bluuebunny/crossref_metadata_2025 huggingface dataset:
Perception of pitch movement on tonic syllables in British English
Authors: Ainsworth W. A. , Lindsay D.
Published: October 2005

A set of intonation contours has been synthesized using ‘‘yes’’ as the carrier word. Discrimination and identification functions have been obtained for these intonation contours. It was found that the stimuli could be classified as ‘‘statement,’’ ‘‘question,’’ ‘‘emphatic statement,’’ and, possibly, ‘‘hesitation’’ and ‘‘weak statement.’’ Predicted discrimination functions were calculated from the identification functions, and these were found to be positively correlated with the obtained discrimination functions. This provides evidence for category boundary effects in the perception of intonation.
Speechreading supplemented with auditorily presented speech parameters
Authors: Breeuwer M. , Plomp R.
Published: October 2005

Results are reported from two experiments in which the benefit of supplementing speechreading with auditorily presented information about the speech signal was investigated. In experiment I, speechreading was supplemented with information about the prosody of the speech signal. For ten normal-hearing subjects with no experience in speechreading, the intelligibility score for sentences increased significantly when speechreading was supplemented with information about the overall amplitude of the speech signal, information about the fundamental frequency, or both. Binary information about voicing appeared not to be a significant supplement. In experiment II, the best-scoring supplements of experiment I were compared with two supplementary signals from our previous studies, i.e., information about the sound-pressure levels in two 1-oct filter bands centered at 500 and 3160 Hz, or information about the frequencies of the first and second formants from voiced speech segments. Sentence-intelligibility scores were measured for 24 normal-hearing subjects with no experience in speechreading, and for 12 normal-hearing experienced speechreaders. For the inexperienced speechreaders, the sound-pressure levels appeared to be the best supplement (87.1% correct syllables). For the experienced speechreaders, the formant-frequency information (88.6% correct), and the fundamental-frequency plus amplitude information (86.0% correct), were equally efficient supplements as the sound-pressure information (86.1% correct). Discrimination of phonemes (both consonants and vowels) was measured for the group of 24 inexperienced speechreaders. Percentage correct responses, confusion among phonemes, and the percentage of transmitted information about different types of manner and place of articulation and about the feature voicing are presented.
The use of auditory and phonetic memory in vowel discrimination
Authors: Cowan Nelson , Morse Philip A.
Published: October 2005

A commonly held assumption about memory for speech is that auditory memory is referred to only if phonetic memory does not contain the information needed for a particular trial. However, this assumption is in conflict with recent evidence [Crowder, J. Exp. Psychol.: Learning, Memory, Cognition 8, 153–162 (1982); Repp et al., J. Exp. Psychol.: Human Perception Performance 5, 129–145 (1979)]. The present study provides additional data to help determine how auditory and phonetic memory are used in a vowel discrimination task, and what happens during memory decay. Experiment 1 was conducted to determine whether performance levels decline at similar rates on between- and within-category AX vowel comparison trials when certain methodological problems are removed. This was confirmed. Experiment 2 demonstrated that in the AX task there is a vowel order effect, as Repp et al. found, but that this effect increased across interstimulus delay intervals, in contrast to their findings. The results can be accommodated with a model in which the memory for a vowel is represented as a small, bounded area within the vowel space, and in which memory decay is represented by the expansion of that bounded area over time.
Differential use of temporal cues to the /s/–/z/ contrast by native and non-native speakers of English
Authors: Flege James Emil , Hillenbrand James
Published: October 2005

This study examined the effect of linguistic experience on perception of the English /s/–/z/ contrast in word-final position. The durations of the periodic (‘‘vowel’’) and aperiodic (‘‘fricative’’) portions of stimuli, ranging from peas to peace, were varied in a 5 × 5 factorial design. Forced-choice identification judgments were elicited from two groups of native speakers of American English differing in dialect, and from two groups each of native speakers of French, Swedish, and Finnish differing in English-language experience. The results suggested that the non-native subjects used cues established for the perception of phonetic contrasts in their native language to identify fricatives as /s/ or /z/. Lengthening vowel duration increased /z/ judgments in all eight subject groups, although the effect was smaller for native speakers of French than for native speakers of the other languages. Shortening fricative duration, on the other hand, significantly decreased /z/ judgments only by the English and French subjects. It did not influence voicing judgments by the Swedish and Finnish subjects, even those who had lived for a year or more in an English-speaking environment. These findings raise the question of whether adults who learn a foreign language can acquire the ability to integrate multiple acoustic cues to a phonetic contrast which does not exist in their native language.
The instrument accuracy limit for objectively measuring the loudness rating of telephone systems
Authors: Irii Hiroshi , Kakehi Kazuhiko
Published: October 2005

