nerve fiber complex of a cochlear model is shown to generate realistic single-tone responses, as well as to cause lifelike ‘‘synchrony suppression.’’
Travel time and geometry of steep acoustic rays subject to Gulf Stream variability
Authors: Spiesberger John L. , Malanotte-Rizzoli Paola , Welsh Elizabeth B.
Published: October 2005

A reference sound-speed profile is constructed by averaging many historical sound-speed profiles near the Gulf Stream. The travel times and geometries of steep acoustic rays between bottom-mounted sources and receivers are computed for the reference profile. The ranges are between 20 and 100 km and the ray paths which are analyzed reflect from the surface and/or the bottom. Travel times and geometries are also calculated for the same rays for sound-speed profiles computed from a measured hydrographic section which traversed the Gulf Stream. The exact travel time differences of the rays between the measured and reference profiles are compared with a linear approximation to the exact travel time differences. The linear approximation is typically within 10% of the exact travel time difference. The difference in depth of a ray path traced through the reference profile and the corresponding path traced through the measured profile is typically less than 100 m. Linearized inversion schemes should be adequate for mapping Gulf Stream variability.
An algorithm for the efficient measurement of immittance using the HP 4192A impedance analyzer
Authors: Henriquez T. A. , Ruggiero C. M.
Published: October 2005

A fully automatic method of obtaining immittance loops of electromechanical transducers has been designed to be utilized in conjunction with the Hewlett–Packard 4192A impedance analyzer. The algorithm makes use of a unique circular approximation technique that minimizes the number of frequencies required to obtain a well-defined immittance loop. A maze technique is then used to accurately calculate resonant and antiresonant frequencies.
Low-noise noise
Authors: Pumplin Jon
Published: October 2005

A practical method of computation is described for making periodic signals V(t) which have a given frequency spectrum and which minimize the variance 〈(V2−〈V〉2)2〉 in power as a function of time. These signals can be used to measure the spectral response of a system (the transfer function): They represent a significant improvement over traditional random-phase and minimum peak value approaches. The signals are also of psychophysical interest.
Implications of multipath propagation for two-frequency coherence measurements
Authors: Birdsall T. G. , Khan F.
Published: October 2005

The underwater acoustic medium is modeled as a deterministic multipath channel. A moving source transmits two pure sinusoidal signals. The receiver separates the signals by filtering, and then demodulates them. Two-frequency coherence is defined as the normalized cross correlation of the two demodulates. A new measurement technique is suggested whereby it is shown that: (1) the coherent bandwidth for a channel with only deterministic multipaths is essentially unlimited and (2) paths of significant gain may be resolved by using long measurement times. A lower bound on measurement time for path resolution is obtained.
Image reconstruction from disturbed synthetic aperture sonar data using aperture division
Authors: Ikeda Osamu , Sato Takuso , Minamide Yasuo , Fukushima Akira
Published: October 2005

An image reconstruction algorithm based on disturbed synthetic aperture sonar data is presented. First, the data are divided on the basis of aperture and the images are then reconstructed from the divided data. For a smoothly varying phase disturbance these images are shifted in the azimuth direction corresponding to the local tilts of the disturbance, so that detection of these shifts enables the disturbance to be estimated and thus compensation can be made for the disturbed data. A reflector is placed in or around the object to be observed in order for the algorithm to apply to a general class of objects. The optimum size of the subapertures can be determined from the same data. The principle of the method and some typical numerical examples are given.
Variable density acoustic tomography
Authors: Devaney A. J.
Published: October 2005

The theory and algorithms of diffraction tomography are generalized to the case of acoustic objects whose density and compressibility vary as a function of position. A generalized projection-slice theorem is presented for objects of this class and filtered backpropagation algorithms are derived that allow separate reconstructions of the objects’ density and compressibility using measurements of the transmitted acoustic field performed at two distinct frequencies. Computer simulations are presented testing the algorithms in the noise-free case.
Sonoluminescence produced by ‘‘stable’’ cavitation
Authors: Crum L. A. , Reynolds G. T.
Published: October 2005

This article reports on a phenomenological study of sonoluminescence produced by acoustic cavitation in which a sensitive, high-gain image intensifier tube (EMI type 9912) was used to view the cavitation. We discovered that large amounts of light were being emitted from regions near pressure antinodes in the standing wave field where the pressure amplitude was approximately 0.17±0.03 MPa. Visual observation of these areas indicated activity resembling ‘‘stable’’ cavitation rather than ‘‘transient’’ cavitation.
Ultrasonic relaxation measurements in N2O–pH2 and N2O–nH2 mixtures at 300 K
Authors: Sidwell S. C. , Amme R. C. , Neumann H.
Published: October 2005

