bluuebunny/crossref_metadata_2025 huggingface dataset:
Finite-Amplitude Sound-Wave Propagation in a Waveguide
Authors: Keller Joseph B. , Millman Martin H.
Published: October 2005

A sound wave with angular frequency ω and finite amplitude ε, propagating in a rigid waveguide of any non-rectangular cross section, is considered. The pressure and velocity potential of the wave, corresponding to each mode of the linear theory, are determined as power series in ε. The leading term is just the mode given by the linear theory and further terms are finite-amplitude corrections to it. The wavenumber or propagation constant kn of the nth mode is found to depend upon ε and is also determined as a power series. The fact that kn depends upon ε, and the expression for kn(ε), is the most interesting consequence of the analysis. This shows that the propagation velocity ω/kn depends upon ε. The results are specialized to a waveguide of circular cross section. Then numerical values of kn(ε) are given for a circular guide filled with air for n = 1, 2, 3, 4, and 5. The lowest mode (n = 0) is not considered because shocks occur in it. The method of analysis is a perturbation expansion adapted to eliminate secular terms. It has been used before to treat periodic finite-amplitude sound waves in a closed container and periodic finite-amplitude vibrations of strings and beams by J. B. Keller and L. Ting [Comm. Pure Appl. Math. 19, 371 (1966)], and to treat nonlinear electromagnetic wave propagation [Phys. Rev. 181, 1730 (1969)] and other nonlinear boundary-value problems by the authors [J. Math. Phys. 10, 342 (1969)].
Propagation, Distortion, and Shock Formation of Pressure Pulses in a Nonviscous Fluid of Constant State
Authors: Schindler G. M.
Published: October 2005

Plane simple compression waves of finite amplitude are studied as they propagate into a fluid medium of constant state. Shock formation and subsequent expansion, as well as rise and decay of shock strength, are determined from a boundary-value problem of mixed type involving a fixed boundary (source) and a moving boundary (shock surface). At the source, an overpressure is arbitrarily prescribed as a function of time; at the shock surface, the simple wave solutions are shown to satisfy the exact shock-transition conditions within an accuracy including second powers of shock strength, while the shock speed is determined precisely. Shock speed and rise and decay of shock strength are shown to be strongly dependent on the particular form of the overpressure generated at the source in the course of time. Approximation formulas are derived for weak shocks and are used in a detailed discussion of two examples.
A Canonical Form of the Likelihood Detector for Gaussian Random Vectors
Authors: McDonough R. N.
Published: October 2005

In this paper, the likelihood ratio detector for zero-mean complex Gaussian vector signals in zero-mean complex Gaussian vector noise is considered. The receiving apparatus is assumed to be spatially distributed, and only a single frequency of interest is treated. By simultaneous diagonalization of the signal and noise spatial covariance matrices, say S and N, a canonical form is found for the familiar detector appropriate to this problem. Using this canonical form, a number of special cases follow easily. First, for small signals such that all eigenvalues of SN−1 are less than 1, we obtain the approximate detector. We then obtain the usual matched filter and threshold for the plane-wave signal case, and a generalization to the case of a signal which is a superposition of plane waves. Finally, for signals such that the smallest nonzero eigenvalue of SN−1 is greater than 1, we obtain the asymptotic detector. Few of the results presented are new, but it is hoped that their derivation in a unified way from the canonical detector will be illuminating. Our aim is to combine some standard communication-theory techniques with some standard matrix-theory results, in the setting of the acoustic array data-processing problem.
Contour, Interval, and Pitch Recognition in Memory for Melodies
Authors: Dowling W. J. , Fujitani Diane S.
Published: October 2005

Melodic contour (the sequence of ups and downs in a melody, regardless of interval size) expresses those aspects of a melody that are most essential to manipulation of that melody in various musical structures, e.g., folktunes and fugues. This is demonstrated by brief analyses of actual music. Two experiments demonstrate the role of melodic contour recognition in memory for melodies. Experiment 1 (2×3 factorial design) involved short-term memory with comparison melodies either transposed or not transposed from the key of the standard. Separate groups had the tasks of distinguishing (a) between same and different melodies; (b) between same melodies and ones with only the same contour; and (c) between melodies with the same contour and different ones. The effects of transposition and task and their interaction were significant (p<0.001). Untransposed melodies were recognized by their exact pitches, so that tasks (a) and (b) were equally easy. Contour recognition was more important with transposed melodies, so that task (b) was very difficult, and tasks (a) and (c) were easier. Task (c) was about equally difficult under both conditions. Experiment 2 involved recognition of distorted versions of familiar folktunes having the same length and rhythmic structure. In ascending order of recognizability, these distortions preserved merely the harmonic basis of the melody, the melodic contour, and the contour plus the relative sizes of successive intervals between notes (chi-square = 50.4, p<0.001).
Sweep-Tone Measurements of Vocal-Tract Characteristics
Authors: Fujimura Osamu , Lindqvist Jan
Published: October 2005

