bluuebunny/crossref_metadata_2025 huggingface dataset:
Formulae for estimation of undersea noise spectra
Authors: Merklinger H. M.
Published: October 2005

This paper describes simple formulae which may be used to describe underwater ambient noise spectra. Two noise sources are considered: shipping and wind-generated sea surface agitation. Shipping noise is defined at input by the estimated noise level at 60 Hz. Wind-generated noise is defined by wind speed. Spectral shapes are based largely on the 1962 paper of Wenz though several other references are considered. The formulae may be evaluated on a programmable hand calculator.
Fundamental frequency as a cue to postvocalic consonantal voicing: Some data from perception and production
Authors: Gruenenfelder Thomas M.
Published: October 2005

Several recent studies by Lehiste have reported that changes in fundamental frequency (F0) can serve as a cue to perceived vowel length and, furthermore, the perceived lengthening of the vowel can influence perception of the voicing feature of stop constants in final position. In Experiment I, we replicated Lehiste's basic result for stops in final position. Stimuli of intermediate vowel duration from a “bat-bad” continuum were more often perceived as voiced (“bad”) when F0 was falling than when F0 was monotone. In Experiment II, we found the same effect for fricatives in a synthesized “cease-seize” continuum. In Experiment III, we examined the F0 contours produced by a single talker before post-vocalic stop consonants and fricatives in natural speech for minimal pairs of words differing on voicing. The amount of change of F0 of the vowel was no greater before than voiced than voiceless consonants though rate of change was greater before voiceless consonants due to the shorter vowel duration. Our results indicate that, although F0 contour is capable of functioning as a cue to voicing of a postvocalic consonant in perception, its generality as a perceptual cue to voicing may be extremely limited given that the distinction is not reliably made in speech production as well. [Supported by NIMH and NINCDS.]
On discrimination of relative onset times
Authors: Bensen P. J. , Clack T. D.
Published: October 2005

Voice-onset time is a relevant cue to the voice-voiceless distinction in synthetic initial stop consonant perception. Studies with infants, adults, and animals have all shown the importance of the relative onset times between components of speech signals. Such unanimity could indicate the operation of a basic perceptual mechanism as suggested by Pisoni [J. Acoust. Soc. Am. 61, 1352–1361 (1977)]. He used “speech-like” stimuli consisting of paired tone (500:1500 Hz) differing in onset times, and found that some listeners produce ABX discriminations with peaks in the vicinity of ±20 ms lead-lag intervals. The purpose of this study is exploration of other frequency:intensity combinations, e.g., the second and third harmonics of 250, 500, and 1000 Hz varied over the 50-to-90 dB SPL range. The results are discussed with respect to masking, and the discriminability of differences in temporal order of high-frequency versus lower-frequency components.
The effect of the human torso, head, and pinna on the azimuthal directivity and on the median plane vertical directivity
Authors: Kuhn George F.
Published: October 2005

The azimuthal directivity and the vertical directivity in the median plane were measured at the coupler microphone of an electroacoustic manikin, comprised of a torso, head, and six different pinnae molded from live subjects. The experimental conditions separated the directional effects of the torso, head, and pinna. Below 2.5 kHz the vertical directivity is primarily governed by reflections from the torso. At 5.0 kHz and higher frequencies, the vertical directivity, with the exception of an approximate ±30° sector for sound incident from below. is primarily governed by higher order acoustic modes in the pinna. These results agree well with published studies of subjective localization in the median plane. For frequencies below 2.5 kHz the azimuthal directivity can be predicted approximately on the basis of a point receiver on a rigid sphere, with an appropriate correction for torso reflections. For higher frequencies the azimuthal directivity is shaped by the coupling of higher order acoustic modes in the pinna to the ear canal. Interpinna differences can be resolved on the basis of transverse acoustic modes, cutoff frequencies, and pinna size. [Portions of this work were done at the National Bureau of Standards, Washington, DC 20234.]
A model wavevector-frequency spectrum of turbulent-boundary-layer wall pressure
Authors: Chase David M.
Published: October 2005

An explicit wavevector-frequency spectrum of wall pressure is formulated for potential validity throughout the incompressive, inviscid domain. It is characterized as space-time isotropic in a mean convected frame, wavenumber-quadratic and streamwise-peaked at low wavenumbers, and scale-independent except at effective wavenumbers below a cutoff of the order of reciprocal boundary-layer thickness. The model is suggested on the basis of (1) geometrically similar boundary-layer waves with phase-convection speed nearly independent of wall distance and with factorable angle dependence (following Kronauer and Morrison), (2) boundary-layer thickness as the upper limit on wall distance for appreciable fluctuating-velocity correlation, (3) fluctuating-velocity correlations in the mean convected frame modeled as similarly affected by planar separation ζ and time delay ∼ζ/v, in quadrature. The streamwise-wavenumber-quadratic part of the model spectrum, identified with mean shear, largely reproduces the decrease of phase-convection speed and of frequency spectrum of wall pressure at low frequencies and the characteristic contours of the spatial correlation at zero time delay. With admixture of an isotropic part, most measured properties dominated by the convective ridge are successfully reproduced. Still, the length scale indicated by the contours of spatial correlation exceeds that indicated by the maximum of the frequency spectrum. The model spectrum at low wavenumbers likewise is consistent with that measured by Jameson and not at variance with other measurements if these yield only upper bounds. [Work sponsored by ONR 222.]
The effects of scattering and interaction on the beam pattern of a system of two parallel cylinders and a planar baffle
Authors: Gustafson Harry L. , Stepanishen Peter R.
Published: October 2005

