bluuebunny/crossref_metadata_2025 huggingface dataset:
Digital System for Volume Reverberation Studies
Authors: Nickles John C. , Johnson Richard 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, as well as environmental parameters. [This report represents the results of research sponsored by the Office of Naval Research.]
Measurement of Time-Varying Spectra of Surface Reverberation
Authors: DeFerrari Harry A.
Published: October 2005

Observations of the CW acoustic propagation between a fixed source and receiver in the Florida Straits have revealed fluctuations in both phase and amplitude with frequencies corresponding to surface waves. Comparison of the spectra of acoustic phase and amplitude to the spectra of surface wave height show proportionally more energy in the acoustic signal in the frequency range of sea swell than in the frequency range of wind-driven waves. To investigate the effects of sound-speed structure and wind speed and direction upon the surface modulation, online digital processing has been employed. Phase coherent demodulation and filtering followed by fast Fourier transform provide nearly continuous spectra of the acoustic signal. A spectrum is obtained every 3 min with a frequency resolution of 0.005 Hz from ±0.5 Hz about the 420-Hz carrier. Three dimensional displays of frequency, intensity, and time are presented for several 2-h samples on selected days having varying conditions of wind speed and direction. The presented data are discussed in light of single reflection experiments (Roderick) and known seasonal characteristics of acoustic propagation in the Florida Straits.
Energy Conservation for Rough-Surface Scatter
Authors: Lynch P. J. , Wagner R. J.
Published: October 2005

The description of high-frequency scatter from random rough surfaces by the usual surface slope density formulation is internally inconsistent for, in general, energy is not conserved. Nonphysical energy losses are introduced by the neglect of multiple scatter and become more pronounced with increasing rms slope. Nonphysical energy gains arise from the neglect of shadowing considerations and tend to infinity at grazing incidence. These deficiencies in the theory are demonstrated for a perfectly reflecting, one-dimensionally rough surface. It is shown that the infinity at grazing incidence is removed by the extension of slope density to joint probability density of slopes and illumination. However, this modification is only the first term in a ray-trace expansion of the scattering coefficient in the number of surface interactions encountered by an incident ray. A numerical calculation of the shadow-consistent, single- and double-scatter terms demonstrates a significant reduction in the magnitude of the nonconservation discrepancies over the entire angular range, and a virtual elimination of these difficulties over an appreciable angular range about grazing.
Asymptotic Solution of the Stochastic Helmholtz Equation for a Continuous Fluid
Authors: Neubert J. A.
Published: October 2005

It is indicated that a two-variable asymptotic expansion is necessary for sound propagation in a continuous, weakly inhomogeoneous medium and that the Debye approximation is an acceptable and useful two-variable expansion. Its application to the stochastic Helmholtz equation yields, to order ασκ√Rt/λg2k02, the eikonal equation and the transport equation (where α is the rms refractive variation, σκ is the Prandtl number, Rt is the turbulent Reynolds number, λg is the Taylor microscale and k0 is the wavenumber); the resultant acoustic frequency limitations in turbulent air and turbulent water are developed and compared. The solution of the eikonal and transport equations in a continuous fluid leads to a Lagrangian pressure relation. Finally, the Debye and Born approximation are compared for one-dimensional sound propagation.
Frequency and Time-Domain Differentiation of Speech Contour Data for Voice Recognition
Authors: Snider Donald L. , Mergler Harry W.
Published: October 2005

In an attempt to enhance voice recognition capabilities, several transformations have been applied to the speech acoustical signal. The transformations include first- and second-order partial differentiation of the amplitude of the frequency-time-amplitude contour with respect to frequency and with respect to time, and variable segmentation of this contour and the derivative contours based upon criteria obtained from the partial derivative information. To provide the initial data base for the experiments, an instrumentation system was implemented to digitize the speech contours with the high degree of resolution of 256 frequency channels and 125 time increments or 32 000 data points. Computer-generated contour spectrograms were produced for the original contour and for the first and second partial-derivative contours. Speech recognition and speaker identification systems have been computer simulated to evaluate the effectiveness of the transformations.
Effects of Helium and Depth on Long-Term Speech Spectrum
Authors: Gerstman L. J. , Flower R. A.
Published: October 2005

Specifications of helium speech phenomena have been hampered by the limited amplitude range of sound spectrograms. This limitation has been overcome through use of a Federal Scientific Corporation UA-6 spectrum analyzer combined with digital averaging equipment, which together have permitted attainment of stable spectrums from textual passages as brief as the Pledge to the Flag. Comparison of sea level recordings with those spoken at depths up to 800 ft reveal confirmation of frequency multiplication according to a formula reported previously [L. J. Gerstman, G. R. Gamertsfelder, and A. Goldberger, J. Acoust. Soc. Amer. 40, 1283 (A) (1966)]; average amplitude suppression of 24 dB for speech frequencies between 1 and 3 kHz at sea level; no difference in these effects as between vowels and the noisy portions of fricative consonants. A breadboard device designed to reverse these effects has yielded intelligibilities of 88% and 78%, for monosyllabic words spoken at 500 and 800 ft, respectively. [Research supported by the Office of Naval Research.]
Time Domain Measurements for Speech Analysis and Recognition
Authors: Ito M. R. , Donaldson R. W.
Published: October 2005