The vocal tract was excited transcutaneously at a point just above the glottis by an external sweep-tone signal, in order to measure its transfer characteristics acoustically as continuous frequency functions. An analysis-by-synthesis procedure derived reliable data of vowels, in particular of the formant bandwidths, for three male and three female normal subjects. It has been shown for the closed glottis condition that the first formant bandwidths are higher for close vowels (typically 70 Hz for male subjects) than for semi-open vowels (typically 35 Hz for male subjects). Stationary consonantal articulations including stops, nasals, and nasalized vowels also have been studied, as well as the effect of opening the glottis on the vocal-tract transfer characteristics. The stop articulations give rise to a first-formant frequency slightly below 200 Hz. This fact and the high dissipation of the first formant is explained by assuming nonrigidness of the surrounding wall. Characteristics of nasalized vowels and nasal murmurs are also discussed based on the data obtained in this experiment.
Analysis of Fundamental Frequency Contours in Speech
Authors: Levitt H. , Rabiner L. R.
Published: October 2005

Many factors contribute to the variability of an ensemble of measured fundamental frequency (Fo) contours. These include, among others, differences between speakers, differences between replications of the utterance by the same speaker, and errors of estimation. Unfortunately, the relative contribution of the different sources of variability vary during the course of an utterance. We discuss in detail a method for analyzing such data by subdividing the time axis into a series of time windows and approximating the Fo contour within each window by a set of orthogonal polynomials. An analysis of variance is then carried out on the coefficients of each polynomial expression. Consistent trends in coefficient values between contiguous time windows are then approximated by sets of orthogonal polynomials. The technique is not only a powerful method for evaluating quantitatively the effects of different sources of variability, including changes in the degree of variability during an utterance, but also provides a basis for comparing directly the effect of short-term smoothing of contours with that of approximating long-term trends. Both these effects may also be compared directly with those of averaging over replications or averaging over both subjects and replications. These effects can be rank ordered in terms of a least-squares criterion, thereby isolating those factors which have the greatest influence on contour shape. The technique can also be used to separate out within-subject and between-subject differences in contour shape. An analysis of two utterances repeated three times by each of three subjects showed that inter-replication differences were relatively small and that a good fit to the measured fundamental frequency contours (rms deviation ≈2 Hz) could be obtained by using an average contour for each subject. A single mean contour could be fitted to the entire utterance, but in this case the rms deviation was close to 4 Hz. There were also substantial differences in variability during the course of the utterance, the stressed portions being less variable than the nonstressed portions.
Tentative Audiometric Threshold-Level Standards from 8 through 18 kHz
Authors: Harris J. Donald , Myers Cecil K.
Published: October 2005

Both ears of 100 young healthy men with no previous military noise exposure, aged 17–23 yr and normal by otoscopy but otherwise unselected, were given Békésy-type audiometry through 18 kHz with the Rudmose high-frequency ear-canal insertion transducer. Minimum audible pressures (MAP) were obtained in approximate agreement with published studies on children and on adolescent males. There is also correspondence with the British 1954 Standard MAP up to 15 kHz. It is suggested that the time is approaching for standardizing audiometry in the octave 10–20 kHz by using all available data.
Olivary Responses to Dichotic Stimuli
Authors: Langford Ted L.
Published: October 2005

Previously reported neuronal responses to binaural stimuli are reexamined and compared with data from other laboratories.
Measurements of the Refraction and Diffraction of a Short N Wave by a Gas-Filled Soap Bubble
Authors: Davy Bruce A. , Blackstock David T.
Published: October 2005

The pressure signatures of sonic booms measured in the field often show considerable variations from the ideal N waveshape. Peaked and rounded versions of the N are commonly observed. Pierce [J. Acoust. Soc. Amer. 44, 1052–1061 (1968)] has proposed that peaking and rounding are the result of refraction and diffraction caused by atmospheric inhomogeneities. To test this explanation, we have carried out a model experiment in the laboratory. N waves about 1 cm long were produced by an electric spark, refracted and diffracted by a gas-filled soap bubble, and received by a very wide-range condenser microphone. The microphone output was displayed on an oscilloscope. The spark-microphone distance was held fixed, and measurements were taken with the bubble at various points in between. The bubble acted as a converging acoustic lens when it was filled with argon and as a diverging lens when filled with helium. It was found that the converging lens caused peaking of the N wave, while the diverging lens caused rounding. These results qualitatively support Pierre's theoretical model. The data do not serve as a quantitative test of Pierre's specific numerical examples, however, because the particular conditions he assumed were not reproduced in our experiment. A discussion given of the effect of some of these conditions, such as the order and relative time of arrival of the refracted and diffracted waves, on the waveform. Another factor that had a rather strong influence on the waveform, particularly when a helium-filled bubble was used, was the finite size of the microphone. The waveforms that would have been observed with a true point probe are deduced.
Acoustical Detection of Single Cavitation Events in a Focused Field in Water at 1 MHz
Authors: Coakley W. T.
Published: October 2005