A variable-path ultrasonic interferometer with a 300-kHz quartz crystal driver was used to study dispersion at 300.2 K in N2O–pH2 and N2O–nH2 mixtures with 0%–5% H2. The vibrational relaxation time of pure N2O was found to be 0.975(7) atm μs. Evidence was found for vibration-rotation transfer to oH2 with a probability of about 30% of the vibration-translation probability.
Accuracy, latency, and listener-search behavior in localization in the horizontal and vertical planes
Authors: Noble William , Gates Anne
Published: October 2005

Thirty-six listeners localized continuous filtered noise bursts centered on 2.3 or 8.3 kHz under normal listening conditions or while wearing earmuffs. The noise bursts were from any one of 20 loudspeakers, 18° apart, visible to the listeners, and arranged in the horizontal and vertical planes. Listeners were free to move, while remaining seated, throughout all trials. The noise bursts were terminated by the listeners. Measures of accuracy and latency showed that earmuff listening had a significant effect whereas, overall, signal frequency had no significant effect. There was, however, an apparent downward shift of the 2.3-kHz signals presented above the midline in the vertical plane. Analysis of video records of listeners’ behavior revealed a strong tendency for initial orientation by head or eye movement to correlate with final response, even when both were inaccurate. The paradigm adopted in this latter aspect of the study illustrates an ‘‘ecological’’ approach to the study of auditory phenomena.
A method for solving free vibration problems of three-layered plates with arbitrary shape
Authors: Poltorak Krzysztof , Nagaya Kosuke
Published: October 2005

This paper deals with a method for solving free vibration problems of three-layered isotropic plates of arbitrary shape with clamped edges. The direct solution of the Yan and Dowell equation of motion, in terms of Bessel functions, is found. The boundary problem is solved by means of the Fourier expansion collocation method. Nondimensional frequency parameters for circular, elliptical, square, and triangular plates with clamped edges are calculated for a wide range of dimension ratios and two typical material configurations. The validity of the method is also discussed.
Panel vibration damping due to sound-absorbing liners
Authors: Trochidis A.
Published: October 2005

A mechanism of panel vibration damping due to the addition of absorbing liners is discussed. An expression for the loss factor associated with the described damping mechanism is derived. It predicts satisfactorily not only the observed damping but also its dependence on the vibration frequency, the acoustical impedance of the sound-absorptive material, and the separation distance between the panel and absorbing liner surfaces.
Laser-induced thermoacoustic radiation
Authors: Berthelot Yves H. , Busch-Vishniac Ilene J.
Published: October 2005

When an intensity-modulated laser beam illuminates a column of water, it produces, via thermal expansion, a highly directive sound beam. The pressure field radiated by such a thermoacoustic source is analyzed, first by determining the impulse response of the system. The thermoacoustic pressure is then expressed as a convolution between the impulse response and the time derivative of the laser intensity. The analysis is valid in both the nearfield and the farfield of the source and, in principle, for any spatial or temporal distribution of the laser intensity. This approach provides valuable insight into the nearfield of this type of transducer. Resulting theoretical predictions of pressure waveforms and directivity patterns compare well to experimental results, and agree in the farfield limit with existing farfield analyses of thermoacoustic radiation.
Acoustic scattering by a rigid movable body immersed in a fluid
Authors: Olsson Peter
Published: October 2005

The problem of scattering of acoustic waves, by a rigid movable body immersed in a fluid, is solved by means of the null-field approach. The solution is obtained both directly and as a limit of the solution for an elastic body. Numerical results are presented for some rotationally symmetric bodies.
Discrimination and identification of frequency-lowered speech in listeners with high-frequency hearing impairment
Authors: Reed Charlotte M. , Schultz Kenneth I. , Braida Louis D. , Durlach Nathaniel I.
Published: October 2005