At present, acoustical descriptions of speech sounds are usually given in terms of spectral characteristics, and spectral measurements are the usual form of data input for automatic speech recognizers. Measurements made directly on the acoustic signal are of interest as an alternate form of acoustical description and are potentially very useful in computer-based recognition schemes. A number of such measurements have been investigated. These include zero-crossing rate of the normal and differentiated acoustic signal, time interval between successive zero crossings for normal, low-passed, and high-passed versions of the acoustic signal, form factors of the waveform, and signal intensity Sound classes that have been studied include voiced and unvoiced fricatives, voiced and unvoiced stops, and vowels. Present results indicate that in comparison with spectral measurements: (a) rapid sequential features are better preserved; (b) the measurements are less sensitive to intensity fluctuations; (c) unvoiced fricatives and stops are easily characterized; (d) vowel resolution appears to be comparable. Application of these results to spoken word recognition is considered.
Acoustical Analysis of the Consistency of Baby Cry Patterns
Authors: Massengill Raymond , Royster Larry
Published: October 2005

Research studies have been conducted in the past concerning different aspects of baby cries, but a perusal of the literature failed to reveal evidence showing extensive research done with consistency of baby cry patterns. In the present investigation, magnetic tapes were utilized to record cries of babies. The original tapes were played back utilizing a Sony, Model TC-530, tape recorded and simultaneously monitored utilizing a Tektronix Oscilosocope, model 545, and a Brüel & Kjaer Graphic Level Recorder, type 2305. The purpose for monitoring the various tapes was to eliminate any cries that had been clipped by the recording procedures or system and those cries during which a baby coughed or seemingly became strangled. Once these cries had been identified, then in a random manner two cries were selected from each subject and recorded utilizing a general Radio Data Recorder, model 1525-A. Tape loops were then formed in order to be able to conduct a 1-oct and a 113-oct analysis of the cries. A statistical analysis was conducted and the results of the study are reviewed.
Analysis of Fundamental Frequency Contours
Authors: Levitt H. , Rabiner L. R.
Published: October 2005

Many factors contribute to the variability of measured fundamental frequency 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. One method for analyzing such data is to subdivide the time scale into a series of time windows and to approximate the 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 may also be 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 variations in degree of variability at different times during the utterance, but also allows the investigator to approximate families of fundamental frequency contours to any prescribed degree of precision using a minimum least squares criterion. Substantially fewer coefficients were required to parameterize the measured fundamental frequency contours during the stressed portions of an utterance than during the nonstressed portions.
Speech Analysis Using An Analog Cochlea
Authors: Mundie J. Ryland , Moore Thomas J.
Published: October 2005

Three dimensional representations of speech have been produced by an electronic model of inner ear function. These surfaces represent the temporal motions of the basilar membrane driven by speech signals. A previous paper from our laboratory pointed out that distinctive features of these surfaces can be used to identify various vowels and voiced consonants independent of speaker. This paper reports on measures of the distance between the first two peaks that occur in surfaces of single glottal pulses. The measurements are made at three locations along the length of the basilar membrane. They are sufficient to identify vowels and transitions that occur in the vocal tract during diphthongs can readily be followed.
Subliminal Sensitization Effect
Authors: Brandy W. T. , Cooper W. A.
Published: October 2005

Eight normal-hearing male observers were trained to detect brief acoustic pips during a YES-NO procedure until a consistent correct-response rate of approximately 80% was achieved. The pips were presented to one ear at an equivalent level during reference, control, and experimental conditions. During the experimental conditions, the pips were presented at 90° re an on-going 50-Hz sinusoid, which was presented ipsilaterally at four subliminal levels (−10, −20, −30, and −40 db SL). Utilizing a balanced design, four observers received the signals in the right ear and four received them in the left. Higher correct-response rates were observed when the 50-Hz sinusoid was presented at −10 and −20 dB SL than during any of the other conditions. This increase in the correct-response rate for the pips in the presence of a subliminal 50-Hz sinusoid was called the Subliminal Sensitization Effect (SSE). When the effect of level was evaluated, it was noted that the SSE broke down when the 50-Hz sinusoid was between −20 and −30 dB SL. Analyses of group differences revealed a greater SSE for the observers who received the signals in the right ear.
Parallel Channels Models of Auditory Detection
Authors: Katz A. , Zambuto M.
Published: October 2005