Acoustic intensities up to 1400 W/cm2 have been generated at the focus of a ceramic bowl. The rf voltage applied to the transducer has been rectified and filtered and the signals produced from cavitation events have been examined. A directional hydrophone simultaneously monitoring the focal point aided interpretation of the signals detected by the driven bowl. Low-amplitude low-frequency signals appeared on the driven bowl synchronously with the onset of first subharmonic emission in the water at an intensity of 13 W/cm2. The subharmonic increased rapidly with increasing sound intensity and then leveled off. Just before this occurred, the scattering properties of the focal region increased markedly and a cyclic signal, interpreted as indicating the production of clouds of microbubbles when surface oscillations set in on the cavitation bubbles, was detected on the filter circuit. Strongly radiating single cavitation events lasting for the order of milliseconds were also detected. The amplitude, duration, and rate of occurrence of these events were all one to two orders of magnitude greater in tap than in degassed water.
Observation of Wind-Wave-Generated Doppler Shifts in Surface Reverberation
Authors: Igarashi Yoshiya , Stern Richard
Published: October 2005

Frequency shifts in surface reverberation were consistently observed when a directional transducer was pointed in the direction of ocean wave propagation. The magnitude of the Doppler shift systematically decreased to zero as the transducer was rotated 90° to point toward the cross-wave direction, and the sign of the shift reversed as the transducer was horizontally rotated from the up-wave to down-wave direction. Doppler-shift data were obtained mainly for 110-msec tone transmission at 15 and 60 kHz. The measured shifts were generally in accord with first-order resonance theory and may be attributed to ultragravity waves. Higher-order shifts corresponding to large gravity waves were not observed. The spectral width of surface reverberation was essentially independent of wind and wave directions and roughly three times that of the transmitted pulse for the 60-kHz data, and less wide in the case of 15-kHz transmission. It is hypothesized that orbital motions of the water particles forming the larger-scale ocean wave can impart a radial to-and-fro motion of the ultragravity wavetrain riding on it. Rapid up and down Dopplers induced by this motion are believed to contribute to the observed spectral broadening.
Radiation of Sound by Airfoils that Accelerate near the Speed of Sound
Authors: Lyon Richard H.
Published: October 2005

This work shows theoretically that airfoils accelerating at a speed near to, but less than, the speed of sound can be powerful emitters of sound. The sound generation is due to both lift and thickness effects. The airfoil is replaced by volume velocity and body force distributions, and the solutions are obtained by standard methods. A rotating blade is replaced by a lineal progression of accelerating “torpedoes” representing the rotor tips. The sound of lift and thickness effects is radiated strongly forward. Sound power calculations made for thickness radiation alone for a series of airfoil shapes show some reduction of radiated sound with tip shape, and a promising correlation with experimental results.
Ambient-Noise Measurements at 30, 90, and 150 kHz in Five Ports
Authors: Anderson Aubrey L. , Gruber George J.
Published: October 2005

High-frequency ambient-noise measurements were made in five North American ports. At a given frequency, the total span of noise levels for the five harbors was about 25 dB. At 30 kHz, levels 30 dB higher than the extrapolated deep-water Knudsen value for sea state 2 were observed. Comparison is made with some 20- to 50-kHz data for other harbors.
Resonance-Enhanced Brillouin Scattering in Crystals
Authors: Burstein E. , Ito R. , Pinczuk A. , Shand M.
Published: October 2005

The phenomenological theory of light scattering by optical and acoustical phonons is reviewed. The resonance enhancement of Brillouin scattering by acoustical phonons in the vicinity of the intrinsic absorption edge is related to the enhancement of the elasto-optical and electro-optical constants. A macroscopic theory of resonance-enhanced Brillouin scattering by acoustical phonons analogous to that of resonance-enhanced Raman scattering by optical phonons is formulated in terms of the scattering of polaritons by the acoustic phonons via the exciton and continuum electron-hole pair excitation parts of the incident and scattered polaritons.
Sound Attenuation over Simulated Ground Cover
Authors: Pao S. P. , Evans L. B.
Published: October 2005

In dealing with wave propagation over land below 1000 Hz, ground attenuation is an important consideration. Very often, the actual ground surface is covered with a thick layer of vegetation that has a very high over-all void-to-volume ratio. Such a composite boundary should be represented as layered media in order to assess the ground attenuation effect correctly. The wave attenuation characteristics under such conditions are studied in this paper. It is found through theoretical analysis that a layered boundary gives rise to strong selective absorption in certain frequency bands. Experimental data has been taken under laboratory conditions over a wide range of normalized parameters, and the results quantitatively confirm many aspects of the predictions. Both theory and experiment indicate that significant attenuation to very low frequencies can be expected for sound propagation over a deep layer of vegetation. Other results include the confirmation that there is a strong sound-pressure gradient in the vertical direction near the layered boundary, that the excessive attenuation can increase at most 6 dB per doubling distance, and that the effectiveness of ground attenuation depends critically on the elevation angle of the sound source.
Stochastic Filter Modeling for the Sea-Surface Scattering Channel
Authors: Venetsanopoulos Anastasios N. , Tuteur Franz B.
Published: October 2005

