bluuebunny/crossref_metadata_2025 huggingface dataset:
Scattering calculations using the characteristic rays of the coherence function
Authors: Beran M. J. , Whitman A. M. , Frankenthal S.
Published: October 2005

We use the two-scale expansion developed previously to determine the intensity variation in the neighborhood of caustics, to show how we may calculate the scattering of acoustic radiation in a random medium with a variable speed of sound profile. Equations are derived which show how the coherence function varies along the characteristic rays (identical to the rays of geometrical acoustics in the parabolic approximation). Conditions are given for simplifying the equations for high-frequency quasi-isotropic scattering. The problems that arise when the medium is highly anisotropic are discussed and an approximate solution is given. It is also shown how to calculate the intensity variation due to scattering in the neighborhood of a caustic.
An improved piezoelectric acoustic emission transducer
Authors: Proctor Thomas M.
Published: October 2005

A piezoelectric transducer has been designed and developed that has promise of being a high fidelity acoustic emission (AE) transducer [T. M. Proctor, Jr., J. Acoust. Soc. Am. Suppl. 1 68, S568 (1980)]. Small transducer contact area, elimination of acoustical interference effects associated with certain geometries, and redistribution of the arrival times of reflected signals originating from various elements of the transducer were the guiding criteria in the design. This transducer consists of a conical active element and an extended backing. The transducer’s performance has been compared to a line capacitance transducer using surface wave signals. These comparisons indicate an amplitude response which is flat within ±3 dB for the frequency range of 50 kHz to 1 MHz. The over-all displacement sensitivity is nominally 2×108 V/m. Factors that influence frequency response such as backing geometry and aperture size have been experimentally investigated and results are reported.
Monaural and binaural speech perception in reverberation for listeners of various ages
Authors: Nábělek Anna K. , Robinson Pauline K.
Published: October 2005

The Modified Rhyme Test (MRT) was processed through a room (volume 165 m3, reverberation time T = 0.4, 0.8, and 1.2 s). For both binaural and monaural earphone listening the tests were recorded with a manikin (Kemar) and equalization filters to compensate for the ear canal effect. Six groups of subjects, ten subjects each, had mean ages of 10, 27, 42, 54, 64, and 72 years and average hearing threshold levels, HTLs (for 0.5, 1, and 2 kHz) of 2.7, 5.6, 6.0, 10.9, 14.4, 17.5 dB, respectively. The individual scores for the MRT without reverberation were between 90% and 100% at 70 dB SPL. Children and the elderly required from 10 to 20 dB higher SPLs than young adults to obtain maximum scores. An analysis of variance showed that all the main effects: T, age, and monaural versus binaural listening were significant. The scores declined with T for all ages. The best scores were obtained by the young adults (27 year olds). The binaural scores were about 5% better than monaural scores. Factors contributing to the results and practical implications for amplification are discussed.
Wave propagation in nonhomogeneous thin elastic rods subjected to time-dependent velocity impact
Authors: Singh M. C. , Frydrychowicz W.
Published: October 2005

Response of a thin long nonhomogeneous elastic rod subjected to a time-dependent velocity impact is studied by the use of similarity transformations. Similarity representation of the original equation of motion and the associated conditions has been obtained in the form of an ordinary differential equation with variable coefficients and the corresponding boundary conditions. A general solution of the similarity representation is obtained in the form of series. Relations between the parameters of the problem for which the results hold have been obtained in the form of inequalities. The displacement and stress distribution in the rod is obtained for the admissible values of the parameters of the problem and the results are plotted for some of their discrete values. It is found that the stress is discontinuous at the wave front only in the special case of a homogeneous rod subjected to constant velocity impact; in all other cases the stress is found to be continuous at the wave front.
Scattering from inhomogeneities in layered structures
Authors: Karlsson Anders
Published: October 2005

In the present paper we give a general two-dimensional formalism for scattering in a multilayered medium with a finite inhomogeneity present. The formalism is based on the T matrix method, introduced by Waterman [J. Acoust. Soc. Am. 45, 1417 (1969)]. The formalism is developed in detail for the geometries consisting of one layer with an obstacle situated either inside or below the layer. More general geometries with an arbitrary number of layers are also discussed. Numerical results for the one-layer case are given. Extensions in several directions are indicated.
Scattering at a rough boundary—Extensions of the Kirchhoff approximation
Authors: Liszka E. G. , McCoy J. J.
Published: October 2005