Several models of the auditory system in which the signal flows along parallel channels were investigated. Some of the models studied exhibit nonlinear lateral interaction between channels. The effects of both single and multiple formant excitation and of intrinsic noise were considered. Performance was evaluated in terms of the signal-to-noise density ratio corresponding to a desired probability of correct detection given the presence of such signals for varying constraints on system information capacity, bandwidth, and complexity. Of particular significance to the analysis was the adoption of a fixed false-alarm rate (Neyman-Pearson relation) in favor of the common Bayes Criterion. A series of psychoacoustic tests were conducted, and the results of these tests, as well as published results by other investigators, were compared to the performance of the model. The data indicate that parallel-channels models in general exhibit excellent noise performance and that, when used in conjunction with lateral interaction, they can successfully model many psychoacoustical phenomena.
Two Distinct Loudness Functions of the Ear
Authors: Young I. M. , Wenner C.
Published: October 2005

A binaural loudness balance was performed using subjects with normal hearing. The reference signal was a pulsed tone, and the balance signal was a steady tone of the identical frequency. The reference tone was presented at intensities of 20, 40, 60, and 80 dB re 0.0002 μbar. The balance tone consisted of a continuously varying intensity (increasing or decreasing) having an attenuation rate of 1, 2, 4, or 8 dB/sec, whose starting intensity was either suprathreshold or infrathreshold. As was anticipated, the different attenuation rates modified the balance point with the closest balance occurring with the use of 8 dB/sec attenuation rate. Suprathreshold starting intensities presented a poorer balance (balance at higher intensity) than did the infrathreshold starting intensities. An unexpected result was the differentiation of the balance levels of the supra- and infrathreshold starting intensities when compared with the various attenuation rates. A balance signal starting from below threshold gave results having a logarithmic relationship to attenuation rate, whereas a starting intensity above threshold yielded balance points having a linear relationship to that of the attenuation rate. It would appear that there are two distinct characteristics in the ear that are dependent upon the starting intensity to which the ear is exposed before performing a particular function.
Transitivity of Loudness Level
Authors: Gerber Sanford E. , Milner Paul
Published: October 2005

In mathematics, the law of transitivity states quite simply that if A = B and if B = C, then A =C. The question of whether the law of transitivity holds for loudness level was investigated in this study to confirm an observation made in a previous report without adequate proof. [B. B. Bauer and E. L. Torick, “Researches in Loudness Measurement,” IEEE Trans. Audio Electroacoust. AU-14, No. 3, 141–151. A panel of eight women were presented octave bands of pink noise from 125 Hz to 250 Hz to 2 kHz to 4 kHz, known to be at 70 phons loudness level, referred to a 13-oct band of pink noise centered at 1 kHz. They were asked to compare the loudness of any octave band to each of the other bands also at 70 phons until all were compared. The stimuli were presented through a loudspeaker in a listening room with known acoustical properties. The results indicate that loudness level is indeed transitive. An analysis of variance is performed on the data to support the findings.
Damping Factor of Light-Weight Walls
Authors: Angevine O. L. , Isada Nelson M.
Published: October 2005

Cremer has shown that the damping factor of walls, the ratio of the imaginary to the real portion of their complex stiffness, is important in determining the sound transmission loss that a wall may afford above the frequency of coincidence of the trace of the acoustic wavelength upon the wall and the wavelength of the wall's flexural vibration. Measurements were made for several gypsum-board and steel-stud wall constructions. Many of these showed a constant value of the damping factor, but walls having fibrous insulation between studs or having a layer of wood fiberboard under the gypsum board showed an increased value of damping factor as the frequency was reduced below 4000 Hz. The measured value of damping factor was used to calculate the transmission loss and good agreement with measured TL was found.
Calculation of the Impact Noise Isolation of Composite Floors
Authors: Ver Istvan L.
Published: October 2005

This paper describes a procedure for calculating the impact-noise level of the sound that would be radiated by a bare, stiff structural floor into the reverberant receiving room below, when excited with a standard tapping machine. Calculations are also given for the improvement in impact noise isolation achieved by adding: (a) an elastic surface layer, (b) a locally reacting floating floor, and (c) a resonantly reacting floating floor, to the structural floor.
Sound Isolation Criteria for University Dormitories
Authors: Curtis J. A. , Hirtle P. W.
Published: October 2005

Five existing dormitory buildings at a large eastern U. S. university were surveyed in order to establish acoustical criteria for the university's campus housing building program. Objective acoustical measurements were made in each of the facilities, including background noise levels and noise reduction of walls, floors, and doors. In addition, subjective data were obtained distribution of questionnaires, which were returned by more than 600 students. Correlation of the subjective responses with the objective data is consistent with previously reported results on dormitories [J. A. Curtis and W. J. Cavanaugh, J. Acoust. Soc. Amer. 35, 787 (A) (1963)]. Sound isolation criteria are proposed for university level dormitories and construction guidelines are presented.
Comparison of the Aircraft Noise Reduction Achieved in Modified Houses in the United States and England
Authors: Bishop Dwight E.
Published: October 2005