In this paper, the time-varying transfer function of the surface scattering channel is computed from first principles, using an extended Eckart model for the scattering mechanism. By assuming that the probability distribution of the surface is Gaussian with a correlation function having Gaussian form, first and second moments of the transfer function are computed. The effect of various surface parameters, particularly the relative surface roughness, on the channel autocorrelation function can then be easily demonstrated.
FEASIBILITY STUDY FOR THE SELF-CALIBRATION OF THE AUDIOMETRIC TDH-39 EARPHONE
Authors: Joscelyn Edwin R.
Published: October 2005

A method of calibrating the audiometric TDH-39 earphone is developed that eliminates the requirement for expensive calibration equipment. This form of reciprocity calibration has been examined and evaluated for 25 pairs of TDH-39 earphones. Two earphones of a headset are alternately used as transmitters and receivers, acoustically coupled in a small cavity. The electrical, acoustical, and mechanical constants of the transducers are then combined using the absolute averages of the sensitivities of the earphones, where the absolute sensitivity is traceable to the National Bureau of Standards. These sensitivity averages are then integrated with the transmitter-receiver voltage transfer characteristic to obtain a calibrating K factor. The calibrating K factor enables field determination of average sensitivity. By use of a third earphone it is possible to extend the analysis to determine the absolute sensitivity of any one of the three earphones.
Monaural Detection with Contralateral Cue (MDCC). II. Interaural Delay of Cue and Signal
Authors: Taylor M. M. , Clarke D. P. J.
Published: October 2005

In a monaural detection with contralateral cue (MDCC) task, subjects detect a masked signal presented monaurally. A cue containing information relevant to the signal is presented to the other ear. We used a burst of noise as the signal and the same noise burst delayed or advanced by up to 2400 μsec as the cue. For most subjects, performance was best when the cue and signal were approximately simultaneous. When the cue led by about 800 μsec, performance dropped sharply to levels below those obtained without the cue, recovering to the uncued level for yet longer disparities. When the signal led the cue, performance dropped smoothly as a function of timing disparity, and for signal lead greater than about 1000 μsec, the cue had little effect on performance. Although the task subjectively is one of judging the apparent lateralization of the cue, we argue that the lateralization mechanism is not by itself the detecting mechanism.
Descriptions of the Speech of Patients with Cancer of the Vocal Folds. Part II: Judgments of Age and Voice Quality
Authors: Kreul E. James , Hecker Michael H. L.
Published: October 2005

Speech samples of 50 adult male speakers were presented to 22 listeners, who estimated the age of each speaker and rated the adequacy, hoarseness, harshness, and breathiness of his voice. Five of the speakers were patients with cancer of the vocal folds, and five were individually matched normal speakers. It was found that the judgments of age, adequacy, and voice quality were reliable and that they differentiated the pathological and normal speakers. The relationships among chronological age and the judgments of age, adequacy, and voice quality were examined.
Ultrasonic Examination of Proton-Transfer Reactions in Aqueous Solutions of Glycine
Authors: Hussey Matthew , Edmonds Peter D.
Published: October 2005

This paper reports a comprehensive experimental investigation, utilizing ultrasonic techniques to study the kinetics of proton-transfer reactions in nondilute aqueous solutions of amino acids. Ultrasonic absorption and velocity measurements in the range of frequencies 10–130 MHz and of pH 0.96–11.6 are analyzed in terms of single relaxation behavior. Activity coefficients are calculated by three methods; the method based upon standard ionic radii and the mean dielectric constant of the solutions is found to yield the most acceptable estimates. The dependencies of rate constants upon initial concentration of solute, ionic strength, and temperature are displayed in the range 0.25M–1.0M, 0.25M–1.0M, and 22°–37°C, respectively. It is concluded that proton-transfer reactions at amino and carboxyl groups cannot be responsible for significant contributions to the total ultrasonic absorption coefficient of blood in the physiological range of pH.
Acoustic Properties of Cell Nuclei
Authors: Smith A. , Schwan H. P.
Published: October 2005

The acoustic absorption of liver cell nuclei has been determined at frequencies from 1 to 10 MHz. The results, if expressed in terms of sound absorption per weight percentage of protein content, indicate that this specific absorption varies from one type of protein to another.
A New Approach to Analysis and Design of Electromechanical Filters by Finite-Element Technique
Authors: Kagawa Yukio
Published: October 2005

Finite-element method was originally developed for analyzing structures such as beams and shells. A flexure-type composite vibrator has been used as an example to illustrate the application of this method to vibration problems involving coupled mechanical and electrical systems [Y. Kagawa and G. M. L. Gladwell, IEEE Trans. Sonics Ultrasonics SU-17, No. 1, 41–49 (1970); J. Acoust. Soc. Japan 26, No. 3, 117–128 (1970)]. This paper develops and adapts this method for the analysis of electromechanical filters of complex shape and construction. The transmission characteristics of a filter are calculated directly without employing the usual method of an equivalent electrical circuit. Two examples of analysis are introduced for presentation. In the first one, the input and output electrodes are set up on the transducers of a composite vibrator, while in the second, two vibrators are coupled by a pair of bars.
Acoustic Filter Synthesis Using Conjugate Gradient Search Techniques
Authors: Kessler F. M. , Puri N. N.
Published: October 2005