A Helmholtz integral formula gives the acoustic field reflected from a rough surface, in terms of the values of the acoustic field and of its normal derivative at all points on the surface. For surface reflection problems in which one, or the other, of these surface field values are specified, we can make use of this formula to derive a boundary surface integral equation on the unspecified field values. Further, a series solution of this equation can be constructed by iteration, the zeroth-order term of the series being the result predicted by a Kirchhoff approximation. The nth-order iterate of this series requires an n-fold integration over the region of the rough surface, an integration that does not in general converge absolutely for unboundedly large surfaces. For a pressure release surface, we consider the first two iterates in detail and using stationary phase approximations replace the required integration by summations. In this way the source of the convergence difficulty is made clear and is demonstrated to result from the iteration procedure. We also demonstrate that the Kirchhoff approximation is not a complete high-frequency approximation and that multiple reflections and shadowings need be incorporated. These reflections and shadowings are associated with the stationary points of the higher order iterates in the series solution. Finally, we consider a proper manner for renormalizing the series solution, thereby removing the convergence difficulties.
Harmonics-to-noise ratio as an index of the degree of hoarseness
Authors: Yumoto Eiji , Gould Wilbur J. , Baer Thomas
Published: October 2005

Degree of hoarseness can be evaluated by judging the extent to which noise replaces the harmonic structure in the spectrogram of a sustained vowel. However, this visual method is subjective. The present study was undertaken to develop the harmonics-to-noise (H/N) ratio as an objective and quantitative evaluation of the degree of hoarseness. The computation is conceptually straightforward; 50 consecutive pitch periods of a sustained vowel /a/ are averaged; H is the energy of the averaged waveform, while N is the mean energy of the differences between the individual periods and the averaged waveform. Recordings of 42 normal voices and 41 samples with varying degrees of hoarseness were analyzed. Two experts rated the spectrogram of each voice sample, based on the amount of noise relative to that of the harmonic component. The results showed a highly significant agreement (the rank correlation coefficient = 0.849) between H/N calculations and the subjective evaluations of the spectrograms. The H/N ratio also proved useful in quantitatively assessing the results of treatment for hoarseness.
Effects of speaker accent on the performance of a speaker-independent, isolated-word recognizer
Authors: Gupta V. , Mermelstein P.
Published: October 2005

We report on an investigation of comparative performance of a speaker-independent, limited-vocabulary, isolated-word recognizer when trained and tested on (1) native English–Canadian speakers, and (2) French-Canadian speakers of English. Randomized 20-word vocabularies were recorded from 20 male and 20 female speakers of each group over individually dialed and locally switched telephone connections. Recognition performance with two clustering techniques was evaluated and a complete-link clustering algorithm is found to yield consistently better results. Although a recognition rate of 97% is attained when using ten templates/word for the native speaker group, the same rate drops to 93% for the foreign-accented speakers. For the linguistically homogeneous group, no significant increase in recognition rate is noted beyond four templates/word, whereas for the nonhomogeneous group, performance is still improving at ten templates/word. Additionally, the variability in recognition rate for individual speakers is significantly larger for the French Canadians. Although the above recognition rates may be acceptable for many applications, for even better performance it appears necessary to build into recognizers additional speech-specific knowledge such as differences in acceptable acoustic variation of phonetic segments.
A bootstrapping training technique for obtaining demisyllable reference patterns
Authors: Rabiner L. R. , Rosenberg A. E. , Wilpon J. G. , Zampini T. M.
Published: October 2005

The process of obtaining reference patterns for syllablelike units is tedious, error prone, and time consuming. As such, speech recognition systems based on such units are usually tested on only a single talker. In this paper we describe a procedure for using demisyllable reference patterns, excised from spoken utterances for one talker and automatically creating demisyllable reference patterns for a new talker. The procedure is based on dynamic time warping alignment of the spoken utterances (each containing the relevant demisyllable), and the assumption that the optimum warping path identifies the best matching demisyllable within the utterance. The automatic procedure has been used to create demisyllable reference patterns for two new talkers, each talking over a dialed-up telephone line (the original recordings were made over a high-quality microphone). Reference patterns were made for 100 isolated words from a given lexical specification of each word in terms of demisyllables in the inventory. Word recognition accuracies greater than 90% were obtained for both talkers on the 100-word vocabulary. In a second experiment, using a 1109-word vocabulary, recognition accuracies from reference patterns based on automatically extracted demisyllables were from 2%–5% worse than accuracies from reference patterns based on hand corrections applied to the demisyllables. These results show that the automatic demisyllable extraction technique provides a very good first pass set of demisyllables, and that combined with some manual corrections, provides a set of demisyllable patterns suitable for use in a recognition system.
On the plane-wave approximation of acoustic intensity
Authors: Beissner K.
Published: October 2005

The acoustic intensity is given by the product of acoustic pressure p and particle velocity v, but in the literature, expressions like p2/ρc or ρcv2 are often quoted. These are plane-wave approximations and are not in general valid. Assuming continuous-wave operation, the relations between the approximate formulas and the exact one are discussed in terms of the specific acoustic impedance. Further remarks deal with the vector character of the acoustic intensity and its connection with heat generation in the medium, as considered in a recent paper by Nyborg [J. Acoust. Soc. Am. 70, 310–312 (1981)].
Nature of the lateral wave effect on bottom loss measurements
Authors: Chin-Bing Stanley A. , Davis James A. , Evans Richard B.
Published: October 2005