The effects of frequency lowering on consonant perception were studied in four listeners with high-frequency sensorineural loss. Frequency lowering, accomplished by pitch-invariant nonuniform compression of the short-term spectral envelope, included lowering to bandwidths of 2500 and 1250 Hz. Performance on frequency lowering was compared to that obtained with linear amplification using uniform or high-frequency emphasis. Results of pairwise discrimination tests indicated that performance on lowering to 1250 Hz was inferior to that obtained with linear amplification. After training, performance on consonant identification with lowering to bandwidths of 2500 or 1250 Hz was equivalent or inferior to that obtained with linear amplification, depending on the subject. In most cases, the performance of the impaired subjects on a given lowering condition was inferior to that obtained by normal subjects, except for one impaired subject whose performance on two lowering conditions was similar to normal.
Comments on ‘‘Re-analysis of data presented in ‘Community response to blasting’ ’’ [J. Acoust. Soc. Am. 7
8, 799–800 (1985)] and ‘‘Reply to ‘Re-analysis of data presented in ‘Community response to blasting’ ’ ’’ [J. Acoust. Soc. Am. 7
8, 800–801 (1985)]
Authors: Kessler Frederick M.
Published: October 2005

The reply to the re-analysis was written to the first draft of the letter, since the author did not see the revised final draft. [AIP]
Parabolic equation modeling of shear waves
Authors: Tappert F. D.
Published: October 2005

A simple technique is derived for including in the parabolic equation underwater acoustic propagation model the losses due to conversion of compressional waves into shear waves at the water–bottom interface.
A model of acoustic backscatter from Arctic sea ice
Authors: Greene Robert R. , Stokes A. Paul
Published: October 2005

A model of acoustic backscatter from Arctic sea ridge keels is developed. The model is demonstrated to produce good agreement with data. It is a composite surface scattering theory based on diffractive scattering from small-scale roughness on the flanks of randomly oriented triangular ridge keels.
The dispersion of sound in sediment
Authors: Wingham Duncan J.
Published: October 2005

The attenuation of sound through a wide variety of sediments is proportional to the first power of frequency. In order that a plane wave remain causal after suffering such an attenuation, it must also be dispersed. The dispersion necessary to maintain causality in typical sediment is shown to have a logarithmic dependence on frequency and to be measurably large. A truncated parametric array is used to provide a wideband pulse whose travel through a typical medium sand is observed. The measured dispersion is in agreement with the theoretical prediction, exhibiting a variation in phase velocity of 0.5% across a frequency range of 50–350 kHz.
Insufficiency of surface spatial power spectrum for estimating scattering strength and coherence: Numerical studies
Authors: Kinney Wayne A. , Clay C. S.
Published: October 2005

The facet-ensemble method [W. A. Kinney et al., J. Acoust. Soc. Am. 73, 183–194 (1983)] is used to determine if the spatial wavenumber power spectrum of a rough surface is sufficient to predict the amplitude and spatial coherence of acoustic energy scattered from that surface. Two sets of water surfaces are studied. Within each set, the surfaces have the same rms roughness (0.2 cm) and spatial power spectrum. For each surface, the acoustic field in the water is computed at two omnidirectional receivers for both backscatter and forward scatter at a grazing angle of 35°. The source emits a 100-kHz signal and has a beamwidth of 13°. The total travel distance is 506 cm. Results indicate that the backscattered energy is more sensitive to detailed surface shape than is the forward scattered energy. This implies that the surface spatial power spectrum may not be sufficient to predict backscatter accurately.
Shape oscillations of microparticles on an optical microscope stage
Authors: Zhu Zhe-ming , Apfel Robert E.
Published: October 2005

A modulated acoustic radiation pressure technique to produce quadrupole shape oscillations of drops ranging in diameter from 50–220 μm has been used by us. These drops have been suspended by acoustic levitation in a small chamber mounted on a stage of an optical microscope, which allowed easy viewing. The fission of drops and the deformation of sea urchin eggs were also observed.
Elastic waves in heterogeneous waveguides of rectangular cross section
Authors: Touratier Maurice , Maugin Gérard A.
Published: October 2005

In this paper a theoretical and experimental analysis is proposed for elastic wave propagation in heterogeneous waveguides of a rectangular cross section. A formulation is presented which is based on approximate fields of displacement and stress which satisfy exactly the continuity conditions at interfaces and boundary conditions on lateral faces. Two types of waveguides are envisaged: a so-called rectangular clad-core guide and a guide made of three superimposed layers, the materials involved being orthotropic. The linear elastodynamics of these guides is deduced from a two-field variational formulation of the Hellinger–Reissner type. Dispersion spectra are constructed for both types of waveguides depending on the concentration and relative arrangement of the different materials which build up the guides. Geometrical and material conditions deduced from the values of asymptotic speeds are proposed in order to guarantee the propagation of a certain mode in a prescribed region of the guide. Dispersion gauges are introduced with a view to controlling the dispersion which strongly depends on the nature and arrangement of materials. Experimental results obtained by a resonance method are reported for the two types of rectangular guides. The dispersion observed and the existence of guided modes are reported. Finally, comparison is made between theoretical predictions and experimental results, which proves that the predictions were correct.
Scattering matrix of a discontinuity with a nonrigid wall in a lossless circular duct
Authors: Hudde Herbert , Letens Uwe
Published: October 2005