This paper investigates a sensitivity measurement method for carbon transmitters and a calculation method for the loudness rating of a telephone system. The sensitivity varies depending on the artificial voice used for the measurement and the conditioning procedures. The most preferable methods for obtaining values which coincide with those in the subjective loudness rating test are discussed. With respect to the loudness calculation method, the algorithm, parameter values, ear leakage loss, and voice spectrum are discussed. As a result of these investigations, the deviation between the objective and subjective rating is found to be 0.7 dB for the various types of handset telephones when the measurement conditions are optimized. This deviation is considered to be the limit of measurement accuracy. The performance of currently developed objective measurement instruments is close to this limit. Considering the fluctuations accompanying repetitive subjective measurements, the objective rating corresponds satisfactorily with the subjective rating.
Zero rotation direction for acoustic wave propagation
Authors: Kumaraswamy K. , Krishnamurthy N.
Published: October 2005

Optically active crystalline α-quartz exhibits certain directions along which the optical gyrotropy vanishes. The possibilities of zero acoustic gyrotropy are studied along various directions in uniaxial and cubic crystal classes. The results indicate that zero acoustic rotation directions in α-quartz do not exist, while it is possible to find such directions in the cubic crystals.
Comments on ‘‘Sound diffraction for a spherical microphone’’ [J. Acoust. Soc. Am. 7
8, 266–267(1985)]
Authors: Cooper Duane H.
Published: October 2005

In a recent Letter to the Editor [J. Acoust. Soc. Am. 78, 266–267 (1985)], numerical errors have been found. Recalculated values are presented herewith.
The detection of liquids and viscoelastic substances trapped under solid surfaces
Authors: Jones H. W. , Kwan H. W. , Hayman T. , Yeatman E. M.
Published: October 2005

This paper describes theoretical and experimental aspects of a method of detecting, by acoustical means, a layer of oil trapped under ice. Previous work directed to this end is briefly reviewed. A new method of detection is outlined. The theory of mode conversion at the surface of a solid and a viscoelastic layer is discussed in detail. The use of the reflected and mode-converted acoustical signals for detection is described in some detail. Physical data collected for crude oil, sea water, and fresh water ice are presented. The theoretical predictions of acoustical mode conversion theory are compared with experimental results obtained from salt water ice and fresh water ice scenarios. A comment on the more general applicability of the method to other circumstances is given.
Factor inverse matched filtering
Authors: Birdsall Theodore G. , Metzger Kurt
Published: October 2005

Factor inverse matched filtering (FIMF) and factor inverse filtering (FIF) are signal processing techniques used to obtain desired signal responses. Both are especially useful procedures for ‘‘pulse-compression’’ processing and channel measurements. The theory is developed for a simple channel and known noise power spectral density so that comparison may be made with matched filtering. Expressions for the pulse-compression energy gain, nonflatness loss NFL, and total performance are derived. The NFL is useful in selecting the best among practical pulse-compression modulations, and with FIMF and FIF, has been used extensively since 1974 by the authors and their co-workers in underwater acoustic propagation measurements and ocean acoustic tomography.
Numerical studies of acoustic pulse scattering by baffled two-dimensional membranes
Authors: Kriegsmann G. A. , Scandrett C. L.
Published: October 2005

A new method for solving the scattering problem of acoustic pulses by baffled membranes is described. It is an adaptation of the finite difference technique which uses an ‘‘artificial’’ boundary condition to mimic an infinite region. The numerical method is used on several problems involving a plane compact pulse. It is also used on a time-harmonic pulse of infinite extent. This pulse generates a time-harmonic response as t→∞; this is proved in the Appendix. The numerical scheme is marched out in time until the transients have decayed away and a time-harmonic solution has been established. This ‘‘relaxation’’ scheme yields accurate solutions in a reasonable amount of time without requiring heavy or light fluid loading assumptions.
Determination of the resonance spectrum of elastic bodies via the use of short pulses and Fourier transform theory
Authors: de Billy M.
Published: October 2005

A method which permits a rapid determination of the resonance spectrum of submerged elastic cylindrical wires is described. A portion of the backscattering signal is selected by a gate, and the gated echo is Fourier-transformed into the frequency domain. Depending on the temporal position of the gate in comparison with the specular signal, either the form function (gate includes the rigid contribution) or the resonance spectrum (gate excludes the specular echo) was determined. According to the attenuation properties of the surface waves in cylindrical targets, the first (n, 1), or Rayleigh, resonances can be separated from the (n, l=2,3,...) resonances corresponding to the Whispering Gallery waves. The use of a broadband transducer is necessary in order to achieve a clear separation of specular and circumferential wave echoes.
An exact resonance decomposition of the acoustic transmission and reflection coefficients of a fluid layer
Authors: Fiorito R. , Madigosky W. , Überall H.
Published: October 2005

Previously, a resonance theory had been devised by us for the acoustic transmission (T) and reflection coefficient (R) of a fluid layer, or elastic plate imbedded in a fluid. This theory, based on the use of a ‘‘resonance approximation,’’ was restricted to the case of light fluid loading, or of a large impedance mismatch at the boundaries between the external fluid and the fluid layer or plate. In the present paper, the meromorphic function T (together with R) for a fluid layer is represented by a (Mittag–Leffler type) series expansion which not only directly exhibits resonance properties, but also furnishes the value of each resonance peak correctly, including the effect of the underlying tails of all other resonances. Being exact, this expansion is now applicable to the case of heavy fluid loading, or of a close impedance match between the external fluid and the layer.
Effective wave speeds in an SiC-particle-reinforced Al composite
Authors: Ledbetter H. M. , Datta S. K.
Published: October 2005