The lateral wave is examined for the Sommerfeld model with respect to its effect on bottom loss measurement. Some inconsistencies between existing results are resolved and a numerical example is given.
Grüneisen numbers in hexagonal crystals
Authors: Nandanpawar Manik , Rajagopalan S.
Published: October 2005

Grüneisen numbers, which relate the change in the phonon mode frequency to the applied strain, can be estimated if all the second-order and third-order elastic moduli are known. Expressions for Grüneisen numbers are normally found in the literature for cubic and trigonal crystals only. In the present work, for the first time, expressions for Grüneisen numbers for both longitudinal and shear wave propagation along the (0 0 0 1) axis in hexagonal materials have been derived, considering 41 modes of pure elastic wave propagation affected by a longitudinal strain and 16 pure modes affected by a shear strain. The average of the Grüneisen numbers for longitudinal wave propagation along the hexagonal axis in magnesium is close to the Grüneisen constant determined from the thermal expansivities and specific heat, while the average for shear wave propagation along the c axis is zero, as expected. The expressions derived here can be used to estimate phonon viscosity losses in hexagonal materials.
Auditory perception of radio-frequency electromagnetic fields
Authors: Chou Chung-Kwang , Guy Arthur W. , Galambos Robert
Published: October 2005

Absorption of pulsed microwave energy can produce an auditory sensation in human beings with normal hearing. The phenomenon manifests itself as a clicking, buzzing, or hissing sound depending on the modulatory characteristics of the microwaves. While the energy absorbed (∠10 μJ/g) and the resulting increment of temperature (∠10−6 °C) per pulse at the threshold of perception are small, most investigators of the phenomenon believe that it is caused by thermoelastic expansion. That is, one hears sound because a miniscule wave of pressure is set up within the head and is detected at the cochlea when the absorbed microwave pulse is converted to thermal energy. In this paper, we review literature that describes psychological, behavioral, and physiological observations as well as physical measurements pertinent to the microwave-hearing phenomenon.
Resolution of the discrepancies between different physical optics solutions for rough surface scattering
Authors: Bahar Ezekiel
Published: October 2005

The analysis presented here resolves the discrepancies between the different high-frequency, physical optics expressions for the scattered field derived by several researchers in the field. On applying the divergence theorem (in two dimensions) the term associated with the edge effect is shown to vanish identically for all scatter directions. Thus it is also shown that the so-called edge effect which appears in earlier derivations of the physical optics solution for rough surface scattering is a result of premature truncation of the closed surface integral expression for the scattered fields. Therefore this term must be suppressed even when it is not very small compared to the scattered field in the off specular direction. Since the Kirchhoff approximations for the surface fields are used in the physical optics approach, it cannot account for wave diffraction by edges. The physical optics solution derived here for arbitrary source excitation is shown to satisfy reciprocity and realizability relationships in electromagnetic theory. The integrand in the integral expression for the scattered field is identified with the specific reflectance (per unit area) of the rough surface. Although the scalar acoustic problem is considered here in detail, the results are also applicable to electromagnetic scattering.
Comparison of sound scattering by rigid and elastic obstacles in water
Authors: Varadan V. K. , Varadan V. V. , Su J. H. , Pillai T. A. K.
Published: October 2005

Acoustic wave scattering by prolate and oblate spheroids and finite cylinders immersed in water is compared when rigid body and elastic boundary conditions, respectively, are satisfied at the fluid–scatterer interface. The frequency dependence of the scattered farfield is obtained for various angles of incidence for both types of boundary conditions using the null field or T-matrix approach. From our computations it is concluded that only for restricted materials properties of the scatterer, scattering geometry and scatterer shape, the scattering characteristics of an elastic obstacle, and a rigid obstacle of the same shape are comparable up to wavelengths comparable to the size of the obstacle.
Mean multipath intensity relation for sound propagation through a random ocean front
Authors: Neubert Jerome A.
Published: October 2005

By considering the stochastic nature of the phase fluctuations in the ocean, the conventional ray theory intensity relaxation was extended in an earlier paper [J. A. Neubert, J. Acoust. Soc. Am. 51, 310–322 (1972)] to permit consideration of partial coherence in multipath problems. Although this relation worked well in the open ocean [J. A. Neubert, J. Acoust. Soc. Am. 62, 326–334 (1977)], it proves to be incomplete for sound propagation through a random ocean front. By also considering the amplitude fluctuations, a mean multipath intensity relation (as well as its standard deviation σI) is found that takes into consideration the strong horizontal sound-speed gradients that occur in certain important ocean frontal regions.
Measurement of basilar membrane motion in the guinea pig using the Mössbauer technique
Authors: Sellick P. M. , Patuzzi R. , Johnstone B. M.
Published: October 2005