An abrupt change of cross section in a circular lossless duct is considered. The analysis includes a nonrigid wall at the interface of both parts of the duct. Whereas previous investigators used iterative algorithms to calculate the behavior of the discontinuity, here a straightforward method is developed which avoids any convergence problems. In particular, large discontinuities can also be examined even if an arbitrary number of higher wave modes can propagate. The solution is given in form of a scattering matrix. For the plane wave mode a simple equivalent circuit is derived. The results are compared to an approximate solution given by Karal [J. Acoust. Soc. Am. 25, 327–334 (1953)] and to a measurement. At low frequencies all data agree excellently. Some scattering parameters for different cases (different size of discontinuities, different wall admittances, difference frequency ranges) are represented. It is demonstrated that the magnitude of certain scattering parameters can exceed unity, if the corresponding wave is evanescent.
Inverse acoustic scattering for one-dimensional lossy media
Authors: Rorres Chris , Bai Jing , Pedersen Peder C. , Tretiak Oleh J.
Published: October 2005

An algorithm for the reconstruction of the physical parameters of a layer of an attenuating medium is presented. The parameters are to vary only along the thickness of the layer. The input data for the algorithm consist of the reflection coefficients of two incident time-harmonic plane waves intersecting the layer at two different angles. Using scattered data, the density variation of the medium is determined, as is the spatial variation of its attenuation coefficient. The frequency variation of the attenuation is assumed to be known. The reconstruction algorithm is based on the impediography formula modified to account for non-normal incident waves and for the attenuation of the medium. Several numerical examples of the algorithm are presented using computer-generated input data for media with specified density and attenuation variations.
Short wave analysis for the reflection of bounded acoustic beams onto liquid–solid interfaces at the Rayleigh incidence
Authors: Rousseau M. , Gatignol Ph.
Published: October 2005

Experimental studies about the reflection of bounded acoustic beams onto plane liquid–solid interfaces show that for an incidence at or near the Rayleigh angle, the reflected field exhibits unexpected properties. In particular, this phenomenon has been observed ten years ago by Neubauer and it is now well understood: The key is the reradiation in the liquid medium of the Rayleigh wave generated by coupling with the incident beam. Theoretical descriptions of this feature have been proposed that are based upon asymptotic or numerical considerations on the velocity distribution along the interface. In this paper, these previous theories are enlarged in the following sense: The incident beam is now defined by its velocity distribution along a plane emitter; the reflected beam is described through its pressure field in a region which is not restricted to the interface; several incident beam profiles are considered. Moreover, the short wave asymptotic analysis is different from the previous ones; here field integral representations are evaluated by means of the steepest-descent method.
A propagator model for scattering of acoustic waves by bubbles in water
Authors: Varadan V. K. , Varadan V. V. , Ma Y.
Published: October 2005

A propagator model is presented for acoustic wave propagation through a bubble swarm. Both phase velocity and coherent attenuation are studied as a function of frequency and compared with experimental measurements of Silberman [J. Acoust. Soc. Am. 29, 925 (1957)].
Nearfield of a piston source of ultrasound in an absorbing medium
Authors: Nyborg Wesley L. , Steele R. Bruce
Published: October 2005

Approximate expressions are discussed which are applicable for acoustic quantities in the vicinity of a plane piston source of ultrasound which radiates into an absorbing medium. A particularly useful approach for nearfield calculations combines an expression valid near the axis with another, given by Pierce [Acoustics, An Introduction to Its Physical Principles and Applications (McGraw-Hill, New York, 1981), Chap. 5], which is valid elsewhere. This approach gives reasonable accuracy at relatively low computational cost. Computed plots are presented, showing spatial distributions of the square of the pressure amplitude. Most of the plots are for a source diameter of 1.2 cm, a frequency of 3 MHz, and an absorption coefficient of 0.15 Np/cm; these are representative of conditions for medical applications of ultrasound.
An optical telemetry device to identify which dolphin produces a sound
Authors: Tyack Peter
Published: October 2005