Recently, five houses in three localities were modified in different ways to achieve more effective reduction of aircraft noise. (Results of modifications to two houses in Los Angeles were reported at the previous meeting.) The noise reductions achieved in the six rooms most extensively modified are compared with the noise reduction reported for 15 rooms in England. [W. E. Scholes and P. H. Parken, “The Insulation of Houses Against Noise from Aircraft in Flight,” J. Appl. Acoust. 1, 37–46 (1968)]. The average noise reduction achieved in both the United States and English houses is quite similar. This leads to a tentative conclusion that the observed noise reductions for these modified rooms approach the maximum that can be achieved without very elaborate house modifications involving extensive changes in existing wall and roof constructions. [Studies supported by the Department of Housing and Urban Development.]
Bowed Violin String is Perfect
Authors: Kohut J. , Mathews M. V.
Published: October 2005

The velocity of a bowed violin string was measured at various points along its length and at various bowing positions by placing a magnetic field perpendicular to the string and observing voltage induced in the string. The string was found to oscillate in a simple triangular pattern described by Rayleigh, which is a normal mode of the unbowed string. Thus the bow simply serves to replenish the energy lost during the vibrations. At the bowing point, the ratio of flyback time to the period of oscillation equals the ratio of bridge-to-bow distance divided by string length. Larger amplitude motion can be achieved either by bowing faster or closer to the bridge. A digital computer solution of the string motion was carried out and agrees with the observed data. In addition, it showed aberrations in the waveform that occur if the bow is at a node of a harmonic of the period. This implies that a violinist avoids bowing exactly at a node of a low harmonic.
Characteristics of Moving In-line Receivers
Authors: Eichler Ewald
Published: October 2005

A number of phenomena characteristic of linear additive arrays are analyzed that are related to the Doppler shift experienced by a moving point receiver. Directional response changes with the velocity of motion. It is found that simple adjustment of delays (“speed tuning”) can optimize a response maximum but cannot maintain fixed the entire directional pattern. The response to isotropic background noise at any received frequency and also, in consequence, the gain becomes dependent, in motion, upon the spectrum of the reference noise field. It seems recommendable to characterize receiver noise, inclusive of flow noise, in terms of the spectrum of an equivalent plane wave of equal received frequency and thought incident in the preferred direction. Calculations are presented for continuous endfire-line receivers and for back-nulling gradient-type receivers at subsonic and also at supersonic velocities of motion. [Supported by the Office of Naval Research, Acoustics Branch.]
Residue Pitch as a Function of the Number and Relative Phase of the Component Sinusoids
Authors: Patterson Roy D.
Published: October 2005

Schouten, Ritsma, and Cardozo (1962) measured the pitch of the residue as a function of the frequency region of a three-component stimulus. In an experiment extending this work, the pitch of the residue was measured as a function of frequency for signals composed of either six or twelve sinusoidal components. The components of a complex were either all in cosine phase or all in random phase. In both this and Schouten's experiment the frequency spacing between adjacent components was 200 Hz. We found that stimuli whose lowest frequency components are identical give rise to the same residue pitch. Neither the number of components, three, six, or twelve, nor the relative phase of the components are important in determining the pitch of the residue. [Research supported by the National Institute of Health, Public Health Service, U. S. Department of Health, Education, and Welfare, and by a research grant awarded to the Center for Human Information processing.]
Pitch Discrimination Subsequent to a Variable Time Delay
Authors: Thomas Ian B. , Nicola Paul Di , Elia Michael , Pasierbiak Carl
Published: October 2005

Fifty listeners heard stimuli consisting of two equal amplitude pure tones (A and B) in sequence followed by a silent period of variable duration T and finally a pure tone X equal in frequency and amplitude to either A or B. The task of the listeners was to decide if the delayed stimulus X corresponded to A or B. The duration of each of the segments A, B, and X was 1.25 sec throughout as was the duration of the silent interval between tones A and B. The duration of the silent interval T ranged from 5 to 110 sec. Pairs of tones of frequencies 500 and 550 Hz, 1000 and 1100 Hz, and 1800 and 1980 Hz were employed. The pair used, the order within pairs, and the order with which variable delays were presented were all randomized. A tape of all stimuli including delays was prepared prior to the experiment; listeners heard the stimuli binaurally in phase at around 80 dB SPL (0.0002 dyn/cm2). Listeners obtained near perfect scores (>90%) for values of T up to 20 sec. Scores then dropped abruptly to about 68% and maintained this level until a value of T of approximately 65 sec at which time scores fell below the 5% significance level (score of 61%) for this test. Work is continuing on tones separated in frequency by values other than 10%. [Work supported by NIH.]
Variations in Two-Tone Masking Paradigms
Authors: Brandt John F. , Booth John C.
Published: October 2005