Basilar membrane motion was measured at the 16–19 kHz place of the guinea pig cochlea using the Mössbauer technique. The threshold of the gross cochlear action potential (CAP) evoked by pure-tone bursts was used as an indication of neural threshold. CAP threshold deteriorated progressively after the cochlea was opened and the Mössbauer source placed on the basilar membrane. A close relationship was found between the amplitude of basilar membrane motion at the source place frequency and CAP threshold. Basilar membrane velocity at CAP threshold SPL was about 0.04 mm/s over a 60-dB range of CAP threshold. Intensity functions for basilar membrane motion were linear for frequencies more than an octave below the source place frequency but demonstrated progressive saturation for frequencies greater than an octave below the CF. This nonlinear behavior was eliminated as the CAP threshold became less sensitive and was absent post mortem. Isovelocity curves at the 0.04 mm/s criterion were remarkably similar to frequency threshold curves from primary afferent fibers innervating a similar place on the basilar membrane. The isovelocity curve was a better fit than the isoamplitude curve suggesting that inner hair cells respond to basilar membrane velocity. As the CAP threshold deterioriated, the isovelocity curves lost sensitivity around the best frequency, whereas sensitivity to frequencies below 10 kHz remained constant even after the animal was killed. We suggest that most of the frequency response and nonlinear behavior of inner hair cells and afferent fibers may be found in basilar membrane motion.
Bioacoustics of the ear of the bushcricket H
e
m
i
s
a
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a (Sagenae)
Authors: Stephen R. O. , Bailey W. J.
Published: October 2005

The acoustics of the ear of the bushcricket, Hemisaga (Sagenae), have been examined using suprathreshold acoustic stimuli. By manipulating the acoustic inputs into the auditory system via the spiracle and tympanic slits, the frequency and directional characteristics of the structures of the ear have been measured. At the call carrier frequency of Hemisaga (?7.4 kHz) the ear behaves like a sharply tuned bandpass acoustic filter. The trachea appears to behave like the probe tube of a probe microphone. The structures which terminate the trachea, the tympana, slit cavities, and slits, are seen to behave like two Helmholtz resonators sharply tuned to the call carrier frequency. At the call carrier frequency the ear becomes highly directional; the directionality being determined by the slits alone. A new method of quantifying the neural response to suprathreshold acoustic stimuli is also discussed in detail.
The role of the gross spectral shape as a perceptual cue to place of articulation in initial stop consonants
Authors: Blumstein Sheila E. , Isaacs Ellyn , Mertus John
Published: October 2005

This series of studies explored the extent to which the gross shape of the onset spectrum is used by the listener for the identification of place of articulation in initial stop consonants. Synthetic stimuli were generated with onset formant frequencies appropriate to the syllables [ba bi bu da di du] and with the gross shape of the onset spectrum manipulated to be appropriate for either alveolar consonants or labial consonants. Stimuli were presented for identification and discrimination. In addition, adaptation effects of stimuli containing appropriate frequency and shape and incompatible frequency and shape were explored on a place-of-articulation onset continuum. Although identification performance was determined by onset frequency rather than gross shape of the spectrum, presentation of stimuli in which shape was inconsistent with frequency reduced identification performance. Further, subjects could discriminate stimuli which varied only in spectral shape. Finally, significantly less adaptation was found for a [da] onset with a labial spectrum shape than a [da] onset with an alveolar spectrum shape. These results suggest that although the invariant properties residing in the gross shape of the onset spectrum may serve as a classificatory framework for the phonetic dimensions of natural language, they may not provide the primary perceptual attributes for place of articulation in ongoing speech processing.
Normal hearing thresholds for clicks
Authors: Stapells David R. , Picton Terence W. , Smith Andrée D.
Published: October 2005

This paper evaluates the normal hearing thresholds for clicks and assesses the effects on these thresholds of varying the duration of the listening period and the presentation rate, polarity, and symmetry of the clicks. There were no significant changes in threshold as the listening period decreased from 2 s to 300 ms. There was, however, a 2.5 dB increase in threshold as the listening period decreased from 300 to 100 ms. Increasing stimulus presentation rate from 5 to 80/s decreased threshold 4.5 dB per tenfold change in rate. There were no significant differences in threshold between rarefaction and condensation clicks. The average threshold obtained from 40 normal young adults using 100-μs square-wave clicks presented through a TDH-49 earphone at 10/s was 36.4-dB peak SPL or 29.9-dB peak equivalent SPL. Neither peak SPL nor peak equivalent SPL measurements gave consistent thresholds for clicks with different degrees of symmetry. A root-mean-square measure of the pressure over the initial millisecond—SPL(1 ms)—gave a threshold of 25.6 dB. This SPL(1 ms) measure of threshold proved to be far more consistent for clicks with different degrees of symmetry than either the peak SPL or the peak equivalent SPL measures.
An approximation to the three-dimensional parabolic-equation method for acoustic propagation
Authors: Perkins John S. , Baer Ralph N.
Published: October 2005