An investigation of the scattering and interaction effects on the receive beam pattern of a pair of parallel cylinders and a baffle will be presented. An incident plane wave is assumed and the effects of the baffle are included using classical image theory. The cylinders and baffle are considered to be infinite in extent and idealized boundary conditions are considered. An eigenfunction approach which was originally developed for electromagnetics [V. Twersky, J. Appl. Phys. 23, 407–414, 1952] and then adapted to acoustics [J. W. Young and J. C. Bertrand, J. Acoust. Soc. Am. 60, 1265–1269, 1976] is utilized to solve the multibody acoustic scattering and interaction problem. In addition, two simpler approaches are investigated. Numerical results will be presented for all three approaches, and the useful range for utilization of the simpler solutions will be shown.
Music perception
Authors: Deutsch Diana
Published: October 2005

The state of knowledge in several areas of music perception will be reviewed. Topics to be covered include principles of organization and grouping, tonal shape analyzing mechanisms, rhythm, and tempo, the role of memory, and the perception of instrumental timbre. The field as a whole is currently undergoing rapid expansion. This is due in large part to recent technological advances which have facilitated the generation of complex auditory stimuli with precisely controlled parameters. Given the developing interest among scientists, music theorists, who have traditionally been rationalistic in their approach, are also turning their attention to empirical issues. Thus, we see emerging a new and strong interaction between musical acoustics on the one hand and music theory on the other. It is expected that considerable advances will be made in the understanding of music perception over the next decade.
Voice as a musical instrument
Authors: Titze J. R.
Published: October 2005

A comparison between voice as a periodic sound source in speech and voice as a musical instrument is made on the basis of physiological and acoustic differences. Oral acoustic output power is about 1000 times greater in maximal effort singing than in conversational speech, and vocal efficiency can be 100 times greater. This makes optimization of laryngeal and pharyngeal configurations an important performance task. Recent research demonstrates that a somewhat lowered larynx, stable respiratory and phonatory configurations based on nearly isometric contractions of opposing muscles, and formation of an upper laryngeal resonator for high-frequency emphasis (the singing formant) are key factors. Fundamental frequency control over a range of several octaves is accomplished by intrinsic laryngeal muscular contraction, but nonlinear tissue characteristics of the vocal folds can account for an amplitude tuning by pulmonary effort. The quality of the tone is dominated by two major register adjustments in the larynx, but a larger number of minor register effects are perceived on the basis of vocal tract loading. This source-system interaction, which depends on vocal tract dimensions, in conjunction with the size of the vocal folds, establishes a scaling principle for voice classification on both physiological and acoustic levels. Training of the instrument and training of the artist is an inseparable process. Evidence is yet scarce that a good singing voice, like a good violin, is structurally determined. If so, what are the key morphological elements? If not, is the quality improved by overall muscular strengthening, by differential adjustment and accurate coordination of specific muscles, or by biological adaptation of mechanical tissue properties?
A brief history of violin research
Authors: Hutchins Carleen M.
Published: October 2005

Underpinnings making possible present day violin research have been provided by such well known figures as Gallileo, Mersenne, Hooke, Saveur, Fourier, Chladni, Poisson, Helmholtz, Rayleigh, Dayton Miller, Erwin Meyer, and manufacturers of modern electronic and optical equipment. First known extensive investigations in violin acoustics were done in early 19th century France by Felix Savart. Not until early 20th century did a continuous research flow emerge. Today there is fairly good knowledge of what goes into the violin and what comes out based on extensive studies of: vibrational characteristics of bowed strings; overall spectral content of violin sounds with variations from one instrument to another; vibrations of the violin bridge; Eigenmodes of free plates; geometries of air resonances of the violin cavity; acoustical properties of suitable wood and other materials. We are beginning to understand how free-plate Eigenmodes affect tone quality, but we don't know how they relate to the coupled modes of both wood and air in the bowed instrument. We don't know exactly how the nonlinear bow-string mechanism activates the instrument, nor how vibrations of the bridge relate to those of each violin for desired tone quality; and we don't know how Chladni patterns of the vibrating box affect radiated sounds, nor how they are altered by changes in position and other soundpost variations. Also we have relatively little psychoacoustical information for correlation of subjective musician judgements with physical effects amenable to measurement and analysis. Since the early 1900s research has been done in laboratories around the world and considerable goes forward today on highly technical level which should provide new insights into old problems. Highlights of this will be discussed. An excellent survey of currrent developments is: “The Acoustics of Stringed Musical Instruments,” M. E. McIntyre and J. Woodhouse, Interdiscip. Science Rev. 3, No. 2 (1978).
Suppression of saturation effects in finite amplitude waves
Authors: Woodsum Harvey C.
Published: October 2005