A small telemetry device, called a ‘‘vocalight,’’ was designed for attachment to a dolphin’s head using a suction cup. The vocalight lights up a variable number of light-emitting diodes depending upon the loudness of sounds received at a hydrophone within the suction cup. If vocalights matched for sensitivity are put on each dolphin within a captive group, observers can identify which dolphin produces a vocalization. Use of vocalights indicates that source levels of whistles from captive bottlenosed dolphins, Tursiops truncatus, range from approximately 125 to over 140 dB re: 1 μPa at 1 m.
Level effects in complex stimulus discrimination
Authors: Turner Christopher W. , Cacace Anthony T.
Published: October 2005

The dependence of spectral-shape discriminations upon presentation level was studied using stimuli consisting of a bandpass noise and a less intense pure tone. The level of the noise band was held constant (+10 dB) relative to the level of the tone, and the minimum change in the intensity of the tone was measured across a range of presentation levels. The results demonstrated that, for tonal frequencies located near the upper edge of the noise band, subject’s optimal performance occurred at intermediate presentation levels and became considerably poorer at high levels. This result is in accordance with upward spread of masking and emphasizes that presentation level is an important parameter to consider when measuring discriminations of complex spectral shapes.
Requirements and techniques for measuring the musical spectrum of the clarinet
Authors: Benade A. H. , Larson C. O.
Published: October 2005

Meaningful spectrum measurement of musical instruments requires proper specification of the player’s task and proper specification of the instrument itself (in both musical and physical terms). Variations in the room transmission characteristic may be averaged over by moving-source, moving-microphone techniques based on current knowledge of the sound field statistics of rooms, and taking into account the angular distribution of the radiated instrumental sound. Detailed discussion of these matters is presented, built around a report on the measurement of two notes on each of six well-documented clarinets. The lower odd partials have variations of only ±1 dB. For all other partials the variation is ±2 dB arising from all causes. This variation is accounted for about equally by inter-instrument differences and by player instability. Systematic features of the clarinet spectrum are shown to correlate well with theoretical expectation, and perceptual implications are briefly discussed.
Quantitative investigation of disk ultrasonic sources
Authors: Aindow J. D. , Markiewicz A. , Chivers Robert C.
Published: October 2005

Computational and measured results of the phase and amplitude distributions of the fields radiated by four circular sources are presented. The limitations of the results are discussed, indicating that meaningful comparison is possible only for planes in and beyond the near- and farfield transition regions. The inclusion of an effective radius into the theoretical calculations of a piston in a rigid baffle gives generally good agreement between experiment and theory. The inclusion of the finite size of the receiver produces an additional small improvement. The phase distributions are clearly seen to be a more sensitive index of the field structure than the amplitude distributions commonly used. The value of the work is in suggesting conditions under which one or two amplitude measurements in the field may be used to define effective parameters for an ideal theoretical computation which bears a close resemblance to the actual field radiated by an (imperfect) probe.
Intrinsic fundamental frequency of vowels in sentence context
Authors: Shadle Christine H.
Published: October 2005

High vowels have a higher intrinsic fundamental frequency (F0) than low vowels. This phenomenon has been verified in several languages. However, most studies of intrinsic F0 of vowels have used words either in isolation or bearing the main phrasal stress in a carrier sentence. As a first step towards an understanding of how the intrinsic F0 of vowels interacts with intonation in running speech, this study examined F0 of the vowels [i,a,u] in four sentence positions. The four speakers used for this study showed a statistically significant main effect of intrinsic F0 (high vowels had higher F0). Three of the four speakers also showed an interaction between intrinsic F0 and sentence position such that no significant F0 difference was observed in the unaccented, sentence-final position. The interaction was shown not to be due to vowel neutralization or correlated with changes in the glottal waveform shape, as evidenced by measures of the first formant frequency and spectral slope. Comparison with studies of tone languages and speech of the deaf suggests that both the lack of accent and the lower F0 caused the reduction in the intrinsic F0 difference.
The effect of competing melodies on melody recognition by hearing-impaired and normal-hearing listeners
Authors: de Laat J. A. P. M. , Plomp R.
Published: October 2005

For a group of 30 hearing-impaired subjects and a matched group of 15 normal-hearing subjects (age range 13–17) the following data were collected: the tone audiogram, the auditory bandwidth at 1000 Hz, and the recognition threshold of a short melody presented simultaneously with two other melodies, lower and higher in frequency, respectively. The threshold was defined as the frequency distance required to recognize the test melody. It was found that, whereas the mean recognition threshold for the normal-hearing subjects was five semitones, it was, on the average, 27 semitones for the hearing-impaired subjects. Although the interindividual spread for the latter group was large, it did not correlate with the subjects’ auditory bandwidth, nor with their musical experience or education.
Is real-ear attenuation at threshold a function of hearing level?
Authors: Berger E. H.
Published: October 2005