Plane-wave propagation in an SiC-particle-reinforced aluminum-alloy composite was studied. Considering the composite to possess orthotropic symmetry (nine independent elastic constants), by a pulse-echo method, nine independent ultrasonic velocities were measured. Measured elastic stiffnesses departed negatively up to 40% from a rule-of-mixture model. Using ensemble-average, scattered-plane-wave methods, the composite was modeled as SiC particles represented as prolate spheroids distributed randomly, both in position and in orientation. Wave speeds of plane waves, both longitudinal and shear, were calculated in the long-wavelength limit. These wave speeds lead to equations for the effective static bulk and shear moduli of the composite. Further, a nonhomogeneous particle distribution was considered. Wave-speed equations were derived for the case where the composite contains particle-free aluminum-alloy regions that were represented by oblate spheroids. The resulting anisotropic composite behaves transversely isotropicly. For all elastic constants, the model agrees with measurements, within a few percent.
Gas-filled spherical resonators: Theory and experiment
Authors: Moldover Michael R. , Mehl James B. , Greenspan Martin
Published: October 2005

Gas-filled spherical resonators are excellent tools for routine measurement of thermophysical properties. The radially symmetric gas resonances are nondegenerate and have high Q’s (typically 2000–10 000). Thus they can be used with very simple instrumentation to measure the speed of sound in a gas with an accuracy of 0.02%. We have made a detailed study of a prototype resonator filled with argon (0.1–1.0 MPa) at 300 K, with the objective of discovering those phenomena which must be understood to use gas-filled spherical resonators to measure the thermodynamic temperature and the universal gas constant R. The resonance frequencies fN and half-widths gN were measured for nine radially symmetric modes and nine triply-degenerate nonradial modes with a precision near 10−7 fN. The data were used to develop and test theoretical models for this geometrically simple oscillating system. The basic model treats the following phenomena exactly for the case of a geometrically perfect sphere: (1) the thermal boundary layer near the resonator wall, (2) the viscous boundary layer (for nonradial modes), (3) bulk dissipation, and (4) the coupling of shell motion and gas motion. In addition, the following phenomena are included in the model through the use of perturbation theory: (5) ducts through the shell, (6) imperfect resonator geometry, and (7) the seam where the two hemispheres comprising the shell are joined. Some estimates of the effects of (8) roughness of the interior of the shell have also been made. Much of the lower pressure fN and gN data can be explained by our model of these phenomena to within ±5×10−6 fN when a single parameter c0/(V0)1/3 is fit to a single resonance frequency at a single pressure. In this parameter, c0 is the ideal-gas speed of sound and V0 is the resonator volume. If this volume were known, the prototype resonator could be used to measure the speed of sound of a gas with an accuracy approaching ±0.0005%. Improvements in resonator design which will circumvent difficulties discovered in this work are expected to lead to much better agreement between theory and the measured fN and gN.
Transient radiation from axially symmetric sources
Authors: Guyomar Daniel , Powers John
Published: October 2005

A method is presented for the efficient calculation of radiated acoustic fields from a radially symmetric source in a rigid baffle excited by an arbitrary time excitation. The technique is a modal analysis based on the series expansion of the source velocity excitation in terms of either of two basis functions. Each mode is propagated by the technique with rapid convergence of the solution evident in 30 or less terms, allowing rapid and efficient computer-based solutions to be obtained. Several numerical field simulations are given.
Source depth distribution for uniform intensity in a surface sound channel
Authors: Weston David E.
Published: October 2005

A single acoustic source in a surface sound channel will produce an average acoustic intensity which varies with measurement depth, and the question is how to calculate the source concentration down a vertical array which will produce an intensity independent of depth. It is the long-range or range-averaged problem which is treated, using, initially, a high-frequency or energy flux approximation. The chosen approach works first from the uniform intensity back to the necessary depth distribution of quasimodes, and then from the quasimode distribution to the source distribution. We arrive at a universal curve specified in terms of elliptic integrals, which has a high concentration at the bottom of the duct. The same curve is reached using numerical methods. Comments cover wave theory effects and the efficiency of coupling. PACS numbers: 43.30.Bp, 43.30.Es
Accurate determination of object–image distance for planar objects in acoustical imaging
Authors: Narasimhan M. S. , Karthikeyan M. , Jegannathan S.
Published: October 2005

A new technique of processing the image data for accurately determining the object distance from the image plane, when a planar object is illuminated by a plane acoustic wave, is presented in this paper. Typical illustrations are presented, which establish the validity of the proposed technique.
Accuracy of distance measurement in the bat E
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s: Theoretical aspects and computer simulations
Authors: Menne Dieter , Hackbarth Heidi
Published: October 2005