The traditional two-tone masking technique typically uses a sinusoid or a narrow-band noise as a test signal located at a fixed, specified frequency, midway between two sinusoids. The masked threshold of the test signal is measured as the frequency separation between the maskers is varied in discrete steps. The present study generated the two-tone masker by modulation techniques. The frequency separation between the maskers were varied in discrete steps and also continuously with similar results. When the entire stimulus complex was swept over the audio range, as in the Booth and Brandt study, the threshold data with respect to critical band hypotheses became very complex. Implications of these procedural differences are discussed.
Transient Wave Propagation in a Transversely Isotropic Rod
Authors: McNiven H. D. , Mengi Y.
Published: October 2005

The response of a semi-infinite, transversely isotropic rod to a time-dependent input on the end of the rod is found using the method of characteristics. The rod is of circular section and the material of the rod is arranged so that axes of isotropy are parallel to the axis of the rod. To reduce the problem to one where motions depend on only one space variable and time, an approximate theory is developed, which is a three-mode theory and which is valid for an extensive frequency range. Numerical results are found for an input that has a step distribution in time and for two different materials, magnesium and a fiber-reinforced material. For each material, the response is found in terms of four quantities—radial strain, axial strain both on the lateral surface and along the axis of the rod, and the generalized stress.
Nonmodal Solution to a Cylindrical Shell Problem
Authors: Feit D.
Published: October 2005

When dealing with the vibrational response of structures, the classical modal type analysis is quite adequate for low-frequency vibration problem. With increasing frequency, the modal analysis becomes more difficult to numerically evaluate owing to the slow convergence of the sums. Using a Sommerfeld-Watson type transformation [D. Feit and M. C. Junger, J. Appl. Mech. 36, 859–864 (1969)], the modal sum for the response of a point-excited cylindrical shell is converted to a sum consisting of a finite number of terms. Each of these terms can be interpreted in terms of the flexural wavefield of a point-excited infinite flat plate. [Work supported by the Structural Mechanics Branch of the Office of Naval Research.]
Closed-Form Solution of Forced Vibrations of Spherical Shells with Attachments
Authors: Junger M. C.
Published: October 2005

The forced vibrations of a finite elastic system can be analyzed as a superposition of normal modes or as waves in an infinite waveguide with reflecting discontinuities. The latter leads to a closed-form display of the solution [e.g., for strings, P. M. Morse, Vibration and Sound (McGraw-Hill Book Company, New York, 1948), 2nd ed., pp. 94–95]. This technique is applicable to systems whose normal modes are not known [e.g., coupled beams, J. C. Snowdon, Vibration and Shock in Damped Mechanical Systems (John Wiley & Sons, Inc., New York, 1969), pp. 230–239]. This waveguide formulation is illustrated here for spherical shells coupled to arbitrarily located spring-mass systems. The response of this composite system is constructed by matching the oscillator impedance to the shell impedance formulated in terms of the closed-form solution of the homogeneous shell [D. Feit et al., J. Appl. Mech. 36, 859 (1969)]. Because conventional methods (modal expansions, computer methods) are laborious for structures measuring many flexural wavelengths, the waveguide solution is specialized to these conditions, i.e., to the high-frequency range. [Supported by Office of Naval Research, Structural Mechanics Program.]
Variational Techniques in Acoustic Radiation Theory
Authors: Rogers Peter H.
Published: October 2005

The possibility of applying variational methods to the acoustic radiation problem for an arbitrary body with a given velocity distribution is investigated. It is found that since the stationary quantity involved is, in general, neither a maximum nor minimum, the variationally determined result may not always be accurate. Sufficient conditions for achieving accurate results are determined. Since there is no way of knowing a priori, whether for any given problem these conditions will be satisfied, methods must be devised which ensure and/or give a measure of the reliability of a given calculation. Several possible approaches are indicated, some which yield a quantitative measure of the accuracy of the results. It is found that these variational methods, although based on the surface Helmholtz integral formulation, are applicable even at characteristic wave numbers and, hence, may provide an attractive alternative to the CHIEF program. A simple example illustrating the use of one of these techniques is presented.
Humanization of Computer Music
Authors: Smith Leland
Published: October 2005

In most computer music, rhythm has been expressed in real-time seconds. Some flexibility has been achieved by using sub-routines that change the input seconds to varying real durations. The Stanford Computer Music Program Group now includes many features that make it possible to approach rhythm from a musician's point of view. Strict rhythm may be entered from a teletype using either real-time values or a completely musical terminology with no limits on complexity. A supplementary program, RHYTHM, has been written that may be used in several ways. RHYTHM reads real-time input from two telegraph keys. In the simplest case, the specific durations read from the keys are used to replace typed in musical values. Human error and expressive need lead to acute problems when several individual parts are to be coordinated. The main notation program, SCORE, allows the musician to specify at exactly what points each part will be coordinated with the mainstream of the music. After the separate parts are prepared, RHYTHM may be used to “conduct” the entire piece. Each part retains its individual character while at the same time following all nuances of the conductor's beat.
Whisker Reinforced Piezoelectric Ceramic Transducer Material
Authors: Lester William W. , Whymark R. R. , Shaver R.
Published: October 2005