In the course of measuring the real-ear attenuation at threshold (REAT) of experimenter-inserted E-A-R■ foam earplugs on 100 subjects, a statistically significant correlation was observed between attenuation and hearing level (for normal listeners, HTL ≤20 dB) at test frequencies from 2–8 kHz. Listeners with more sensitive hearing obtained better protection. The relationship was most robust at 6 and 8 kHz. For hearing levels greater than 20 dB, attenuation appeared independent of hearing level. A hypothesis was developed to explain the relationship for the normal listeners, based upon the fact that the high-frequency attenuation of the earplug was nearly bone-conduction limited. The hypothesis suggested that the attenuation of a hearing protector that provided substantially lower protection would not exhibit the same relationship. Data for such a device were collected for 70 subjects, and indeed demonstrated reduced correlation between attenuation and hearing level. Implications of the results of the experiments are discussed with regard to (a) hearing level requirements for hearing protector attenuation test subjects, (b) utilization of hearing-impaired listeners to measure REAT at suprathreshold (with respect to normal listeners) sound pressure levels, and (c) linearity of hearing protector attenuation as a function of sound level.
Changes in the phase of excitor-tone responses in cat auditory-nerve fibers by suppressor tones and fatigue
Authors: Deng Li , Geisler C. Daniel
Published: October 2005

The responses of single auditory-nerve fibers in anesthetized cats to two-tone stimuli were studied. One of the two tones, F1, was near, above, or below characteristic frequency (CF). The second tone, F2, was located above CF. With sufficient care, F2 was made purely suppressive, eliciting no synchrony responses by itself. The vector phases of the associated period histogram calculated for F1 were carefully studied. For 78% of the fibers under study, a statistically significant increase in phase lag was consistently observed when a suppression of rate discharge occurred. The phase-intensity curve did not approximate a horizontally shifted version of the unsuppressed curve, as is seen for the related rate- and synchrony-intensity curves; rather, the amount of phase shift at any one stimulus condition tended to be monotonically related to the amount of rate suppression generated (vertical shift). Using two different measures, a significant correlation was found between the added phase lag and the discharge-rate reduction caused by F2. The amount of phase lag, along with the corresponding rate reduction, increases with the increasing intensity of F2 within the suppression area, and decreases as F2 moves away from it. These phase-lag effects were found to be uncorrelated with a fiber’s CF, with its spontaneous rate, with its threshold, or with its Q value. By contrast, a reduction of discharge rate due to adaptation was not accompanied by any significant phase shift. Fatigue of the fiber due to lengthy sound exposure was found to have strong effects on the shift of response phase to single-tone stimuli.
Click lateralization is related to the β component of the dichotic brainstem auditory evoked potentials of human subjects
Authors: Furst Miriam , Levine Robert A. , McGaffigan Patricia M.
Published: October 2005

The changes in perception and in the binaural difference waveform (BD) for dichotic clicks with interaural time and level differences (ITDs and ILDs) are compared. Only β, the first major peak of the BD, correlated with the perceptual measurements. Whenever β is clearly present, the clicks are perceived as a unitary fused image. Whenever the clicks are perceived as not fused, β is undetectable by our methods. The amplitude of β remains nearly constant as the ITD is increased to about 1 ms, while the click’s position is perceived as moving from midline toward the leading ear. Over about the next 0.2 ms, β becomes undetectable, as the image stops moving and loses its fused quality. As the ILD is increased, β amplitude decreases gradually, while the image remains unitary and moves toward the unattenuated earphone. Thus β becomes undetectable for ILDs of 30 to 35 dB, and the dichotic clicks become indistinguishable from monotic clicks for ILDs of 44 to 53 dB. The ITD and ILD matching curve for β latency is similar to the ITD and ILD psychophysical matching curve for lateralization. These results suggest that β is a physiological correlate of the categorical percept, binaural fusion, and is generated by a brainstem structure essential for the preception of click lateralization.
A reduced-complexity quadratic structure for the detection of stochastic signals
Authors: Poor H. Vincent , Chang Chein-I
Published: October 2005