We have reported previously [Ralph N. Baer, J. Acoust. Soc. Am. 69, 70–75 (1981)] on an algorithm, based on the parabolic approximation to the reduced wave equation, for the propagation of sound in three dimensions in the ocean. We present here a simpler algorithm: solve N two-dimensional problems and combine the results to form an approximate three-dimensional solution. Analytic and numerical results show that this N×2D approach is an excellent approximation to the original algorithm for realistic ocean environments, even those where fronts and eddies are present, provided redirection of energy in azimuth due to boundary interaction is not important. We compare the two computer models based on these algorithms for several test cases by considering how they distribute energy spatially, and by simulating the performance of a hypothetical horizontal array of hydrophones placed in the calculated complex-valued acoustic fields. In an example of propagation through a large and strong ocean eddy, the N×2D method predicts intensities and array performance parameters (such as array signal gain) which are typically within 8% of the values from the full 3D algorithm. In another example, with a large linear cross-range gradient on the index of refraction, the N×2D and 3D solutions are essentially identical out to a range of 120 km. The new method has made it practical to consider higher source frequencies and has reduced the substantial computer time of the three-dimensional program.
The k-space formulation of the scattering problem in the time domain
Authors: Bojarski Norbert N.
Published: October 2005

The arbitrary direct scattering problem is solved numerically in closed form in the time domain and spatial Fourier transform space. This solution consists of casting the general basic global laws (i.e., the second-order partial differential wave equation or its integral representation) as a local algebraic equation in the spatial Fourier transform space, and leaving the specific local constitutive equations (i.e., the algebraic boundary conditions, which specify a given structure, which are conventionally imposed on the differential or integral representation of the general basic global wave equation) as a local algebraic equation in real space, thereby reducing the scattering problem to a statement of two simultaneous local algebraic equations in two unknowns (the fields and the induced sources) in two spaces connected by the spatial Fourier transform. A temporally local representation in both spaces is obtained with the aid of an introduced auxiliary field and two propagators. By virtue of causality, a numerically efficient closed form solution to this set of equations is obtained that utilizes the fast Fourier transform algorithm as the transformations between the two spaces. By virtue of the numerically efficient fast Fourier transform algorithm and the local algebraic representations, the number of required complex multiply-add operations and storage allocation is of the order of N log2 N and N per temporal discretization, respectively (where N is the number of spatial cells into which the scattering problem is descretized). It is shown that the solution is only of the order of log2 N slower than an ideal solution. The solution is thus practical for very large one-, two-, and three-dimensional scattering problems. Numerico-experimental results for a variety of refrective index profiles, including perfect reflectors, are presented, thus verifying the presented algorithm.
Reflection and transmission of bounded sound beams on half-spaces and through plates
Authors: Claeys J. M. , Leroy O.
Published: October 2005

Reflection of bounded sound beams incident from a liquid on solid half-spaces or plates and transmission through plates are described using one new mathematical model. Since the exact expressions for reflection and transmission coefficients are used, reflected and transmitted beam profiles can be predicted at any angle of incidence. Using a simple representation by inhomogeneous infinite waves, it is possible to obtain analytical expressions for reflected and transmitted beams, whatever the form of the incident profile may be. As the bounded beam is built up by inhomogeneous waves, all propagating in the same direction, it can be easily interpreted and it is possible to detect those parts that are generating surface waves.
Frequency-dependent angle scattering of ultrasound by liver
Authors: Waag R. C. , Lee P. P. K. , Persson H. W. , Schenk E. A. , Gramiak R.
Published: October 2005

Ultrasonic scattering by one specimen of normal pig liver and two specimens of abnormal human liver has been measured as a function of angle and frequency at each angular position of transmit and receive transducers which were rotated in equal and opposite directions about the axis of a cylindrically shaped tissue sample. Mean data values were determined by averaging points at like frequencies and angular positions in scans made at intervals along the axis of the specimen. Sections of the specimens were obtained throughout its length and stained to emphasize structures containing collagen and connective tissue shown by acoustic microscopy to produce sound speed variations which are known to cause scattering. Using the stained sections as diffraction screens, calculations of scattering were carried out via Fourier transforms on a scale comparable to that in the acoustic studies for comparison with the acoustic data. In all specimens studied, mean acoustic scattering exhibited a general decrease in level with increasing scattering angle. The rate of decrease in acoustic scattering with angle agreed qualitatively with the calculations of average angular falloff of scattering by the stained sections. Lower rates of decrease were observed in tissues with more closely spaced collagen containing structures. Although the data derived from the few substantially different specimens studied is not intended to be representative of all liver, the results show a qualitative correspondence between acoustic scattering and visual appearance which depends on tissue components and their arrangement.
Speaker-independent isolated word recognition using a 129-word airline vocabulary
Authors: Wilpon J. G. , Rabiner L. R. , Bergh A.
Published: October 2005