The energy conservation equations due to Westervelt [Proc. 3rd. Int. Congr. Acoustics, edited by L. Cremer (Elsevier, Amsterdam, 1960), p. 316] are used to show that saturation effects in a finite amplitude wave can in principle be suppressed, if the attenuation coefficient at the second harmonic frequency of the primary wave can be selectively increased. Introduction of bubbles which are resonant at the second harmonic frequency is proposed as a scheme for practically implementing this idea. In the case of a parametric array, the parameter of nonlinearity also increases when the bubbles are introduced, thus, parametric efficiency can be enhanced while saturation is simultaneously suppressed.
Experimental research of interaction between sound with sound in a tube
Authors: Xiu-fen Gong , Gong-huan Du , Zhe-min Zhu
Published: October 2005

When a finite amplitude wave of frequency f1 and a weak signal wave of frequency f2 propagate collinearly, an amplitude suppression of the weak waves occurs thru the nonlinear interaction, the energy of suppression is transferred to the production of the sideband components with frequency f2 as a center. The above mentioned theoretical prediction has been experimentally proved in our laboratory. In order to study the interaction for plane progressive wave we used a 9-m long iron tube with square section 4 × 4 cm2 and an absorbing termination. The conditions used in our experiment were:f1 = 980 c/s, SPL1 = 130–150 dB;f2 = 4000 c/s. SPL2 < 100 dB, where SPL, is sound pressure of finite amplitude wave f1, and SPL2 that of weak signal f2. The experiment was performed in the preshock region. In the experiment, it was found that maximum suppression of weak signal was 43 dB as SPL1 = 147 dB, and the sideband components with frequency f2 as center occurred simultaneously, but with nonsymmetrical amplitude distribution. Experimental details will be described and discussed.
The use of SEA in shipbuilding
Authors: Lyon Richard H.
Published: October 2005

The prediction of vibration and sound transmission in ship structures is a recent and potentially important area of SEA applications. The developments of these applications in the U.S., Europe, and the Far East is reviewed. These developments include both experimental studies and analytical analyses (including computer studies). There are several issues to be resolved in this work which include the role of in-plane vibration of the hull and the degree to which reverberation in the structure does or does not dominate traveling wave effects.
Statistical energy analysis prediction of the response of offshore structures to random wave excitation
Authors: Vandiver J. Kim
Published: October 2005

The principle of reciprocity is applied to dynamic response prediction of structures excited by ocean waves. It is shown that the modal wave force spectrum may be expressed in terms of the modal radiation damping coefficient. This leads to the familiar SEA result: that the damping controlled response of the resonator (a mode of an offshore structure) has an upper bound, which occurs when the ratio of the radiation to the total damping approaches unity. This result is embodied in a general method for predicting the damping controlled response of a broad variety of ocean structures. The method includes the effects of the highly directional nature of ocean wave spectra. Example calculations are presented for fixed and floating structures, and the results of full scale tests are reported.
Concepts and applications of SEA: Review and extrapolation
Authors: Smith P. W.
Published: October 2005

The history of developments in theory, experiments, and applications of SEA is reviewed and compared with that of similar methods of analysis in other fields of acoustics. A summary discussion of basic concepts distinguishes between fundamental hypotheses and hypotheses of convenience. Conjectural extrapolations into the future are offered.
The perception of Chinese speech sounds in masking noise and frequency distortion
Authors: Zi-wei Bao , Rong-jue Wei , Wei Y. T.
Published: October 2005

The intelligibility tests of Chinese speech sounds were taken under five masking conditions, namely white noise, pink noise, speech noise, meaningful speech interference, and reverberation masking in auditorium, as well as under a quiet studio condition. To simulate the actual communication circumstances, the noise was introduced to input and output ends, respectively. The signal to noise ratios were varied with a fixed speech level about 80 dB at 1 m from the loudspeaker. In addition, the speech and noise were processed with high-pass, low-pass, or band-pass filtering except in reverberation. A set of simplified but rather sensitive word lists which were based on varying the initial consonants because of the higher sensitivity of initials to masking than finals were used. The effects of masking and frequency distortion on the perception of individual Chinese speech sounds will be presented in this report, with the conclusion that monosyllabic Chinese words or “characters” should be considered as an integral part of sound unit. The tones (or inflection of pitch) with patterns preserved are demonstrated by tape recordings.
Hearing loss in relation to physical properties of experimentally induced middie-ear effusions
Authors: Wiederhold M. L. , Zajtchuk J. T. , Vap J. G. , Paggi R. E.
Published: October 2005