Quadratic detection of discrete-time stochastic signals in additive stationary Gaussian noise is considered. A banded-quadratic detector structure is introduced to reduce the multiplicative complexity and data storage requirements of the optimum full-quadratic detector, and the optimization of this reduced-complexity structure is studied. The issue of performance versus complexity is explored for the specific problems of detecting wide-sense Markov and triangularly correlated signals in white noise, with the conclusion that performance of the reduced complexity detector can be very close to optimum if an adequate quadratic-form bandwidth is chosen.
Passive localization using time delay estimates with sensor positional errors
Authors: Quazi Azizul H. , Lerro Donald T.
Published: October 2005

Target localization in a passive sonar system involves bearing and range estimation. These estimates may be determined using (1) the differential time delays of the source-signal arrivals at spatially separated sensors and (2) knowledge of the sensor geometry. When the sensor positions are known exactly, the accuracy of the bearing and range estimates depends on the accuracies of the differential time delays. The time delay errors depend on the signal-to-noise ratio (SNR) and on other signal and noise parameters such as bandwidth, center frequency, observation time, and spectral slopes. A critical factor in bearing and range estimation is the sensor positional errors. Here, the combined effect of time delay errors due to finite SNR and sensor positional errors on the bearing and range estimates of the acoustic source are investigated. For low-input SNR, the analysis indicates that localization errors are heavily dependent on the SNR at the individual sensors. For high SNR, sensor positional errors are the dominant factor in the localization errors. Also, the effects of the nonlinear transformation of differential time delays and sensor positions on bearing and range estimates are investigated. It is shown that the bias due to the nonlinear transformation introduced in bearing estimation is negligible for sources close to broadside, and the bias in the range estimation is always positive. The mean square range error, which includes standard deviation and bias, is then evaluated and discussed in terms of true range, variances of bearing, and unbiased range errors.
The frequency-domain grating
Authors: Hartmann W. M.
Published: October 2005

It is shown that a complex tone can be analyzed into its harmonics by adding to it a series of N−1 similar complex tones with uniformly spaced fundamental frequencies. The harmonics appear in a time-ordered sequence, and this is the basis of a computer music effect employed by composer Jean-Claude Risset. The mathematical derivation involves the summing of a geometric progression to form a slowly varying amplitude factor. The effect is directly analogous to the analysis of white light into its constituent colors by a diffraction grating with N slits. The temporal ordering of the sequence does not depend upon the relative phases of the harmonics of the complex tone, nor upon the number of tones which is summed, nor is it sensitive to amplitude changes. The order can be changed by a progressive delay of any harmonic in the summed complex tones. Calculations are made to investigate the stability of the effect against randomness is the tones to explain why the effect does not normally appear in vocal or instrumental choruses.
Editorial comment and critique of ‘‘Syllable identification by children and adults for two task conditions’’ [J. Acoust. Soc. Am. 7
7, 1258 (1985)]
Authors: Repp Bruno H.
Published: October 2005

In a recent Letter to the Editor, Elliott and Busse [J. Acoust. Soc. Am. 77, 1258 (1985)] compare children’s syllable identification thresholds in two task conditions and find no difference. However, they fail to make clear why a difference should have been expected. Without such a clarification, the experiment seems to have been a meaningless exercise.
Comments on the peer review process
Authors: Elliott Lois L. , Busse Lu Ann
Published: October 2005

Clear principles of peer review govern scientific activities in this country and elsewhere. In our opinion, these principles were abrogated by the Associate Editor in the handling of our letter. Very little perceptual research involving children is completely above criticism, and we do not mean to imply that our work is an exception. However, we think it made a positive contribution to the field. Even more firmly, we think that the real issue here is the peer review process, which far overshadows the importance of our manuscript. Perhaps this is why the late Editor-in-Chief, on his initiative and not ours, decided to publish our letter.
Comment on ‘‘Effects on environmental variables on truck noise emission and noise propagation to test microphones’’ [J. Acoust. Soc. Am. 7
6, 1150–1160 (1984)]
Authors: Morrison D.
Published: October 2005

The topic of a recent paper published in this Journal [Hemdal et al., J. Acoust. Soc. Am. 76, 1150–1160 (1984)] focused on the effects of environmental variables on noise propagation. The article states that a temperature decrease causes an increase in power and as a result an increase in noise. Early noise prediction formulae showed that significant factors for a combustion system are bore size and speed. A power term was not used, thus indicating that there is no necessary correlation between engine power and noise [AIP].
Comment on ‘‘Boundary effects on transient radiation fields from vibrating surfaces’’ [J. Acoust. Soc. Am. 7
7, 907–915 (1985)]
Authors: Greenspan Martin
Published: October 2005