Behavioral experiments of Simmons [J. Acoust. Soc. Am. 54, 157–173 (1973) and Science 204, 1336–1338 (1979)] on the ranging accuracy in the bat Eptesicus fuscus have led to far-reaching postulates on the existence of optimal and phase-conserving processing mechanisms in the bat. In this paper, the results of computer simulations of these experiments are presented. Two receiver types are investigated: the fully coherent cross-correlation receiver and the cross-correlation receiver with envelope processing (semicoherent). It is shown that Simmons’ experiments cannot be treated as a simple estimation of distance, but require at least two (range difference experiment; see Simmons, 1973) or four (range jitter experiment; see Simmons, 1979) echolocation sounds for one decision. The performance of the bat in both experiments is much worse than predicted for a coherent and a semicoherent receiver type. The bat’s accuracy in Simmons’ range difference experiment is at least 18 dB worse than predicted for an optimal receiver. The results of the jitter experiment cannot be interpreted in a simple way as proof that bats are able to evaluate phase information as in a fully coherent cross-correlation receiver.
Spectral analysis of numerical solutions to the Burgers–Korteweg–DeVries equation
Authors: Rao Kodali V.
Published: October 2005

Finite amplitude acoustic wave propagation through bubbly liquids is studied by using the Burgers–Korteweg–DeVries model equation. Numerical solutions are obtained using a pseudospectral method. Spectral analysis of the numerical solutions is performed to study the spectral energy transfer due to nonlinearity. Numerical solutions of the two limiting cases obtained by neglecting either the dissipation or dispersion term of the Burgers–Korteweg–DeVries equation are also analyzed. In nonlinear wave propagation, short waves are generated by long waves due to nonlinearity. In bubbly media, these short waves may undergo strong resonance absorption due to the presence of bubbles, even if other mechanisms of dissipation are negligible. The effect of such an absorption is simulated by applying a low-pass filter on the results obtained with the dissipation term neglected. The filter eliminates the short waves generated after each time step. It is shown that such resonance absorption corrections may be necessary for any quantitative comparisons of computed results with experiment.
Acoustic pulse scattering by baffled membranes
Authors: Kriegsmann Gregory A. , Norris Andrew N. , Reiss Edward L.
Published: October 2005

Asymptotic expansions as ε→0 that are uniformly valid in t are obtained for the membrane’s motion and the scattered acoustic pressure field. The small parameter ε is the density ratio of the acoustic fluid and the membrane. For simplicity of presentation, only plane, compact incident pulses are considered. The scattered field depends on the pulse’s structure. If it is a sufficiently narrow bandwidth pulse which contains none of the in vacuo natural frequencies of the membrane, then it is essentially reflected as though the baffled plane is completely rigid. However, if the pulse spectrum is sufficiently broad so that it contains one or more of the in vacuo natural frequencies of the membrane, an additional scattered field is produced. This scattered field insonifies distant observation points after the rigidly reflected pulse has arrived. It is the sum of slightly damped and oscillating outgoing spherical waves that represents the ‘‘decayed ringing’’ of the membrane. Application is given to the baffled circular membrane which is insonified by a normally incident pulse. Graphs of the membrane’s motion and the farfield acoustic pressure are given. They demonstrate the importance of the incident pulse width on the qualitative features of the response.
Intelligibility of vowels sung by a countertenor
Authors: Gottfried Terry L. , Chew Stephen L.
Published: October 2005

Ten American English vowels were sung in a /b/–vowel–/d/ consonantal context by a professional countertenor in full voice (at F0=130, 165, 220, 260, and 330 Hz) and in head voice (at F0=220, 260, 330, 440, and 520 Hz). Four identification tests were prepared using the entire syllable or the center 200-ms portion of either the full-voice tokens or the head-voice tokens. Listeners attempted to identify each vowel by circling the appropriate word on their answer sheets. Errors were more frequent when the vowels were sung at higher F0. In addition, removal of the consonantal context markedly increased identification errors for both the head-voice and full-voice conditions. Back vowels were misidentified significantly more often than front vowels. For equal F0 values, listeners were significantly more accurate in identifying the head-voice stimuli. Acoustical analysis suggests that the difference of intelligibility between head and full voice may have been due to the head voice having more energy in the first harmonic than the full voice.
Vibrotactile perception of suprasegmental features of speech: A comparison of single-channel and multichannel instruments
Authors: Carney Arlene Earley , Beachler Cindy R.
Published: October 2005

The recognition of three suprasegmental aspects of speech—the number of syllables in a word, the stress pattern of a word, and rising or falling intonation patterns—through a single-channel tactile device and through a 24-channel tactile vocoder, using two groups of normal-hearing subjects, was compared. All subjects received an initial pretest on three recognition tasks, one for each prosodic feature. Half the subjects from each group then received 12 h of training with feedback on the tasks and stimuli used in the pretest. All subjects received a post-test which contained physically different stimuli from those previously tested. Performance was significantly better on the syllable-number and syllabic stress tasks with the single-channel than with the multichannel device on both the pre- and post-tests; no difference was found for the intonation task. Performance on the post-test was poorer for all trained subjects compared to their final training results, suggesting that cues learned in training were not readily transferable to new stimuli, even those with similar prosodic characteristics. Overall, the results provide support for the notion that certain prosodic features of speech may be conveyed more readily when the waveform envelope is preserved.
Piano string excitation in the case of small hammer mass
Authors: Hall Donald E.
Published: October 2005