It is commonly assumed that effusions present in the middle ear for a short duration are thin and produce a mild hearing loss whereas effusions present for a longer duration become more viscous with time and produce a greater hearing loss. In order to test this hypothesis, we have used cats with the eustachian tube (ET) ligated on one side to produce middle-ear effusions. Auditory nerve responses to broad-band clicks were reported from the ear canal. Plots of N1 response amplitude and latency versus click SPL were constructed. Hearing loss was determined as the average displacement along the SPL axis of the latency plot, relative to a previously recorded control species. Viscosity of effusion was measured with a cone and plate viscometer. Specific gravity was measured using a 1 cc pycnometer. Middle-ear pressure was assessed tympanographically. After ET ligation all cats developed negative middle-ear pressure within 3 days and flat (Type B) tympanograms within 7 weeks. Hearing loss also develops early and becomes maximal at about 3 weeks. The data indicate there is not a significant difference between the amount of hearing loss associated with thin fluids and with glue. Viscosity is not clearly related to the duration of time the fluid was present in the middle ear. There is a significant positive correlation between the amount of hearing loss and the volume of fluid present in the middle ear. Thus, the amount of hearing loss appears to depend only on the volume of effusion and is not significantly dependent on other physical properties of the fluid.
Reliable piezoelectric ballistic impact detector
Authors: Ivey Larry E. , Henriquez Theodore A.
Published: October 2005

A unique piezoelectric device has been developed to meet the Army's need for a more effective and economical sensor for the hit detection system used on rifle and tank firing ranges. The new sensor was designed to replace a relatively expensive unit that works well on a sheet metal target but is difficult to install and is not adaptable to cheaper target materials. Field tests showed that not only is the new impact detector more effective than the original sensor but it also is capable of discriminating against false indications that may be caused by a muzzle blast, debris thrown against the target by near misses or short rounds, or vibrations from other causes such as wind. The new sensor is excited by compressional waves set up inside the target material. The original sensor was excited by transverse (bending) waves and that is the reason why the unwanted signals excited it.
Audiometric and histologic comparison of noise- and drug-induced cochlear pathology in the chinchilla
Authors: Vertes D. , Nábělek I. V.
Published: October 2005

The purpose of this investigation was to compare audiometric and histologic evidence of drug- and noise-induced hair cell pathology present in the chinchilla two and six weeks after the end of treatment. Behavioral audiometry was accomplished using a shock-avoidance conditioning paradigm, cochlear tissues were prepared using a surface preparation technique and cellular damage was estimated by means of interference-contrast microscopy. Results of the study indicate that after drug treatment the location of hair cell damage and the frequencies where hearing loss occurred agreed fairly well but the number of damaged hair cells and the amount of threshold shift did not. Less cellular damage was present six weeks than two weeks after the end of drug or noise treatment. The implications of large individual variations between animals is discussed.
Spectrum Measurements in a Somewhat Reverberant Room
Authors: Benade A. H.
Published: October 2005

The sound energy density maintained in a room at the (nearly) discrete frequency ω produced by a musical instrument is proportional to the quantity A(ω)=D(ω)⋅δω⋅T〈∫ψ̇φdS〉av. Here D(ω) is the frequency density of room modes, the φ's are pressure wavefunctions belonging to the room, T is the mean reverberation time for these modes, and ψ is the surface displacement of the second source. Integration is over the source surface, and the averaging is over room modes within the bandwidth δω. The latter depends on (1/T) via the Schroeder frequency, and on the “natural linewidth” of the source spectrum: A is dependent on the linear size L of the source via some fraction of (ωL/c). Room selection and microphone and player location for meaningful spectrum measurement may be guided by general properties of A, φ, and D. A violin recording and transposition to synthesize the sounds of the Hutchins family of new violins will be demonstrated as an application of these principles. Calibration procedures will also be described.
Intensity, spectrum, and directivity of turbulent boundary layer noise
Authors: Tam Christopher K. W.
Published: October 2005

The problem of noise radiated from a turbulent boundary layer is studied. It is found that the farfield noise power, spectrum, and directivity can be determined completely if the nearfield pressure cross−correlation function is known. The role of supersonic and subsonic pressure components associated with the turbulent boundary layer in relation to noise radiation is examined. By using an empirical model of wall pressure cross−correlation function, it is found that the directivity pattern of turbulent boundary layer noise differs considerably from that of a free dipole. One principal reason for this difference is the fact that the noise sources of a turbulent boundary layer are constantly in motion. The effect of mean flow outside the boundary layer on the radiated noise power and spectrum is also investigated. Numerical results indicate that this effect is very important for low frequency noise components and for a high subsonic flow Mach number.

Subject Classification: 28.65; 50.55.
Determination of sonic velocities from reflectivity losses at sea ice/water boundaries
Authors: Mayer Walter G. , Behravesh Mohamad , Plona Thomas J.
Published: October 2005

Reflectivities are calculated as functions of sonic incidence angle, densities, and sonic velocities. The resulting sets of curves are used to determine under which conditions reflectivity measurements can or cannot yield information about the values of sonic velocities and density of sea ice.