A conjugate gradient optimization technique was successfully applied to the synthesis of reactive mufflers. Those parameters that minimize the differences between a muffler transfer function and a desired transfer function are automatically located, eliminating intuitive parameter selection and analysis. Although a two-parameter search is presented, the procedure can be extended to n-parameter space.
Temperature Dependence of the Piezo-Optic Coefficient of Liquids
Authors: Gottlieb Milton
Published: October 2005

The temperature dependence of the piezo-optic coefficient and the elasto-optic coefficient has been measured for water, ethyl alcohol, methyl alcohol, carbon tetrachloride, benzene, toluene, acetone, hexane, and cyclohexane. Only for the unassociated liquids, benzene and carbon tetrachloride, are the measurements in agreement with simple theory.
Free-Field Correction for Laboratory Standard Microphones Mounted on a Semiinfinite Rod
Authors: Matsui Eiichi
Published: October 2005

A theoretical study has been made on the free-field correction of laboratory standard microphones mounted on a semiinfinite rod. In the analysis, we have discussed the diffraction phenomena of plane sound waves by the actual microphone system, taking into consideration the effect of a recess as well as the interaction between microphone diaphragm and medium. A new method of solving wave equations met with these boundary conditions, called the infinite-matrix method, is presented in this paper. Our whole problem is divided into three parts. The first is concerned with the external free field, which can be solved rigorously by Wiener-Hopf technique; the others refer to the solution of the sound field inside a recess and, finally, to motions of a diaphragm. After putting these solutions into the form of matrix equations with unknown variables, we obtain a system of simultaneous matrix equations by connecting solutions with each other. Numerical results are given for the free-field correction of the Western Electric Company type 640AA microphone. Comparison with the experiment, made at the National Bureau of Standards, indicates that sufficient agreement is obtained.
Antisymmetric Vibrations of a Circular Plate
Authors: Potter D. S. , Leedham C. D.
Published: October 2005

This paper, motivated by the use of “bender” disks with underwater transducers, presents a complete solution of the elastic equations for freely supported thick disks that experience no net radial extension. The solution is complete in that all roots of the frequency equation, both real and complex, are considered when the boundary conditions are satisfied.
Nonlinear Oscillations of Laminated Specially Orthotropic Plates with Clamped and Simply Supported Edges
Authors: Wu Cheng-ih , Vinson Jack R.
Published: October 2005

For large-amplitude oscillations, the work presented previously by the authors for single-layer plates of composite materials, simply supported on all edges, is extended to include laminated plates and six combinations of clamped and simply supported edges. Berger's hypothesis is again used to obtain a set of simplified coupled equations which governs the nonlinear motion of plates. Solutions are obtained using a Ritz-Galerkin method in which the assumed series are products of beam characteristic functions. In addition, small-amplitude vibrations are treated as special cases. Numerical results for fully clamped as well as various combinations of clamped and simply supported boundary conditions are presented.
Covariance Properties of Waves Propagating in a Random Medium
Authors: Chen K. K. , Soong T. T.
Published: October 2005

Extensive studies have been made on the mean or effective properties of waves propagating in a random medium. We present in this paper a set of correlation equations which are useful in the quantitative determination of the covariance properties of the waves. As an example, the problem of a scalar wave propagating in a random medium is considered.
Reviewers' Comments on “A New Approach to the Determination of Acquiring Rays in Singly and Doubly Layered Oceans” [D. T. RAPHAEL, J. Acoust. Soc. Amer. 48, 1249–1256 (1970)]
Authors: Pedersen Melvin A. , White DeWayne
Published: October 2005

The approach presented in the subject paper is new in that it treats cases where the ray parameter is expressed as an explicit function of range and receiver depth. This approach exhibits the mathematical nature of caustic lines in a clear and simple form as contrasted to approaches where the ray parameter is expressed as an implicit function.
Underwater Sound Signals from Some Atmospheric Explosions
Authors: Northrop John , Morrison Michael F.
Published: October 2005

Hydroacoustic signals caused by the summer 1970 French atmospheric explosions are interpreted in terms of propagation between source and receiver through the deed sound channel. The observed signal is similar to the classical slope-generated T phase of shallow-focus ocean margin earthquakes.
PROCESS MEASUREMENTS BY SOUND VELOCIMETRY
Authors: Zacharias Ellis M.
Published: October 2005

Sound velocity is discussed as a parameter for measuring solution concentration, solids content, specific gravity, and bulk modulus. Graphs are given for six products showing the correlation between sound velocity and concentration. Temperature dependency is discussed and an equation is given with supporting examples for determining concentration measurement error.
Recovery from Impulse-Noise Induced TTS in Monkeys and Men: A Descriptive Model
Authors: Luz George A. , Hodge David C.
Published: October 2005