When a hammer of mass m strikes a string of mass M, it is dependent on the string for the force which will finally cause it to rebound. They remain in contact for a finite time, and this makes a general solution for the resulting string motion rather complicated. In the limit m≪M for a very stiff hammer the solution is relatively simple, but has some features that seem not to have been noted before. If the original hammer kinetic energy is E0, then 0.865 E0 is ultimately transferred to the string. Most interesting is that the normal modes with antinodes at the striking point receive only about two-thirds as much energy as certain other modes. Analytic expressions are also given for hammer masses which are finite but still small enough that the solution involves only the first reflection from the near end of the string. These apply to cases with m as large as 0.463 M, and show how the larger values of m affect the relative amplitude of the high-frequency modes. The mode energy spectrum level rolls off at 6 dB/oct above a mode number nmax∼0.73 M/m. Modes with either a node or an antinode at the striking point become missing modes for high frequencies.
Acoustic surface wave measurements on live bottlenose dolphins
Authors: Madigosky W. M. , Lee G. F. , Haun J. , Borkat F. , Kataoka R.
Published: October 2005

The surface wave velocity and absorption constant were determined on live bottlenose dolphins as a function of position, propagation direction, and frequency. A surface wave was propagated on the outer skin of a dolphin by an electromagnetic shaker driven by a noise source. Two miniature accelerometers were attached to the skin at a distance of 3.2 cm apart. The output signals from the accelerometers were analyzed by a dual-channel fast Fourier transform spectrum analyzer. The data acquisition was further automated by a minicomputer. The surface wave velocities were the highest below the dorsal fin area and the lowest at an area around the posterior insertion of the pectoral fin. Generally, the velocity and absorption constant were independent of the propagation direction (anterior, posterior, dorsal, and ventral) except near the dorsal fin. Over most of the regions measured, the surface wave velocity ranged from 4 to 14 m/s over the frequency range of 20 to 1000 Hz. The attenuation α (dB/m) was assumed to be α=Af, where A is the absorption constant and f is the frequency. The absorption constant was the highest around a line at the posterior insertion of the pectoral fin, 1.5 dB s/m, and the lowest just below the dorsal fin, 0.5 dB s/m.
Substrate thickness dependence of S
H wave propagation characteristics in rotated Y-cut X-propagation LiNbO3
Authors: Toda Kohji , Mizutani Koichi
Published: October 2005

Shear horizontal (SH) waves in rotated Y-cut X-propagation LiNbO3 plates are numerically analyzed. The phase velocity, displacement distribution, and electromechanical coupling constant are presented as a parameter of the product of the frequency and the substrate thickness, including the rotation angle dependences. Some experimental configurations on the numerical results are fairly good.
Comments on ‘‘Theory, ingenuity, and wishful wizardry in loudspeaker design—A half-century of progress?’’ [J. Acoust. Soc. Am. 7
7, 1303–1308 (1985)]
Authors: Villchur Edgar
Published: October 2005

Some of Augspurger’s statements about the acoustic-suspension speaker system are questioned. These concern the nonlinearity of the air spring in the enclosure, FM distortion, the definition of the acoustic-suspension principle as the use of a heavy cone, and the effect of the acoustic-suspension design on electroacoustic efficiency.
Reply to ‘‘Comments on ‘Harmonic and transient scattering from time varying obstacles’ ’’ [J. Acoust. Soc. Am. 7
6, 1527–1534 (1984)]
Authors: Censor D.
Published: October 2005

The present reply to the above comments by Piquette and Van Buren [J. Acoust. Soc. Am. 79, 179–180 (1986)] examines the legitimacy of the Doppler method for analysis of wave problems involving moving boundaries. Inasmuch as different results are predicted by Piquette and Van Buren, the ultimate test will have to be the experiment.
Auditory paradox based on fractal waveform
Authors: Schroeder Manfred R.
Published: October 2005

The synthesis of certain paradoxical acoustic waveforms is described that will sound lower when reproduced at higher speeds (and vice versa). Specifically, one such waveform, when recorded on magnetic tape, will sound a semitone lower (rather than an octave higher) when played back at twice the tape speed. The connection with fractal objects in geometry is illustrated.
Antireflective materials at ultrasound frequencies
Authors: Sajo Tibor
Published: October 2005

This paper describes the acoustic behavior of polyurethane base, microballoon filler composites for echo-reduction applications in water-filled tanks. The approach is similar to that of Corsaro et al. [J. Acoust. Soc. Am. 68, 655 (1980)] for silicon rubber, three-component anechoic systems with the additional study of off-normal incidence. Depending on the way the mixtures are cured, the surface echo reduction of the resulting composites can be improved by 13 dB at normal incidence. For the case of oblique incidence, the sound speed in these compounds is relatively close to that in water; this optimizes their surface echo reduction once the condition of impedance match is reached. Measurements reveal a front echo reduction better than 35 dB at 45° of incidence. A formula to estimate the ‘‘Net Echo Reduction’’ of an anechoic water-filled tank is also given.
Equilibrium shapes of acoustically levitated drops
Authors: Trinh Eugene H. , Hsu Chaur-Jian
Published: October 2005