Previous work at Bell Laboratories has shown that a reliable set of word reference templates for a speech recognition system can be obtained using sophisticated statistical clustering techniques. These studies have used a 39-word alpha-digit vocabulary and a 54-word vocabulary of computer terms. In this paper the clustering procedures, developed previously, are extended to create reference tokens for a 129-word vocabulary of airline reservation terms. Instead of using a single, casually obtained token of each word by each of 100 talkers for the clustering procedure, each talker used the robust training procedure of Rabiner and Wilpon to provide a robust token of each vocabulary word. The effect on the clustering is to reduce the number of outlier tokens and to provide more robust clusters. Recognition tests using 20 new talkers yielded recognition accuracies of between 80%–97%. These accuracies are comparable to those obtained in an earlier study on the same vocabulary with speaker trained reference patterns.
Measures of intensity discrimination
Authors: Grantham D. Wesley , Yost William A.
Published: October 2005

Several different measures have been employed in the literature to describe performance by human observers in intensity discrimination tasks. These measures include the difference limen (DL) or ’’ΔI in dB,’’ the Weber fraction (ΔI/I), and signal-to-masker ratio (Ps/Pm). This article describes the mathematical relationship among these measures for conditions in which masker and signal are (1) sinusoids of the same frequency; (2) sinusoids of different frequencies; and (3) noise waveforms. We provide a table which contains values of each of these measures, describing equivalent performance over the typical range obtained in most intensity discrimination experiments. We express some cautions that should be observed in choosing and reporting particular measures of intensity discrimination.
Calculations of the sound transmission over theater seats and methods for its improvement in the low-frequency range
Authors: Ando Yoichi , Takaishi Masako , Tada Koji
Published: October 2005

It is well known that sound waves propagating over rows of theater seats are subject to selective attenuation at low frequencies. Theoretical calculations of the sound transmission were carried out for various boundary conditions of the seat and floor combination. The results show that the attenuation always appears in the frequency range of 50–200 Hz and that it can be reduced by absorbing floor surfaces. In order to realize an absorbing floor in the required frequency range, effects of installing slit resonators under the floor are examined.
Attenuation of low-frequency sound in the Northeast Pacific Ocean
Authors: Chow R. K. , Turner R. G.
Published: October 2005

Long-range propagation losses were measured at frequencies from 0.025 to 0.8 kHz to the north and south of a receiver at 46 °N, 143°30′W in the Northeast Pacific. To the south of the station, the attenuation losses experienced a pronounced minimum near 50 Hz and approached the one-half Thorp value at 0.8 kHz. An examination of the behavior of the attenuation coefficient as a function of range indicated that a range of at least 700 km would be required to make meaningful measurements of attenuation in this area. To the north of the receiving station, focusing of the sound due to a rapidly shallowing sound channel prevented reliable measurement of the attenuation coefficient at any range.
A transport-theoretic analysis of pulse propagation through ocean sediments
Authors: Besieris Ioannis M. , Kohler Werner E. , Freese Herbert
Published: October 2005

The reflection of pulsed acoustic plane waves from ocean sedimentary layers is studied using a stochastic transport theory originally introduced by Barabanenkov et al. [Izv. Vyssh. Uchebn. Zaved., Radiofiz 15, 1852 (1972)]. The sediments are assumed to be a random medium in which the density and sound speed undergo small, highly laminated (pancakelike) fluctuations. Although the problem is formulated in a general context, the predictions of the theory are fully evaluated only in the special case of normal incidence and no refracting profile. However, even with these approximations, some reasonable qualitative agreement of theoretical predictions with measured data is achieved.
On sound scattering and attenuation in suspensions, with marine applications
Authors: Hay Alex E. , Burling R. W.
Published: October 2005

The theory of sound scattering and attenuation by a mobile, elastic sphere in a viscous, heat-conducting fluid is formulated in terms of phase angles for the partial scattered waves. The solution reduces in the appropriate limit to that for the inviscid, nonconducting case. Specializing to the long-wavelength limit, an important case in marine acoustic remote sensing applications, expressions are obtained for the sound pressure amplitude of the scattered wave including the effects of viscous and thermal absorption at the fluid–particle interface. Furthermore, an expression is obtained for the ratio of thermal to viscous absorption and it is shown that this ratio is small for particles with bulk densities greater than 1.3–1.7 g cm−3 suspended in water, depending upon the thermal and elastic properties of the solid, and provided the acoustic frequency is such that the skin depths of the thermal and viscous waves are less than the particle radius.
Use of the towship for assessing towed-array performance and analyzing data quality
Authors: Wagstaff R. A. , Berrou J. L. , Cotaras F. D.
Published: October 2005

A series of relatively simple tests are presented and discussed, which used in conjunction with the noise received from the towship, can be used in real time to assess the performance of a towed array and the quality of the acoustic data. One test constitutes a simple, yet thorough, relative amplitude calibration of the sonar system. Examples from actual measurement situations are given to illustrate the utility of these tests in indicating the existence of problems and providing clues to their sources. Results suggest that problems which affect array performance and degrade data quality occur more often than might be expected. Once the problem is corrected, however, measurements can ofttimes be carried out with a near-perfect system. Measured side-lobe suppression levels in excess of 40 dB and in some cases in excess of 50 dB are not uncommon.
The scattering of ultrasonic waves by polycrystals
Authors: Hirsekorn Sigrun
Published: October 2005