The results in the Appendix of this paper, up to Eq. (A9) inclusive, and the method of derivation as well, have long since been anticipated.
Response to ‘‘Comment on ‘Boundary effects on transient radiation fields from vibrating surfaces’ ’’ [J. Acoust. Soc. Am. 7
8, 1439 (1985)]
Authors: Guyomar Daniel , Powers John
Published: October 2005

The authors apologize for not citing Greenspan’s paper in the Appendix of their original article.
Perceptual aspects of synthesized approximations to melody
Authors: Watkins Anthony J.
Published: October 2005

A procedure is described for synthesizing tone sequences that contain a high proportion of events that are likely to be found in melodies that occur in music. This is done by using a random-number generator with probability weightings that favor the selection of certain notes and intervals. The form of the probability weightings derives from constraints on the ‘‘semitone span’’ of the intervals, the ‘‘fifth span’’ of the intervals, and the occurrence of ‘‘scale’’ notes. The role of ‘‘redundancy’’ is also considered. In this way it is possible to obtain melodies that obey various combinations of the different constraints. Other melody variables are either fixed, randomized, or controlled. These experimental melodies were used in a test of the hypothesis that the more melodious tone sequences will be easier to organize perceptually and remember than less melodious sequences of equal redundancy. A psychophysical scaling procedure confirmed that the constraints generated tone sequences bearing degrees of perceptual similarity to ‘‘real’’ melodies. Melody discrimination was also measured. The ‘‘fifth span’’ and ‘‘scale’’ constraints increased the melodiousness of tone sequences. They also improved performance on tasks requiring the discrimination of unfamiliar, untransposed melodies, and the discrimination of transposed melodies after some familiarization. It is argued that general perceptual principles do not give a complete account of the perception of melody: A full description requires consideration of the listener’s tacit musical ‘‘knowledge’’ and its interaction with perceptual processes.
Perceptual equivalence of acoustic cues that differentiate /r/ and /l/
Authors: Polka Linda , Strange Winifred
Published: October 2005

The perceptual effects of orthogonal variations in two acoustic parameters which differentiate American English prevocalic /r/ and /l/ were examined. A spectral cue (frequency onset and transition of F2 and F3) and a temporal cue (relative duration of initial steady state and transition of F1) were varied in synthetic versions of ‘‘rock’’ and ‘‘lock.’’ Four temporal variations in each of ten stimuli of a spectral-cue continuum were generated. Phonetic identification and oddity discrimination tasks with the four series showed systematic displacement of perceptual boundaries and discrimination peaks, thus reflecting a trading relation between the two cues. The perceptual equivalence of spectral and temporal cues was investigated by comparing the accuracy of discrimination of three types of stimulus comparisons: phonetically facilitating two-cue pairs, one-cue pairs, and phonetically conflicting two-cue pairs. As predicted, discrimination accuracy was ordered: facilitating cues > one cue > conflicting cues, indicating that perceivers discriminated on the basis of an integrated phonetic perception.
Simultaneous masking by gated and continuous sinusoidal maskers
Authors: Bacon Sid P. , Viemeister Neal F.
Published: October 2005

Simultaneous masking of a 20-ms, 1-kHz signal was investigated using 50-ms gated and continuous sinusoidal maskers with frequencies below, at, and above 1 kHz. Gated maskers can produce considerably (5–20 dB) more masking than continuous maskers, and this difference does not appear to result from the spread of energy produced by gating either the masker or the signal. For masker frequencies below the signal frequency, this difference in masking is primarily due to the detection of the cubic difference tone in the continuous condition. For masker frequencies at and above the signal frequency, the difference appears to be an important property of masking. Implications of this frequency-dependent effect for measures of frequency selectivity are discussed.
Behavioral audiograms of the bullfrog (R
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Authors: Megela-Simmons Andrea , Moss Cynthia F. , Daniel Kimberly M.
Published: October 2005

Reflex modification was used in a psychophysical technique to measure absolute auditory sensitivity of two species of anurans. Behavioral audiograms for these animals reveal that the bullfrog can detect sounds from 100 Hz to 3.2 kHz and the green tree frog from 100 Hz to 5 kHz. The shape and the sensitivity of these behavioral audiograms are similar to those of neural evoked-response audiograms of these animals. Absolute auditory sensitivity of anurans is only partially related to the spectral composition of their species-specific vocalizations.