The quantitative determination of the shape of liquid drops levitated in an ultrasonic standing wave has provided experimental data on the radiation pressure-induced deformations of freely suspended liquids. Within the limits of small deviations from the spherical shape and small drop diameter relative to the acoustic wavelength, an existing approximate theory yields a good agreement with experimental evidence. The data were obtained for millimeter and submillimeter drops levitated in air under 1 g, where g is the sea level gravitational acceleration.
Air absorption affected by Doppler shift
Authors: Makarewicz Rufin
Published: October 2005

It is the purpose of this paper to present the effect of air absorption on the intensity of sound produced by a moving point source, particularly the role of the Doppler effect in the absorption. It has been assumed that a nondirectional point source is moving along a straight line, with subsonic speed, in a homogeneous atmosphere. The investigation is based on a geometrical approach.
Speed of sound in standard air
Authors: Wong George S. K.
Published: October 2005

This paper describes the calculation of a new value for sound speed (c0=331.29 m s−1) in standard dry air at 0 °C and at a barometric pressure of 101.325 kPa. The maximum uncertainty is estimated to be approximately 200 ppm. The theory of the calculation is based on the equation of state, and includes the knowledge of γ/M which is derived from published theoretical and experimental thermodynamic data on the constituents of the standard atmosphere. Investigations which led to the general acceptance of the previous sound speed are examined, and there is good evidence to conclude that, in previous sound speed assessments, the maximum possible uncertainties were sufficient to encompass the above new sound speed. The variation of sound speed with carbon dioxide concentration and temperature is also discussed.
Wider-angle parabolic wave equation
Authors: Hill R. J.
Published: October 2005

A wider-angle parabolic wave equation (PE) previously obtained by factorization of the Helmholtz equation and interpretation of the square-root operator is derived by another method. The wider-angle capabilities of this PE are compared with the standard PE, using an analytically tractable case. The problem of using a PE in the nearfield is discussed.
Environmental correlates of pack ice noise
Authors: Makris Nicholas C. , Dyer Ira
Published: October 2005

Low-frequency ambient noise under pack ice of the central Arctic Ocean has long-term variations (periods greater than 1 h) which correlate highly with composite measures of stress applied to the ice by wind, current, and drift. These composites are the horizontal ice stress and the stress moment, and are derived from meteorological and oceanographic data observed simultaneously with the noise. Atmospheric cooling, a known high correlate of midfrequency noise under the ice, is not important at low frequencies.
A model for active elements in cochlear biomechanics
Authors: Neely S. T. , Kim D. O.
Published: October 2005

A linear, mathematical model of cochlear biomechanics is presented in this paper. In this model, active elements are essential for simulating the high sensitivity and sharp tuning characteristic of the mammalian cochlea. The active elements are intended to represent the motile action of outer hair cells; they are postulated to be mechanical force generators that are powered by electrochemical energy of the cochlear endolymph, controlled by the bending of outer hair cell stereocilia, and bidirectionally coupled to cochlear partition mechanics. The active elements are spatially distributed and function collectively as a cochlear amplifier. Excessive gain in the cochlear amplifier causes spontaneous oscillations and thereby generates spontaneous otoacoustic emissions.
Acoustic distortion in the ear canal. I. Cubic difference tones: Effects of acute noise injury
Authors: Schmiedt Richard A.
Published: October 2005

Acoustic emissions in the form of cubic difference tones (CDT’s), 2f1−f2, were measured in the ear canals of gerbils and cats. The state of the cochlea was manipulated by means of acute exposure to noise and was monitored with the aid of the whole-nerve response to tone pips. The resulting shifts in the levels of emissions generated by pairs of primary tones of equal intensity were then compared to the corresponding threshold shifts of the whole-nerve response across frequency. Data obtained from normal ears before injury indicate that the absolute thresholds of the whole-nerve responses across frequency are not necessarily good predictors of the absolute levels of CDT emissions generated by 70- and 80-dB SPL primaries. While high emission levels were often linked to low whole-nerve thresholds in pre-exposed ears, instances of animals with sensitive whole-nerve thresholds coupled with very weak emissions were also found. Conversely, animals with poor whole-nerve thresholds (shifted by up to 30 dB) could occasionally have high levels of emissions. After acute noise injury, however, the shifts of emission levels as a function of the center frequency of the primary-tone pair largely corresponded to the threshold shifts seen in the whole-nerve response. In other words, the temporary level shift of an acoustic emission largely reflected the acute change to a specific cochlear region associated with the primary frequencies.
Models of auditory masking: A molecular psychophysical approach
Authors: Gilkey Robert H. , Robinson Donald E.
Published: October 2005