Subject Classification: 30.25, 30.30.
Attenuation of sound by rigid spheres: measurement of the viscous and thermal components of attenuation and comparison with theory
Authors: Foner S. N. , Nall B. H.
Published: October 2005

An acoustic cavity technique has been developed to separately measure the viscous and thermal components of the attenuation of sound by rigid spheres in various gases. A rigorous quantitative test of theoretical predictions for the individual components of attenuation has been carried out for spheres of known size in argon, nitrogen, and dichlorodifluoromethane (Freon−12), gases selected to cover a wide range in the relative influence of thermal damping to viscous damping. Theory and experiment are in good agreement in regard to both qualitative and quantitative features. Qualitatively, the most striking feature observed is the sinusoidal variation of attenuation with displacement of the spheres along the cavity axis, as predicted by theory. The absolute values of the viscous and thermal damping constants agree quite well with theory. Even better agreement with theory is obtained for the difference between viscous and thermal attenuation, a measurement that does not require opening the cavity to insert or remove the spheres. In addition, the damping produced by the slender cylindrical translating rod exhibits some interesting structure which can be quantitatively explained by theory.

Subject Classification: 35.20; 20.35.
Small−amplitude sinusoidal waves in an elastic mixture with binary chemical reactions
Authors: Nunziato Jace W. , Walsh Edward K.
Published: October 2005

The propagation of small−amplitude sinusoidal waves in a chemically reacting mixture of nonconducting elastic materials is considered. Limiting attention to mixtures with binary reactions, we derive expressions for the phase velocity and attenuation of infinitesimal sinusoidal waves and examine the influence of the thermochemical properties of the mixture on the wave behavior. The general relation between small−amplitude sinusoidal waves and acceleration waves is also established.

Subject Classification: 35.26.
High−frequency vibrations of crystal plates under initial stresses
Authors: Lee P. C. Y. , Wang Y. S. , Markenscoff X.
Published: October 2005

A system of six two−dimensional plate equations is derived for motions of small−amplitude waves or vibrations superimposed on finite, elastic deformations due to static, initial stresses. In the stress−strain relations, the nonliner terms associated to the third−order elastic stiffness coefficients are included. These equations accomodate the coupling of the six lowest modes of vibration, i.e., the flexure, extension, face−shear, thickness−shear, thickness−twist, and thickness−stretch modes, and all their anharmonic overtones. The new equations are applied to the rotated Y cuts of quartz in studying the thickness−shear and flexural vibrations. The changes in the resonance frequencies of the fundamental thickness−shear vibrations are computed as functions of the direction of initially applied force and of the angle of rotated Y cuts. The predicted results are compared with experimental data and with existing computed results. An explicit formula is obtained for the change of fundamental thickness−shear frequencies in terms of initial deformations and the second− and third−order elastic stiffness coefficients.

Subject Classification: 40.24.
Loudness enhancement in man. I. Brainstem−evoked response correlates
Authors: Bauer J. W. , Elmasian R. O. , Galambos R.
Published: October 2005

This paper correlates electrophysiological responses and psychophysical judgments in subjects performing in a loudness enhancement task. Subjects received a tone burst Tc followed after an interval (ΔT) by a signal S1 whose loudness they were required to match by adjusting the intensity of another signal S2 presented 1.5 sec later. They judged the loudness of S1 to be enhanced by 15 dB or more when ΔT was small. Analysis of the electrophysiological brainstem responses evoked by S1 and S2 (as recorded via scalp electrodes) revealed no changes in the electrophysiological response to S1 that could explain its loudness enhancement. A latency measure decreased and a power spectrum measurement increased for both S1 and S2 as their physical intensity was raised, but presenting Tc prior to S1 had either no effect or the opposite effect by either measure despite the large perceived enhancement of S1 loudness. These results show the brainstem response to reflect stimulus intensity changes accurately, and perceived (enhanced) loudness change poorly or not at all. The mechanisms mediating loudness enhancement probably operate, therefore, at levels central to the brainstem.

Subject Classification: 65.44, 65.50.
Interaural phase and amplitude relationships of bone−conduction signals
Authors: Tyszka Frederic A. , Goldstein David P.
Published: October 2005

Masking level differences (MLDs) were used as a means of studying the interaural phase and amplitude relationships for a 500−Hz bone−conduction signal from both the mastoid and the forehead vibrator positions. The results of the investigation indicated that with the vibrator on the forehead there is a trend for a 500−Hz bone−conduction signal to be interaurally in phase and interaurally equal in amplitude. With the vibrator on the mastoid there is a trend for the bone−conduction signal to be 180° interaurally out of phase and interaurally equal in amplitude.