The recovery from impulse-noise induced temporary threshold shift was systematically traced for individual rhesus monkeys and men. In addition to the well-known logarithmic recovery, three other types of recovery were seen (diphasic, plateau, and rebound). A descriptive model is developed for the classification of these recovery functions. The model postulates the existence of two types of temporary threshold shift, process M and process S, both of which may be seen after impulse-noise exposure.
Reversals in the Perception of Noise and Tone Patterns
Authors: Pinheiro Marilyn L. , Ptacek Paul H.
Published: October 2005

Perception of auditory patterns based on an intensity difference was investigated in 20 experienced normal-hearing subjects under binaural and monaural listening conditions. Patterns were made up of either three white-noise bursts or three 1000-Hz tone bursts which were temporally spaced. Bursts within each pattern differed only in intensity and were either loud (L) or soft (S), i.e., each pattern included one of one intensity and two of the other. The six possible patterns were SLS, LSL, LLS, SSL, LSS, and SLL. The loud bursts remained at a constant intensity and the soft bursts were attenuated by either 9, 7, 5, or 3 dB. Patterns were presented at 50 dB sensation level. Tone-burst patterns were easier to perceive and resulted in a larger number of correct responses than noise-burst patterns. However, there was no significant difference between tone-burst patterns and noise-burst patterns in the percentage of errors that were pattern reversals. Symmetrical patterns were reversed more frequently than asymmetrical patterns. Auditory pattern reversals are compared to figure-ground reversal and simultaneous contrast phenomena in vision and are discussed in relation to sensory inhibition.
Detection and Duration Discrimination of Noise Increments
Authors: Rochester Sherry
Published: October 2005

When weak signals are presented in a background of continuous noise, the process of detection and the discrimination of a change in duration appears to be very similar. Two experimental techniques were used to investigate duration discrimination. The procedure in which the difference in duration between signals, ΔT, was varied given a fixed signal-to-noise ratio gave different results than the procedure in which signal amplitude was varied given a fixed ΔT. Although there were marked individual differences, all subjects roughly supported the general conclusion.
Contrast in Detection with Gated Noise
Authors: Sandusky Arthur , Ahumada Al
Published: October 2005

The response bias in YES-NO detection with gated noise and simultaneously gated signal plus noise was found to show both sequential and probability contrast. The sequential dependencies showed that the more recent a signal event, the more the response bias shifts away from YES. Similarly, the more probable the presentation of a signal, the more the response bias shifts away from YES. The response bias in detection with continuous noise usually shows the opposite effect—response assimilation. The probability of a YES response increases with either greater signal probability or with signal recency. It is suggested that the response-bias learning which has been postulated to occur in detection experiments depends on the stability of the judgmental frame of reference provided by the continuous noise. When this basis is removed, as in the present study, the response pattern parallels that usually observed in signal recognition studies for which responses are assumed to depend on the memory of the previous presentations. It is concluded that the response pattern, assimilation or contrast, depends more on the stability of the frame of reference than on the type of psychophysical task.
Monaural Detection with Contralateral Cue (MDCC). III Sinusoidal Signals at a Constant Performance Level
Authors: Taylor M. M. , Clarke D. P. J. , Smith S. M.
Published: October 2005

This paper continues the presentation of data describing detection performance in the monaural detection with contralateral cue (MDCC) situation. Subjects detected a monaural sinusoid burst masked by continuous white noise, either with or without an unmasked contralateral cue. The cue, presented in both intervals of each two-interval forced-choice trial, was a sinusoid of the same frequency and duration as the signal, but its phase and intensity were experimentally varied. In three preliminary experiments it was shown that: (1) when the cue nominally matched the signal in phase and intensity, it improved detection for frequencies below about 1200 Hz and was detrimental at frequencies above about 1400 Hz; (2) at 500 Hz, cue phase strongly affected detection performance, some phases resulting in performance much worse than without the cue; (3) at 500 Hz, the effect of cue intensity was small for the cue phase giving best performance (good phase), but increasing the cue intensity was detrimental to performance with a bad phase. With very loud cues, regardless of phase, performance declined with increasing cue intensity. The main experiment was a factorial study to examine the interactions of frequency, cue phase, and cue intensity. Phase was again found to be important at frequencies below about 1200 Hz, and to be more important the louder the cue. Worst performance at midfrequencies was found for the phase representing a cue lead of about 700 μsec. The phase and the related interaural time difference giving best performance were functions of both cue intensity and of cue frequency. No theoretical interpretation is attempted.
Most Comfortable Loudness for Pure Tones, Noise, and Speech
Authors: Ventry Ira M. , Woods Robert W. , Rubin Martha , Hill Wathina
Published: October 2005