Gilkey et al. [J. Acoust. Soc. Am. 78, 1207–1219 (1985)] measured hit proportions and false alarm proportions for detecting a 500-Hz tone at each of four starting phase angles in each of 25 reproducible noise samples. In the present paper, their results are modeled by fitting the general form of the electrical analog model of Jeffress [J. Acoust. Soc. Am. 48, 480–488 (1967)] to the diotic data. The best-fitting configurations of this model do not correspond to energy detectors or to envelope detectors. A detector composed of a 50-Hz-wide single-tuned filter, followed by a half-wave rectifier and an integrator with an integration time of 100 to 200 ms fits the data of all four subjects relatively well. Linear combinations of the outputs of several detectors that differ in center frequency or integration window provide even better fits to the data. These linear combinations assign negative weights to some frequencies or to some time intervals, suggesting that a subject’s decision is based on a comparison of information in different spectral or temporal portions of the stimulus.
Interaural correlation discrimination: II. Relation to binaural unmasking
Authors: Durlach N. I. , Gabriel K. J. , Colburn H. S. , Trahiotis C.
Published: October 2005

Many theoretical models of binaural interaction assume that sensitivity to interaural correlation underlies binaural unmasking. This paper explores the extent to which sensitivity to changes in interaural correlation implied by results from binaural detection experiments are consistent with sensitivity to changes in interaural correlation measured directly in correlation discrimination experiments. The vehicle for this exploration is a simplified model of the underlying processes assumed by many models of binaural unmasking for the detection of narrow-band signals in the presence of broadband noise. Consideration is given to psychometric function slopes, detection thresholds, bandwidth effects, duration effects, level effects, and interaural-parameter effects. Although many of the results obtained from our analysis are consistent with the notion that the cue in binaural detection tasks is a change in interaural correlation, some significant inconsistencies are noted.
Acoustic analysis and perception of vowels in stuttered speech
Authors: Howell Peter , Vause Louise
Published: October 2005

In stuttered repetitions of a syllable, the vowel that occurs often sounds like schwa even when schwa is not intended. In this article, acoustic analyses are reported which show that the spectral properties of stuttered vowels are similar to the following fluent vowel, so it would appear that the stutterers are articulating the vowel appropriately. Though spectral properties of the stuttered vowels are normal, others are unusual: The stuttered vowels are low in amplitude and short in duration. In two experiments, the effects of amplitude and duration on perception of these vowels are examined. It is shown that, if the amplitude of stuttered vowels is made normal and their duration is lengthened, they sound more like the intended vowels. These experiments lead to the conclusion that low amplitude and short duration are the factors that cause stuttered vowels to sound like schwa. This differs from the view of certain clinicians and theorists who contend that stutterers actually articulate SES’s when these are heard in stuttered speech. Implications for stuttering therapy are considered.
Wave propagation through a thin bubbly layer
Authors: Ng K. C. , Ting L.
Published: October 2005

The shielding effects of a thin bubbly layer submerged in pure liquid on the propagation of acoustic waves are analyzed. By using the method of matched asymptotics, conditions across the bubbly layer are derived. They are: (1) that the pressure is continuous and (2) that the jump of normal velocity is related to the temporal derivative of pressure times a parameter representing the bulk property of the bubbly layer. This parameter is the product of a small number and a large number. The former is the wavenumber times the integral of the gas volume fraction β across the layer and the latter is the ratio of the density times the square of the speed of sound for the liquid phase to that for the gas phase. When the thin bubbly layer is adjacent to a rigid surface, their combined effect is described by an impedance boundary condition.
Source range information loss in waveguides
Authors: Shang E. C. , Lawson L. M. , Palmer D. R.
Published: October 2005

In a previous study [E. C. Shang, C. S. Clay, and Y. Y. Wang, J. Acoust. Soc. Am. 78, 172 (1985)] a new method of passive source ranging in a layered waveguide was proposed. This paper investigates the reduction (loss) in range information due to phase fluctuations and to an inaccurate description of the environment (waveguide mismatch). The effects of phase fluctuations are investigated using a two-dimensional Gaussian distribution function. A numerical normal mode code is used to study the effects of waveguide mismatching. The loss in range information caused by incorrect descriptions of both the bottom sediment type and the sound speed profile in the water column is calculated. Examples are given for a water depth of 100 m and frequencies in the range from 100–500 Hz.
Surface-generated noise under low wind speed at kilohertz frequencies
Authors: Shang E. C. , Anderson V. C.
Published: October 2005

Some experimental observations of the ocean surface under low wind speed conditions, carried out with the high gain acoustic distribution array, ADA, indicate that bubbles may play an important role in the noise generating mechanism in this wind speed regime. One of the mechanisms discussed in the theory is that of bubble collapse in the surface turbulence layer as first proposed by Furduev [Atmos. Ocean. Phys. 2, 314 (1966)]. Under typical ocean conditions, low wind speeds, and the available bubble population data, the calculated noise level agrees well with experimental results, both in magnitude and in the shape of the spectrum. The spectrum has a peak in the frequency range of 100 to 1000 Hz and an ω−2 behavior at high frequencies. Several geophysical parameters could influence the noise generation. Local wind speed probably controls the population of bubbles, and swell-induced static pressure variations could play an important role in the critical turbulence pressure for bubble collapse. There seems to be further evidence that additional structure within the water, perhaps bubble density associated with different water masses, generates a patch type of distribution on the sea surface in the low wind speed situation.
Acoustic microscopy applied to measurements of sound absorption in liquid propane
Authors: Fossum J. O. , Cheeke J. D. N.
Published: October 2005