The present paper concerns the successful production of whisker-reinforced composites of the piezoelectric ceramic type. Specific results are presented concerning the composite properties of α-Alumina (sapphire) whiskers in a lead zirconate titanate matrix. Other whisker and matrix materials are briefly discussed. In general, the process of adding whiskers to the piezoelectric matrix results in a new material with somewhat different properties, yet one that remains piezoelectric. Specific details discussed include the measurement of dielectric constant, dielectric loss tangent, electromechanical coupling factor, mechanical Q, density, and modulus for a number of whiskered piezoelectric samples. Data on appropriate parameters are presented as a function of temperature over a wide range. The indication is that the addition of whiskers to the material pins the domains so that a “harder” material is produced. The result is a higher Curie temperature for the composite than the matrix alone, a higher poling temperature, a lower dielectric constant, and other related changes. The activation energy for domain wall motion is determined for the matrix material but gives difficulties in the composite case. [Supported by the Office of Naval Research.]
Influence of Macrosonics on Some Processes: Corrosion, Liquid Flow, Drying
Authors: Fairbanks H. V.
Published: October 2005

The introduction of macrosonics into air-heated specimens of cast iron and steel substantially decreased the rate of corrosion. Microscopic examination of the specimens showed that a thinner and more compact film had been formed by insonation. The flow of oil and water through a porous medium was stimulated by the introduction of macrosonics into the system. Sandstone and a porous stainless-steel filter were used as the porous medium. The drying of fine coal powder was aided by the introduction of macrosonics. Frequencies of 12 and 20 kHz were used.
Measurements of Mode Attenuation Coefficients in Shallow Water
Authors: Ferris R. H. , Faber A. L. , Ingenito F.
Published: October 2005

An experiment was conducted in the Gulf of Mexico to evaluate a technique for measuring modal attenuations. Use of short pulses allowed individual normal modes to be observed and then identified by comparing observed pressure distributions and arrival times with those predicted by a normal mode model. Variable depth sources for 400, 750, and 1500 Hz were mounted on a fixed platform. A vertical string of hydrophones was suspended from a ship, which anchored at several ranges. The measurements were made under downward refracting conditions in 30 m of water with a level sand bottom. For the first two modes at 400 Hz, vertical pressure distributions, relative arrival times and time spreading due to dispersion were in good agreement with theory. Higher modes and modes at 750 Hz and 1500 Hz were not identified. By comparing peak amplitudes at different ranges, a mode attenuation coefficient of 1.3 dB/km was determined for the first mode at 400 Hz.
Normal-Mode Solutions for Arbitrary Sound Speed Profiles
Authors: Cybulski John , Ingenito Frank , Newman Alfred V.
Published: October 2005

A computer program has been developed to provide a normal-mode solution of the wave equation with the sound profile for the medium represented by a set of discrete values. The sea bottom is assumed to be a semi-infinite fluid, specified by a constant density and a constant speed of sound and with no attenuation. The interface between the water column and the bottom is flat and level. The eigenvalues are obtained by an iterative procedure from a finite difference equation approximation. The program was utilized to develop the normalized eigenfunctions and group velocities for several idealized sound speed profiles. In addition, the program was used to provide information prior to and during an experiment in 30 m water off Panama City, Florida. Outputs included the normalized eignefunctions or mode shapes and the group velocities over a range of frequencies from 300 to 1700 Hz. This program was experimentally validated at the low frequencies and for low-order modes.
Intensity Fluctuations in a Stochastic Medium
Authors: Lord Norman W.
Published: October 2005

A representation of the ocean medium as a stack of very thin isosound velocity layers, stochastic in a part of their sound velocity, has been used to calculate the statistics for sound-intensity variation without introducing a random phase approximation. A model previously introduced [N. W. Lord, J. Acoust. Soc. Amer. 46, 111 (1969)] to calculate transmission-time statistics was extended first to treat intensity of discrete arrivals, quantitatively including phase differences among microarrivals, and second to accumulate at discrete range points all discrete arrival contributions similarly calculated and quantitatively including their mutual phase differences. Both discrete arrival intensities and accumulated or CW intensities show a Poisson-like distribution with standard deviation being equal to the mean for moderate sound velocity variance in rough agreement with existing data.
Selective Listening for Temporally Staggered Dichotic CV Syllables
Authors: Kirstein Emily
Published: October 2005

When CV syllables are presented dichotically with brief interaural delays, two effects are observed: (1) the delayed syllable is more accurately identified than the leading syllable (“lag” effect), and (2) syllables arriving at the right ear are more accurately identified than those at the left ear (“laterality” effect). The present study assesses the influence of manipulations of selective attention on the lag effect and laterality effect. Synthetic CV syllables contrasting only in the initial consonant (/b/. /d/, or /g/) were delivered over headphones. one syllable to each ear, with interaural delays of 10, 30, 50, 70, or 90 msec. Each subject performed two tasks: (1) attending to a particular ear and (2) attending to the temporal order, reporting either the leading or lagging syllable as instructed. Most subjects showed lag effects and right-ear effects in both tasks at all values of interaural delay. The nature of the task, ear monitoring or temporal order monitoring, did not influence the size of the lag effects and laterality effects of individual subjects. [Supported in part by NICHD.]
Role of the Pinna in Monaural Sound Localization
Authors: Gatehouse R. W. , Oesterreich R. E.
Published: October 2005