Most comfortable loudness (MCL) levels for pure tones, broad- and narrow-band noise, and connected speech were studied in three independent experiments using Békésy audiometers and young normal-hearing males and females. Differences in MCL were explored as a function of attenuation rate, sex, frequency of the pure-tone and narrow-band stimuli, interrupted versus continuous pure-tone stimuli, instructional set, session, and a modified Békésy operation which allowed the subject to hold intensity constant over time versus standard Békésy operation. There were no significant sex, set, session, or operation differences. In all three experiments, a 2.5-dB/sec attenuation rate produced higher MCLs than a 1.25-dB/sec rate. In general, a 500-Hz tone or narrow-band noise centered at 500 Hz was tracked at the highest sound-pressure levels (SPLs), while broad-band noise was consistently tracked at the lowest levels. Regardless of frequency or attenuation rate, continuous pure tones were tracked at higher SPLs than interrupted pure-tone stimuli. Although intersubject variability was relatively high, the majority of test-retest differences in each experiment was 10 dB or less. Over-all MCLs in decibels SPL re 0.0002 μbar were 49.3 for speech, 49.4 for noise, and 51.7 for pure tones.
A Masking Noise with Speech-Envelope Characteristics for Studying Intelligibility
Authors: Horii Yoshiyuki , House Arthur S. , Hughes George W.
Published: October 2005

A noise whose amplitude envelope followed closely that of a concomitant speech signal was generated by multiplying white noise and the amplitude envelope of the speech, permitting the signal-to-noise (S/N) ratio to be specified on a short-time nonvarying basis. The spectrum of the amplitude envelope for continuous speech was studied, and the distributions of the vowel and consonant levels in articulation test materials were determined. Articulation functions in such noise and in continuous white noise were generated. Within the range of S/N ratios studied, the gains of the functions for vowels and consonants were 4% and 2.5% per decibel, respectively, in both types of noises. The results clearly depict the operational differences between conventional and envelope-noise S/N-ratio specification and suggest that use of the envelope-noise masker may eliminate some of the problems associated with current methods.
Perceptual Structure of 12 American English Vowels
Authors: Singh Sadanand , Woods David R.
Published: October 2005

Numerical ratings of dissimilarity among 12 American English vowels were analyzed by means of the Shepard-Kruskal procedure for nonmetric multidimensional scaling. The computer output was a geometric configuration of points representing the vowels whose interpoint distances related (approximately) monotonically to the dissimilarities data—the greater the judged dissimilarity between a pair of vowels, the greater the distance between the associated points. Using a procedure developed by Schönemann and Carroll, the axes from the MD-SCAL analysis were rotated, translated, and dilated to match a target “configuration” based on certain phonetic features. The dimensions from a three-dimensional analysis were interpreted as “tongue height,” “tongue advancement,” and “retroflexion” (multiple R = 0.70). When the vowel /ɜ/ was eliminated from the analysis, however, only the first two of these dimensions were needed (multiple R = 0.73).
Auditory Threshold at 125 Hz as a Function of Signal Duration and Signal Filtering
Authors: Karlovich Raymond S. , Lane Ronald H. , Smith Linda L. , Tarlow Arlene J. , Thompson David J. , Vivion Michael C.
Published: October 2005

Ten experienced listeners, eight males and two females, whose hearing sensitivity was within normal limits, participated in a study concerned with an assessment of auditory threshold for a 125-Hz stimulus as a function of stimulus duration and low-pass filtering of the test stimulus. Thresholds were obtained with a Békésy-type tracking procedure for six stimulus durations (5, 10, 20, 50, 100, 200 msec) in conjunction with three filtering conditions (unfiltered—UNFIL; 200-Hz low pass—LP-200; 150-Hz low pass—LP-150). Spectral analysis of the stimuli for each duration and filtering condition was performed. Temporal integration occurred for a 125-Hz stimulus during the LP-200 and LP-150 conditions but not when the stimulus was unfiltered (UNFIL). The LP-150 condition resulted in an average integration of 11.5 dB/decade between 5 and 200 msec and the average integration for the LP-200 condition was 8.6 dB/decade. Thresholds over the 5- to 200-msec range for the UNFIL condition did not vary by more than 1 dB, thus indicating the absence of temporal integration. It was inferred that temporal integration occurs for low-frequency stimuli when the spread of energy toward the higher more sensitive frequency region of the auditory area is limited by low-pass filtering.
Ultrasonic Examination of Proton-Transfer Reactions at the α-Amino and Side-Chain Groups of Arginine and Lysine in Aqueous Solution
Authors: Hussey Matthew , Edmonds Peter D.
Published: October 2005

Additional data are reported on the kinetics of proton-transfer reactions in aqueous solutions of amino acids to supplement previous work on glycine solutions. Ultrasonic absorption techniques were employed. It is concluded that the data do not satisfy a model based upon independent reactions at the α-amino and side-chain amino groups; consequently, some degree of interaction between these sites is deduced but is not quantified.
Experimental Investigation for Detection of Sound-Pressure Level by a Microphone in an Airstream
Authors: Nakamura Akira , Sugiyama Akira , Tanaka Tadami , Matsumoto Rimpey
Published: October 2005