Subject Classification: 65.62, 65.60, 65.58.
Stimulus familiarity and ear superiority in dichotic listening
Authors: Nachshon Israel , Carmon Amiram
Published: October 2005

The effects of speech lateralization, stimulus familiarity, and their interaction on ear superiority in dichotic listening were investigated. In two tests, dichotic pairs of consonant−vowel monosyllables were presented. In the first test, the consonants, and in the second, the vowels, varied, while the other member of each monosyllable was kept constant. In each test, the varying stimuli had to be identified. Four conditions were created in each test by pairing either two familiar or two nonfamiliar monosyllables, or familiar with nonfamiliar monosyllables. Consonants were better identified from the right ear, except when familiar consonants in the left ear were paired with nonfamiliar consonants in the right ear. Vowels were identified equally well from the two ears when both vowels in the dichotic pairs were equally familiar or nonfamiliar. When familiar vowels were paired with nonfamiliar vowels, the familiar vowels were always better identified. The results thus show that the differential report from the two ears is affected by both stimulus familiarity and language lateralization.

Subject Classification: 70.30.
Laminated composite shells under time−dependent internal pressure
Authors: Sun C. T. , Sun Patrick W.
Published: October 2005

In this note the dynamic response of simply supported cylindrical composite shells is investigated by using the classical method of separation of variables. Subject Classification: 40.26
Two 50% probabilities
Authors: Andrews Frank A.
Published: October 2005

The concept, detection probability, is used in two different ways in assessing sonar performance. In both cases, the value 50% appears frequently. The first use occurs in the detection process itself, where the signal−to−noise power required for a detection probability of 50% is usually called ’’recognition differential’’ and sometimes ’’detection threshold.’’ The second use occurs in the prediction of the sonar range under conditions of uncertainty. In this latter case, the range at which one−half the members of an ensemble of targets and environmental conditions will be detected is often called ’’50% probability detection range.’’ The relation between the two probabilities will not be found in standard text books on sonar systems, and is therefore submitted here.

Subject Classification: 60.10.
Fundamental frequency rules for the synthesis of simple declarative English sentences
Authors: Olive Joseph P.
Published: October 2005

A recent experiment by Olive and Nakatani [J. P. Olive and L. H. Nakatani, ’’Rule−synthesis of speech by word concatenation: a first step,’’ J. Acoust. Soc. Am. 55, 660−666 (1974)] has shown that when telephone numbers were rule−synthesized by splicing together numbers which were spoken in isolation, the proper adjustment of fundamental frequency was more important than adjustments of amplitude, duration, and between word coarticulation, for making these spliced numbers sound as if they were spoken naturally. This experiment also showed that in the case of telephone numbers, fundamental frequency adjustments were sufficient for providing synthesis by rule of quality comparable to the quality of natural speech which was processed by an analysis−synthesis procedure. This paper describes the next step in our research of rule synthesis: the study of a restricted set of sentences of simple syntactic structure, instead of telephone numbers. Methods for studying fundamental frequency contours of naturally spoken sentences are discussed; some fundamental frequency rules for synthesizing short English sentences are derived from these natural utterances. More specifically, only rules which are dictated by the syntax were investigated; the appropriateness of these rules was determined by incorporating them into a computerized rule−synthesis scheme.

Subject Classification: 70.50.
Scattering−matrix description and nearfield measurements of electroacoustic transducers
Authors: Kerns D. M.
Published: October 2005

Recently developed and successfully applied analytical techniques for the measurement of microwave antennas at reduced distances are ’’translated’’ into corresponding techniques for the measurement of electroacoustic transducers in fluids. The basic theory is formulated in scattering−matrix form and emphasizes the use of plane−wave spectra for the representation of sound fields. This theory, in contrast to those based on asymptotic description of transducer characteristics, is suitable for the formulation and solution of problems involving interactions at arbitrary distances. Two new techniques (in particular) are described. One, utilizing deconvolution of transverse scanning data, taken with a known tranducer at distances d which may be much less than the Rayleigh distance dR(≡ D2/2), provides a means of obtaining complete near− and farfield characteristics, corrected for the effects of the measuring transducer. Applicability of a (two−dimensional, spatial) sampling theorem and the ’’fast Fourier transform’’ algorithm, which greatly facilitate the necessary computations, is shown. The second technique provides a means of extrapolating received signal as a function of distance (observed with d ∠ dR) to obtain on−axis values of effective directivity. Other possible applications are indicated. These techniques rigorously utilize observed transducer output, which need not be simply related to pressure or normal velocity at a point.

Subject Classification: 85.40, 85.62; 30.85.
New acoustic resonator for liquids in the 0.2− to 2−MHz range
Authors: Eggers F. , Funck Th.
Published: October 2005

A new acoustic resonator with nonplanar quartz transducers for liquids (sample volume about 20 ml) in the 0.2− to 2−MHz range is described. The application of static overpressure onto the liquid cavity causes concave bending of both quartz transducers. This reduces loss contributions from diffraction and ’’side−wall effects’’ considerably, resulting in higher Q values for this resonator; moreover, air inclusions in the cavity are suppressed.