According to recent evidence, the pinna transforms sound in a way that permits humans to achieve relatively accurate monaural localization. In this study, normal cats were trained to select one of two movable food boxes using sound localization cues. A pulsed noise source was located behind one of two cloth covered food boxes. Accuracy of localization was measured initially and after each experimental manipulation: (1) surgical destruction of one cochlea, (2) partial or complete removal on the side of the intact cochlea, and (3) occlusion of the functional external auditory meatus. Eighth-nerve recording and histological analyses were performed to determine the success of the cochlear destruction. The results showed that monaural cats localize at least as well as binaural for sources near the midline, and that pinna removal does not affect this ability whereas occlusion of the meatus does. Further, the external auditory meatus may perform important transformations in the cat.
Frequency Discrimination in the Goldfish (Carassius auratus)
Authors: Fay R. R.
Published: October 2005

Using the classically conditioned suppression of respiration response, an audiogram for large, restrained goldfish was determined from 30 to 2400 Hz. Sound was generated into a closed air chamber above the water surface to minimize the nearfield effect. Frequency difference limens (DLs) were then determined by the same method at 50, 100, 200, 400, 600, 800, and 1000 Hz. All stimuli were presented at 35 dB above threshold. The lowest absolute threshold occurred at 350 Hz at about −35 dB/dyn cm−2. The audiogram rises slightly below 200 Hz, but steeply above 1000 Hz at about 24 dB/oct. The frequency DLs increase from 3.5 cycles at 50 Hz to 47 cycles at 1000 Hz. Expressed as Weber fractions, the best discrimination occurs at 400 Hz (0.037). The DL increases as two power functions of frequency. Below 400 Hz the exponent is 0.7, while above 400 Hz the exponent is 1.23. These two power functions suggest two processes of frequency analysis. Although man is an order of magnitude more sensitive, the DLs for both man and fish are two power functions of frequency, and the slopes of the goldfish curves are identical to the slopes of the curves for man.
Noise-Induced Permanent Threshold Shifts and the Equal-Energy Hypothesis in the Chinchilla
Authors: Ward W. Dixon , Nelson David A.
Published: October 2005

In a test of the equal-energy hypothesis, four groups of four chinchillas each were exposed to noise for 4 h at 114 dB SPL, 2 h at 117 dB, 1 h at 120 dB, and 30 min at 123 dB, respectively. The noise spectrum was designed to produce the same permanent threshold shift (PTS) at 1, 2, 4, and 8 kHz. There were no significant differences among groups in the average PTS produced (approximately 40 dB), thus confirming the earlier result of Eldredge and Covell [Laryngoscope 68, 465 (1958)] concerning the applicability of the equal-energy hypothesis to single high-intensity exposures in guinea pigs. However, it is stressed that these results do not permit us to conclude that the relation also holds for intermediate noise, or that risk of damage can be cumulated from day to day and week to week. [Supported by the National Institutes of Health, U. S. Public Health Service, Department of Health, Education, and Welfare.]
Frequency Response Characteristics of the Human Auditory System and Perceived Noise
Authors: Dunn S. E. , Hart F. D.
Published: October 2005

A modified approach for predicting the response of the human auditory system to noise is presented. The annoyance response of the human auditory system, defined as perceived noise, resulting from an excitation phenomena, described in terms of its measured SPL spectrum, is shown to be predictable through the application of the excitation spectrum to the frequency response mechanism of the system model derived in the report. Thus, the human auditory system is viewed as an input-output type of mechanism with the effects of variations in excitation levels and frequency characteristics being clearly discernible. It is shown that this model is obtained through the combination of existing and widely accepted concepts concerning the phenomena of masking along the basilar membrane and the contours of equal noisiness. In order to inspect the validity of the procedure, a number of excitation spectra are applied to its frequency-response mechanism. The resulting perceived noisiness predictions by the model are compared with evaluations based on previously published works on the subject of annoyance analysis. The findings obtained through the use of this new model are found to be consistent with those previously presented in the literature. [This work was completed under the support of NASA, Langley Field, Virginia.]
Effects of Exposure to Intense Low-Frequency Tones on Hearing and Performance
Authors: Smith Paul F. , Harris M. S. , Russotti J. S. , Myers C. K.
Published: October 2005

Groups of men were exposed for a 24-h period to either 70-Hz tones at 112.8±10 dB re 0.0002 dyn/cm2 or 300-Hz tones at 113.4±3 dB re 0.0002 dyn/cm2. During the exposure, performance on a sensory-motor task (“RATER”) was tested periodically, and auditory threshold shifts were measured. No decrement in RATER performance was noted for either group. TTSs were moderate except for one subject. The general behavior of the groups and statements made during informal interviews indicated that similar exposure conditions would be well tolerated on a routine basis.
Some Aspects of Spatial Perception with Reference to Open-Plan Offices and Schools
Authors: Osmond Humphrey
Published: October 2005