An acoustic lens has been used to study the relative change in sound attenuation for frequencies in the range 90–300 MHz between the normal freezing and boiling points of liquid propane. These are the first results for the lower part of this temperature range and they confirm the predominance of the viscous contribution to the attenuation.
An ultrasonic power meter
Authors: Ueha Sadayuki , Kuribayashi Minoru , Tsuda Yoneo , Mori Eiji , Hashimoto Yoshiki
Published: October 2005

A new ultrasonic power meter has been developed to measure the acoustic power flow of longitudinal vibration in a metallic rod as the product of particle velocity and vibration force. The technological difficulty that should be faced in measuring the vibration force by electrically obtaining the spatial differential coefficient of particle velocity has been overcome. The theory used here and the experimental verification of this method are also described.
A distribution based definition of impulse noise
Authors: Erdreich John
Published: October 2005

Determining when a worksite exposure should be considered impulsive is a problem which has complicated both research into mechanisms of auditory pathology and protection of the exposed worker. An ideal solution requires that a definition of impulsive noise be developed which is independent of specific characteristics such as duration and amplitude. As an alternative to duration independence, a fixed time window over which a statistic is calculated may also serve as a basis for classification. Additionally, selecting this window on the basis of TTS production in the ear provides a biological basis for the definition of impulsiveness. Classification of impulsiveness based on the sample kurtosis meets the requirements of a generally applicable impulse definition.
Super-resolution imaging of finite extent objects by estimating the hologram outside an aperture
Authors: Sasaki Osami , Yoshida Hirotoshi
Published: October 2005

A super-resolution imaging method is proposed which utilizes the finite extent of the object to estimate the hologram data outside the limited aperture from the hologram data detected at a small number of the points in the aperture by using the regularized singular value decomposition algorithm. The characteristics of this method are made clear by computer simulations, and the experiments show the usefulness of the method.
Numerical study of material properties of submerged elastic objects using resonance response
Authors: Werby M. F. , Tango G. J.
Published: October 2005

Scattering from many fluid-loaded elastic solid objects yields echo responses that are characteristic of rigid scatterers, with the exception of narrow resonance regions. These resonances are related to Rayleigh-type surface disturbances and thus are determined by the material properties of the scatterer. The purpose of this study is to predict resonances for several representative elastic materials to ascertain material properties that can be associated with resonance phenomena. This study was carried out using the T-matrix technique to determine backscattered form functions for spheroids composed of brass, aluminum, nickel, steel, molybdenum, and tungsten carbide. Either low density or low shear velocities have been determined to yield results that do not correspond to simple rigid backgrounds, though for all cases shear velocity alone practically determines the resonance location. A Rayleigh surface standing wave argument was found to be useful in deriving simple expressions that determine resonance locations as a function of shear velocity alone. These expressions compare well with numerical calculations.
Frequency division method for AE source characterization
Authors: Chang Chung , Sachse Wolfgang
Published: October 2005

This paper describes a new algorithm based on a frequency-division method by which a solution to the inverse source problem of acoustic emission can be obtained. The algorithm is applicable to cases in which the acoustic emission signal can be expressed as a bilinear equation involving weighted Green’s functions or its spatial derivatives, convolved with a common source–time function. Through division of the detected signals in the frequency domain, the common source–time function is eliminated and the ratios of the weighting constants can be recovered by solving a set of linear equations. Using these recovered ratios, the source–time function can be found from the signal at any receiver point. Application of this algorithm is made to process the signals simulating the formation of a microcrack in an elastic plate modeled with a second-order moment tensor. Dynamic information about the source is recovered by processing the signals at two receiver points. If four receivers are used, the second-order tensor can be recovered at each frequency of the recorded signals. Additional information about the source can be extracted by diagonalizing and rotating the recovered moment tensor. The effect of noise on the inversion scheme is also considered.
Excitation of surface waves of different modes at fluid–porous solid interface
Authors: Mayes Michael J. , Nagy Peter B. , Adler Laszlo , Bonner Brian P. , Streit Ron
Published: October 2005

The presence of ultrasonic surface waves of various modes on a fluid–porous solid interface is demonstrated and their velocities measured. The experimental technique (developed earlier by one of the authors for a fluid–isotropic solid interface) utilizes reflected broadband spectra from periodic surfaces. Three sharp minima corresponding to three mode-converted waves coupled to the porous solid are observed. The velocities of these ‘‘surface’’ waves are in qualitative agreement with theoretical predictions [S. Feng and D. L. Johnson, J. Acoust. Soc. Am. 74, 906 (1983) and 74, 915 (1983)] and are identified as pseudo Rayleigh, pseudo Stoneley, and true Stoneley waves.