An ultrasonic scattering theory is presented which allows one to calculate the scattering coefficients and velocities of plane longitudinal and transverse waves in polycrystals as a function of the wavenumber k times grain radius a without limitation to the Rayleigh region. The theory includes mode conversion and multiple scattering and can be used to describe ultrasonic propagation in polycrystals with randomly orientated grains as well as in those with preferred grain orientation. The calculation was done for compressional waves in polycrystals of cubic symmetry with randomly orientated grains in second-order perturbation theory using the assumption that the changes in the elastic constants and in the density of the materials from grain to grain are small. The asymptotic values at low ka (Rayleigh scattering) are exactly the same as the well-known results from Bhatia and Moore. Numerical calculations are carried out for some examples.
New optical method for recording lip and jaw movements
Authors: Sonoda Yorinobu , Wanishi Satoshi
Published: October 2005

A new optical recording system for labial and mandibular movements during speech is presented. An optical position sensor is used to detect the positions of small infrared LEDs attached to the lips and to a rigid wire fixed to the mandibular teeth. The system allows continuous data collection of eight points at a sampling period of 4 ms with a high accuracy and a very fast response. Some preliminary data are given for one subject.
Loudness adaptation induced by an intermittent tone
Authors: Botte Marie-Claire , Canévet Georges , Scharf Bertram
Published: October 2005

The loudness of a continuous 1000-Hz tone at 60 dB SPL was measured in the presence of an intermittent tone in the contralateral ear. Over 70 observers participated in a series of eight experiments. The method of successive magnitude estimation showed that the intermittent tone causes the steady tone to diminish in loudness within 2 or 3 min by 40% to 60%. The amount of this induced loudness adaptation depends weakly upon the presentation rate, frequency, and level of the contralateral tone. Loudness reduction of the steady tone is coupled with loudness enhancement of the intermittent tone in the opposite ear. Induced loudness adaptation was also revealed by interaural and cross-modality matching. Induced loudness adaptation depends strongly on interaural interaction and is probably related to lateralization and interaural funneling of loudness. Adaptation induced by an intermittent tone stands in marked contrast to the near absence of loudness adaptation, except near threshold, when a continuous sound is presented alone.
Responses of primary auditory fibers to brief tone bursts
Authors: Geisler C. Daniel , Sinex Donal G.
Published: October 2005

Responses of primary auditory fibers to short triangularly modulated bursts of tone were obtained in the anesthetized cat. Based on discharge rate alone, the characteristics of the ’’response areas’’ obtained with these tone bursts were found to depend on the best frequency of the fiber. For a fiber with low best frequency (below 1 kHz), tones of greater than 10-ms duration had to be presented in order for the frequency resolution of the neuron to be as good as it was for long tones. For fibers with high best frequencies (above 10 kHz), tones of 2 or even 1 ms caused responses that were nearly as frequency selective as those obtained with long tones. A linear minimum-phase model based on the steady-state frequency selectivity of the fibers has been developed and shows generally comparable responses, but with some interesting exceptions. Synchronization of discharges to the waveform of the low-frequency tone bursts was measured and also shown to be generally compatible with the minimum-phase model. Trapezoidally modulated tone bursts were also used.
Broadband and narrow-band signal-to-interference ratio expressions for a doubly spread target
Authors: Ziomek Lawrence J. , Sibul Leon H.
Published: October 2005

Signal-to-interference ratio (SIR) expressions for a doubly spread target are derived for both broadband and narrow-band transmit signals. For broadband signals, the SIR is dependent upon target and reverberation two-frequency correlation functions and upon the transmit and processing waveforms. For wide-sense stationary uncorrelated spreading (WSSUS) communication channels (which implies narrow-band transmissions), the SIR is dependent upon target and reverberation scattering functions and the cross-ambiguity function of the transmit and processing waveforms. Volume reverberation and target two-frequency correlation functions and scattering functions are derived. Volume reverberation is modeled as the spatially uncorrelated scattered field from randomly distributed point scatterers in deterministic plus random translational motion. A single scattering approximation is used and frequency-dependent directivity functions and attenuation due to absorption are included. A probability density function of random Doppler shift due to the random motion of the scatterers is also derived. Computer plots of the density function are presented as a function of the standard deviation of the random motion. The target is modeled as a linear array of discrete highlights in deterministic translational motion. Example scattering function calculations are presented. The volume reverberation scattering function predicts Doppler spreading as a function of both beam steering angle and random motion of the scatterers. The target scattering function also predicts a spread in Doppler values. Both scattering functions predict time spread and/or contraction as a function of Doppler spread.
Electromechanical properties of (Pb, Ln) (Ti, Mn) O3 ceramics (Ln = rare earths)
Authors: Takeuchi Hiroshi , Jyomura Shigeru , Yamamoto Etsuji , Ito Yukio
Published: October 2005