Subject Classification: 35.24, 35.80.
Investigation of critical−angle ultrasonic phenomena by Bragg diffraction of laser light
Authors: Powers John P. , Brown Robert D.
Published: October 2005

A laser beam probe is used to study ultrasonic phenomena at a liquid−liquid interface. In particular, the technique has been used to detect and quantify evanescent waves generated at such an interface when the critical angle of incidence is exceeded. A mathematical description of the properties of evanescent waves is also given.
Distribution of natural frequencies in certain structural elements
Authors: Elishakoff I.
Published: October 2005

The paper deals with the natural frequency distribution in beams, plates, and shallow spherical shells. Expressions are found for the distribution functions (number of modes not exceeding a given cutoff level), for these integral approximations, and for the frequency derivatives of the latter—the so−called smeared modal densities. Special attention is paid to the singularities in these densities (present in certain elements), which were noted by Bolotin and are referred to in literature as ’’condensation points.’’ It is shown that omission of the concept of lowest natural frequency leads to a physical paradox, and that the findings of most studies of modal densities should be revised. The method of integral approximations is applied to the problem of random vibrations of a shallow spherical viscoelastic panel. It is shown that the integral approximation of the averaged spectral density in the high−frequency range is equivalent to an infinite−system model, and, moreover that the physically inconsistent results reported in literature regarding infinite discontinuities in the spectral densities of damped shells are erroneous and due to application of asymptotic expressions, valid only at high frequencies, to the low−frequency range.

Subject Classification: 40.22, 40.24, 40.26, 40.35.
Comparison of Statistical Energy Analysis power flow predictions with an ’’exact’’ calculation
Authors: Remington Paul J. , Manning Jerome E.
Published: October 2005

Statistical Energy Analysis (SEA) predictions of the power flow between two multimodal dynamic systems, i.e., two rods vibrating in compression, are compared with an exact calculation. The exact calculation when averaged in sufficiently broad frequency bands is found to agree closely with the SEA predictions for both strong and weak coupling.

Subject Classification: 45.40.
Chamber for reverberant acoustic power measurements in air and in water
Authors: Blake William K. , Maga Lawrence J.
Published: October 2005

A reverberant chamber for use with both air and water media is described. The chamber is used to investigate the acoustic coupling of simple vibrating structures under conditions of light or of heavy fluid loading. Calibration was effected by measuring 60−dB reverberation times in 1/3−octave bands; decay times on the order of 2 sec in air and the order of 0.2 sec in water were observed. These results were cross checked in water by measuring the spectrum of acoustic pressure in the chamber generated by a calibrated hydrophone source. Sound−pressure levels measured in narrow (50−Hz) bands varied ±3 dB spatially in the air−filled chamber and ±5 dB spatially in the water−filled chamber.

Subject Classification: 55.65; 50.25; 45.10.
Mechanisms of masking
Authors: Moore B. C. J.
Published: October 2005

Some of the strategies which an observer might use in detecting a tone presented against a background of noise are discussed. In Experiment I thresholds for tones in noise were measured under a number of different conditions, using flat−spectrum and notch−filtered noises, in a two−interval forced−choice task. Threshold did not correspond to a constant difference in critical−band levels on the two halves of the trial. Performance at the highest frequency used (6.1 kHz) was worse than at lower frequencies (1055 and 4080 Hz), and, in contrast to them, was not independent of overall level. This is contrary to the classical data, and indicates that the critical ratio is not a constant fraction of the critical band. In Experiment II the intensity discrimination of 1/3−octave bands of noise was studied. The noises were presented alone or in a wide−band noise background. For noise bands presented alone, performance is roughly independent of overall level, and improves slightly with increasing center frequency. For noise bands presented against a wide−band noise background, performance is independent of overall level for frequencies up to 4 kHz. A change in level of about 2−3 dB is necessary for 75% correct detection. For frequencies above this, performance worsens with increasing overall level. These results may be explicable in terms of a saturation of neurons at high intensities. The saturation effects are not observed at low frequencies, possibly because the primary cue for detection is a change in the temporal pattern of neural firing, rather than a change in amount of neural firing.

Subject Classification: 65.58, 65,35.
Finite−element approach to acoustic scattering from elastic structures
Authors: Hunt John T. , Knittel Max R. , Nichols Charles S. , Barach Don
Published: October 2005

An approximate method is presented for solving the equations of motion that describe the scattering of an acoustic wave by an elastic structure immersed in an infinite fluid medium. The mathematical model that is developed uses the finite−element method to calculate the vibrational response of the elastic body and to calculate the acoustic pressure field of a finite volume of the fluid medium which closely surrounds the elastic body. Analytical methods are used to obtain the boundary conditions for this mathematical model. Results are presented for the total scattering cross section, axial pressure, and scattering patterns for an acoustic plane wave at normal incidence on an aluminum disk.