Work in psychiatric hospitals and in cultural anthropology has shown that the quality of space and the way it is organized influence the behavior of the people within this space. Cultural anthropology has shown that different cultures use space differently. It is therefore important to speculate as to what intended or unintended consequences may arise in the change from closed offices and classrooms to open-plan and whether these changes may be helpful or harmful to the goals of the particular enterprises concerned.
Hydroacoustic Power Conversion
Authors: Bouyoucos J. V. , Wise B. A.
Published: October 2005

Hydroacoustic power conversion is the controlled generation of acoustic or vibratory energy from hydraulic power. Basic concepts of high-power self-excited hydroacoustic vibration generators are described, the envelope of interest covering frequencies ranging from the subsonic region to the kilohertz region, and power levels extending in some instances to several thousand horsepower. A variety of equipment configurations are set forth that illustrate ways in which the vibratory energy obtained from the power conversion process may be coupled to loads to do useful work. These illustrations include high energy-density radiation of liquid media, high acceleration of massive loads, and high repetition rate impact loading of materials. Where appropriate, comparisons will be drawn to other means for accomplishing the same task. A short movie will be shown illustrating the embodiment of the concepts in an engineering model hydroacoustic rotary percussion rock drill and pile driver. Finally, an assessment of the current status of hydroacoustic technology will be given.
Effective Duration of Sound from a Moving Source
Authors: Young Robert W.
Published: October 2005

Effective duration and time-integrated noise level (exposure level) of the sound of a passing vehicle as measured at a point on a sideline, are modified by directionality of the sound source. The factor of proportionality between the effective duration and ratio of slant range to speed is shown to include the integral of the directivity pattern of the source. Since the effective duration increases in proportion to the minimum slant distance and inversely as vehicle speed, the (time-integrated) noise exposure level is reduced only 3 dB by each doubling of distance and doubling of source speed. Average (rms-equivalent) sound level, during a period such as an hour, is equal to the total integrated sound level over the hour minus the duration allowance, 10 log (3600 sec/1 sec) = 35.6 dB. Hence, in contrast to maximum noise level that decreases 6 dB with doubling of distance (plus absorption), average noise level from a single moving source decreases only 3 dB for each doubling of distance of closest approach. A routine is described for obtaining the time-integrated noise level of a single flyover or the average (rms-equivalent) sound level from a record of sound level versus time for the times that selected levels are exceeded.
A Cinefluorographic Study of the Emphatic-Nonemphatic Feature in Arabic as a Correlate of the English Tense-Lax Feature
Authors: Ali Latif H. , Daniloff Raymond
Published: October 2005

Previous investigations [Klatt and Stevens, “Pharyngeal Consonants,” QPR 93, 207–216 (1969)] show that there are well-defined places of articulation with distinctive acoustic properties which take place when the vocal tract constriction is made within the regions between the velum and the glottis. These sounds are traditionally known as emphatic and are found in the Semitic languages, in particular, Arabic. The high-speed cinefluorographic films made of three native speakers of Arabic answer several questions concerning the fine details of physiological activities which involve the tongue root with respect to the velum and the interior pharyngeal wall during articulating certain sounds, namely the emphatic and their nonemphatic counterparts in Arabic. The study also investigates the timing differences for other major articulator movements which serve to differentiate classes of sounds. [This project was supported, in part, by a Public Health Service research grant, the National Institute of Dental Research.]
Influence of Forced Transglottal Pressure Changes on Vocal Fundamental Frequency
Authors: Hixon Thomas J. , Klatt Dennis H. , Mead Jere
Published: October 2005

Forced transglottal pressure changes (ΔPt) were produced in 10 subjects while they sustained vowels and uttered monosyllables. Pressure changes were applied sinusoidally at both the body surface (subglottally) and the airway opening (supraglottally) by loudspeakers driven at 4–6 Hz (the empirically determined resonant frequency of each subject). Vocal fundamental frequency (f0) was recorded with a throat microphone and analyzed from narrow-band spectrograms. Results showed values for (Δf0/ΔPt) to be dependent upon vocal frequency, intensity, and register, and to be independent of vowel, voice quality, utterance type (i.e., sustained vowels versus vowels in syllables), and mode of applying pressure. Except for falsetto phonations, (Δf0/ΔPt) values exceeded 5 Hz/cm H2O in only one subject and in the speech range of f0 they were typically 2–4 Hz/cm H2O. These findings fail to support earlier work (Lieberman et al., 1969) based on one of the subjects included here. We conclude that f0 changes characteristic of conversational speech can be accounted for only in part on the basis of changes in (Pt) and that significant control of f0 is vested in laryngeal adjustments.