Electromechanical properties of PbTiO3 ceramics modified by the partial substitution of rare earths for Pb, particularly, (Pb, Ln) (Ti, Mn) O3 (Ln = La, Pr, Nd, Sm, or Gd) ceramics, are examined. It is found that the Sm substitution for Pb dramatically increases the ratio of electromechanical coupling factor of the thickness dilatational mode to that of the planar extensional mode. Extensive studies of the resonant properties of rectangular strip resonators make it clear that the Sm-substituted PbTiO3 ceramics are very useful for high-frequency array transducer applications. It is also shown that the pulse responses of array transducers can be improved using Sm substituted PbTiO3 ceramics instead of the other PbTiO3 ceramics studied here.
Regularization of Marchenko’s integral equation by total least squares
Authors: Silvia Manuel T. , Tacker Edgar C.
Published: October 2005

Succinctly, the inverse scattering problem is to infer the shape, size, and constitutive properties of an object from scattering measurements which result from either seismic, acoustic, or electromagnetic probes. Under ideal conditions, theoretical solutions exist. However, when the scattering measurements are noisy, as is the case in practical scattering experiments, direct application of the classical inverse scattering solutions results in numerically unstable algorithms. In this paper, we discuss an optimization technique called total least squares, which provides a regularization to the one-dimensional inverse scattering problem. Specifically, we show how to use multiple data sets in a Marchenko-type inversion scheme and how the theory of total least squares introduces an adaptive spectral balancing parameter which explicitly depends on the scattering data. This is in strong contradistinction to ordinary least squares techniques which utilize nonexplicit and nonadaptive spectral balancing parameters, generally derived by ad hoc considerations.
Reliability of social survey data on noise effects
Authors: Hall Fred L. , Taylor S. Martin
Published: October 2005

The results of household interviews provide essential data for the formulation of noise control policies. The few previous studies which have investigated the reliability of such data have yielded low test–retest correlations for measures of annoyance at road traffic noise. This paper complements those previous studies by investigating four related topics: the equivalence of three commonly used annoyance scales; the test–retest reliability of two such scales, for aircraft and overall noise as well as for road traffic noise; the repeatability of measures of average response, such as percent highly annoyed; and the effect on reliability estimates of the range of noise levels included in a survey. The data are from a sample of 212 persons in the vicinity of Toronto International Airport, who were interviewed one year apart, in 1978 and 1979. The sample was stratified by both aircraft and road traffic noise levels. The results show that three commonly used annoyance scales are acceptably equivalent (a composite index comprised of the three has reliability of α = 0.85), and that the effect on the reliability of the range of noise levels included appears to be minimal. The test–retest results are similar to previous findings, suggesting that instability of attitudes toward noise, as well as other sources of measurement error, affect such estimates, and reduce retest estimate of reliability. Much better retest reliability (r≳0.90) is found for measures of average group response such as the percent highly annoyed than for individual level response measures.
Comments on K. D. Kryter’s paper, ’’Community annoyance from aircraft and ground vehicle noise’’
Authors: Schultz Theodore J.
Published: October 2005

This paper presents a critique of K. D. Kryter’s paper, ’’Community Annoyance from Aircraft and Ground Vehicle Noise’’ [J. Acoust. Soc. Am. 72, xxx–xxx (1982)] in which he purports to show that an earlier paper of Schultz, ’’Synthesis of social surveys on noise annoyance’’ [J. Acoust. Soc. Am. 64, 377–405 (1978)], significantly underestimates the annoyance associated with aircraft noise, and underestimates that due to surface traffic noise. While the earlier Schultz paper may not be entirely correct, a careful study of Kryter’s new analysis suggests that his conclusions are considerably more dubious than he regards those of Schultz.
Localization of paired sound sources in cats: Effects of variable arrival times
Authors: Cranford Jerry L.
Published: October 2005

Six adult cats were trained to perform sound-localization tasks involving either single or paired sound sources. The behavioral response consisted of the cat releasing the left of two foot pedals when sound was perceived to the left of midline, and to release the right pedal, when the sound occurred on the right. In sessions with paired sounds, the effects of varying the time interval between the arrival of clicks from the left and right speakers were examined. The intervals used were 0.0, 0.2, 0.3, 0.5, 1.0, 2.0, 3.0, 5.0, 7.0, and 9.0 ms. For the group as a whole, the optimal delay interval for most accurate localization fell within the range from 0.5 to 2.0 ms.
Calibration of miniature ultrasonic receivers using a planar scanning technique
Authors: Herman Bruce A. , Harris Gerald R.
Published: October 2005

This paper discusses a method currently used to calibrate miniature ultrasonic receivers in the 1- to 10-MHz frequency range. The method compares the power radiated by a source transducer to the integrated intensity obtained by scanning the receiver across the ultrasound field in a series of linear parallel lines. Sources of error are presented and theoretical models and experimental data are analyzed to estimate the maximum uncertainty associated with this technique, as used by the Bureau of Radiological Health. Our calculations estimate the accuracy of the intensity calibration constants determined to be within +17%, −23% of the true value. With refinement of this technique an uncertainty within +14%, −13% should be achievable.