Subject Classification: 30.30, 30.40.
Predictions of volume scattering strengths from biological trawl data
Authors: Love Richard H.
Published: October 2005

A volume reverberation model which utilizes fish distribution data has been developed to permit quantitative predictions of depth−dependent scattering strengths. The model was evaluated by using coincident acoustic volume scattering measurements and biological trawl data collected in the Mediterranean Sea. Biological specimens were collected at discrete depths with an Isaacs−Kidd midwater trawl. Each fish collected was identified and sized, and its acoustic cross section calculated by utilizing regression equations relating fish species, length, and swimbladder volume at frequencies near swimbladder resonance, or equations relating fish length to acoustic cross section at frequencies far above resonance. Scattering strengths for each species were then determined, indicating dominant species at each trawl depth for 1/3−octave frequency bands between 2.5 and 20 kHz. The acoustic data were obtained with surface−vented explosive sources and a shallow onmidirectional hydrophone. These data were processed to yield integrated column strength versus depth profiles, which were then numerically differentiated to produce scattering strength versus depth profiles for each frequency band. Comparison of the model predictions to the scattering strength profiles showed good agreement at the higher frequencies, with the agreement decreasing with frequency below 6.3 kHz.

Subject Classification: 30.30, 30.40.
Sound propagation and attenuation in the deep ocean at very long ranges
Authors: Nomady V. G. , Überall H.
Published: October 2005

Sound propagation in a deep−ocean sound channel is investigated theoretically. A normal−mode series solution which includes effects due to curvature of the earth is obtained as the residues in a pole series arising from the Watson transformation. Analytic expressions are found for the pressure amplitudes due to a continuous wave source using an Epstein sound velocity profile. Attenuation−versus−range curves are given for both phased and random modal sums. The continuous wave solutions are then used for the pulsed source problem. Dispersion curves are obtained. The higher−order modes are shown to arrive earlier, in agreement with experiment. An analytic expression for the pressure of a pulse as a function of time is obtained. The shape of the pulse at a range of several hundred miles is shown and agrees qualitatively with experimentally obtained pulse shapes. Such pulses begin at a low amplitude, increase to a relatively large amplitude peak, then cut off abruptly.

Subject Classification: 30.20.
Reaction−time procedure for measurement of hearing. I. Suprathreshold functions
Authors: Pfingst Bryan E. , Hienz Robert , Kimm Joseph , Miller Josef
Published: October 2005

Reaction time (RT), or response latency, to auditory stimuli has been suggested as a measure of loudness in nonverbal animals as well as in man. In this study RT functions were obtained for human and rhesus monkey subjects under normal conditions and under conditions of hearing impairment. In both humans and monkeys RT varied in a similar manner with changes in intensity and frequency of the stimulus, and in response to experimental manipulation of the receptor organ. The study demonstrated that latency functions are similar to functions derived by loudness−matching procedures in humans: in subjects with normal hearing, equal−latency contours corresponded closely with equal−loudness contours. In subjects with impaired hearing, matched−latency and matched−loudness contours also corresponded closely. Rate of decrease in RT with increasing intensity is discussed and related to rate of growth in loudness. The results suggest that RT is a valuable measure of suprathreshold hearing in human and nonhuman primates.

Subject Classification: 65.50, 65.64, 65.66, 65.75; 85.24.
Acoustic characteristics of English /w,r,l/ spoken correctly by young children and adults
Authors: Dalston Rodger M.
Published: October 2005

This report presents the results of a spectrographic analysis of word−initial allophones of /w/, /r/, and /l/ produced by three− to four−year−old children and adults. Information was obtained concerning formant frequencies, steady−state durations, transition durations, and transition rates of each of the first three formants of these sonorants. The results demonstrate that the phonemes investigated are distinguishable on the basis of their temporal, as well as their spectral, acoustic characteristics.

Subject Classification: 70.20, 70.40.
Assessment of hearing handicap: comment on the ’’Kryter series’’
Authors: Noble William G.
Published: October 2005

The assessment of hearing handicap resulting from exposure to noise has been extensively discussed by Kryter [J. Acoust. Soc. Am. 53, 1211−1234 (1973)] and by subsequent commentators. It is argued that many problems and relevant findings on this issue have been overlooked in that series. It is further argued that a measure based on self−report holds more promise for the valid assessment of hearing handicap resulting from noise−induced hearing loss than performance tests of auditory pure−tone sensitivity or speech reception.

Subject Classification: 65.64.
Quantitative measurements of acoustic emission related to its microscopic mechanisms
Authors: Hatano Hajime
Published: October 2005

A method for the quantitative measurements of the acoustic emission is worked out. Its performance is analyzed with regard to the transducer loss and the ultrasonic attenuation in the specimen. This method is actually applied to the tension tests of pure aluminium specimens. The power spectrum of the acoustic emission is obtained over a wide range of 100 kHz to 4 MHz. The total power attains a peak of 5 pW at the beginning of the plastic deformation and decreases to 0.3 pW with the increase of the deformation. The autocorrelation function for the acoustic emission is given as a monotonically decreasing function. This result reveals that the elastic energy of the acoustic emission is radiated not oscillatorily but in the form of random pulses. Mean value of the pulse widths is estimated to change from 0.6 to 0.2 μsec in the early stages of the deformation. This change is shown to be attributable to the increase of the density of dislocations in the material.

Subject Classification: 35.10.