Investigations were made to find a physical concept for evaluating the pressure level of sound that exists in an airflow by means of a wind screen or probe microphone. In order to provide a sound pressure in the airflow, sound of a known pressure level, which is assumed to be of higher level than the aerodynamically generated noise, was radiated into a duct from an external sound source. The output level of the microphone was measured for various differences between the sound-pressure level produced by the external sound source and the pressure fluctuation level of turbulence in the airflow. Results obtained agree with the superposed level of output by sound pressure and output produced by pressure fluctuation of turbulence. A new concept for characterizing microphone response to wind-flow fluctuation is presented. This characteristic is defined by the difference between the magnitude of the pressure fluctuation of turbulence and the output level of the microphone produced by the turbulence-fluctuated pressure, if aerodynamically generated noise is negligible. It provides a lower limit of sound pressure which can be detected by a microphone in an airflow. Moreover, the detection of noise generated by a grille in a duct is discussed by taking account of the characteristics of the microphone response to wind-flow fluctuation.
Thermoelastic Damping of Stress Waves Induced by Volumetric Energy Deposition
Authors: Stickler D. C. , Nickell R. E.
Published: October 2005

The effects of high-intensity electromagnetic energy deposition in solids can be catastrophic. Among the mechanisms which could be considered as thermal shock wave mitigators is the dissipative mechanism of thermoelastic damping. In order to assess this concept, a coupled linear one-dimensional thermoelastic problem with a volumetric heat input is solved by an approximate technique. The problem corresponds to the impulsive heating of a partially transparent (to radiative flux) medium. The approximate solution has the correct behavior for small and large times, satisfies the boundary conditions, and duplicates the behavior of the discontinuities in the field variables (in particular, the stress field). For parameters in the range of physical interest, the solution obtained here differs little from the uncoupled solution, with one exception. In this case, the effect of thermoelastic coupling is essentially to remove the discontinuities from the fields so that changes in the neighborhood of the wavefront are rapid but continuous. Failure criteria are essentially unaffected, since the peak tensile stress is very nearly the same for coupled and uncoupled solutions.
Dynamic Coupling of Elastic and Fluid Modes in an Infinite Elastic Plate in Contact with an Inviscid Liquid Layer
Authors: Walter W. W. , Anderson G. L.
Published: October 2005

The first five branches of the dispersion curves for straight-crested waves propagating in an infinite isotropic elastic plate, in a state of plane strain, that is covered by a layer of an incompressible inviscid liquid are determined numerically from the exact dispersion relation. Using the classical theory of flexure, the Mindlin theory of flexure, and the Kane-Mindlin theory of extensional motion in elastic plates, approximate dispersion relations are derived, and the effect of coupling between the flexural, extensional, and fluid modes is studied. Upon comparison of the exact and approximate results, it is found that the coupling of flexural and extensional motions arising through the velocity continuity condition at the liquid-plate interface is rather weak, so that good approximations to the fluid, flexural, and thickness-shear branches of the dispersion curves can be obtained by neglecting the coupling with the extensional and thickness-stretch branches. Furthermore, the extensional branch is not appreciably influenced by the coupling condition, and the thickness-stretch approximation is a good one in the low-frequency range only if the mass density of the plate is much greater than that of the liquid.
Cavitation Erosion of Aluminum at Elevated Pressure
Authors: Angona F. A.
Published: October 2005

An experimental investigation of the effect of hydrostatic pressure on cavitation erosion is described. A focusing acoustic system enclosed in a pressure chamber permitted the sound pressure and the hydrostatic pressure to be varied independently over the range of 1–20 atm. The intensity of cavitation, as measured by the erosion rate of aluminum, was found to grow at an increasing rate with hydrostatic pressure. Experimental results obtained in this pressure range correlate with published Russian data taken at pressures up to 75 atm. A correspondence between cavitation erosion and electromagnetic radiation is postulated. The agreement between experimental results and those predicted by this correspondence is quite good.
Finite- and Small-Amplitude Underwater Gas Bubble Oscillations Compared
Authors: Epstein David
Published: October 2005

Underwater gas bubble expansion as a function of the ambient-pressure to bubble-pressure ratio p′, in the interval 0⩽p′⩽1, is investigated. At the endpoints, a simple analytic solution to the nonlinear equations of motion in closed form may be found; but, for intermediate values of p′, an approximation is required. In the noncompressive case, representations suitable for large bubble radii, near p′=0, and small-amplitude motion, near p′=1, are derived. A result of this analysis is that the Willis bubble pulse formula, correct in the limit p′ → 0, in agreement with experiment, appears to be valid over much of the interval, but it starts to break down as p′ → 1. The power law governing finite- and small-amplitude periods is different; the actual period has no simple power law dependence, but may be deduced for all p′ by fitting a curve to the asymptotically correct values at p′=0 and p′=1, respectively. Owing to radiation and other loss mechanisms, bubble starting out as finite-amplitude pulsation, with a cusplike shape at the minimum, is gradually transformed into a small-amplitude damped sine wave; concurrently T1 → T̄. (Analysis in this paper refers to case γ = 43.)
A Digital System for Volume Reverberation Studies
Authors: Nickles J. C. , Johnson R. K.
Published: October 2005

An experimental apparatus has been developed as part of a continuing program of deep-sea acoustic-scattering research. It consists of a computer-based shipboard console and a cable-suspended package which contains the acoustic sources and receivers. The computer provides for preprocessing, recording, and display of the data, and for control of the experimental sequence. The sensor package operates at depths to 1600 m, acquiring scattering data for eight frequencies from 4 to 25 kHz.