bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Head and Air-Leakage Sidetone during Monaural-Telephone Speaking
Authors: Noll A. Michael
Published: September 2005

It has been observed that low-level sidetone has less effect on vocal level than higher sidetone levels. Recent investigations reported in this letter show that this nonlinearity is caused by neglecting the effects of head and air-leakage sidetone in the measurements of the sidetone level. When these effects are included, a linear relationship between vocal level and sidetone level is obtained.
Component Characteristics for an Active Ear Defender
Authors: Meeker Willard F.
Published: September 2005

Proposed methods of electronic noise reduction at a listerers ears have been described previously [J. Acoust. Soc. Am. 28, 773 (A) 1956)]. A headset incorporating electronic noise reduction has been termed an active ear defender. One method proposed uses a microphone under each earphone in a negative feedback arrangement. Another method makes use of a microphone located outside the earphone cushion to provide a canceling signal. The canceling arrangement is very sensitive to amplitude and phase errors. Examination of its electrical analog reveals that a surprisingly large band width is necessary because of the critical phase requirements. The band width required for the negative feedback arrangement is also large but amplitude and phase characteristics within the useful band are less critical. In this paper the microphone and earphone characteristics required for effective noise reduction are discussed. A negative feedback system is described which provides approximately 15 db of noise reduction from 100 to 200 cps. Component characteristics which will make possible greater amounts of noise reduction are discussed. (Work supported by U. S. Air Force and U. S. Army Signal Corps.)
Reverberation under Arctic Ice
Authors: Brown J. R.
Published: September 2005

Reverberations from detonators exploded under Arctic ice were recorded in the octave bands 1.28–2.56 and 5.12–10.24 kc/sec. The measurements were made from a polar floe during 4–6 September 1963 in Prince Regent Inlet near 73°N and 91°W. The resultant scattering strengths were similar to those obtained by Chapman and Harris from recordings of reverberations made in the open sea in 30-knot winds.
Reflection of an Underwater Shock Wave from an Overlying Ice Layer
Authors: Green Robert E.
Published: September 2005

Theoretical consideration is given to the problem of reflection of a shock wave in water from an overlying ice layer. Expressions are derived for the sound field in the ice, in the water, and in the bottom.
New Display Format and a Flexible-Time Integrator for Spectral-Analysis Instrumentation
Authors: Wood David E.
Published: September 2005

Continuing development has increased the capabilities of the spectral-analysis instrumentation reported earlier [D. E. Wood and T. L. Hewitt, J. Acoust. Soc. Am. 35, 1274–1278 (1963)]. This analyzer operates in real time by very rapid scanning of the outputs of a bank of bandpass filters. A unique process of true interpolation generates continuous spectral cross sections that preserve accurate frequency relations of signal components. The cross sections are recorded on strip film by photographing their display on a CR tube. Spectrographic-picture formats previously described include complete cross-section records and spectrograms showing amplitude by intensity-modulation. A new display technique clarifies frequency patterns by marking just at the amplitude maxima or “peaks” in spectral cross sections. The simplified picture of the spectral “hilltops” pinpoints the frequencies and frequency modulations of features such as speech formants. This binary type of picture requires no grey scale and improves the resolution of small features. The “peak” display may be combined with other formats by means of a selector-combiner device. A novel analog integrator now provides flexible time-averaging by adding spectral cross sections in numbers variable from 2 to over 1000. The periods of averaging can be overlapped and the integrator could be equipped to provide simultaneous multiple outputs representing different averaging periods. The analyzer system is organized to take full advantage of the various kinds of flexibility with a minimum of operational steps. The combination of simple control, real-time operation, and strip-film recording provide the capabilities for large-scale investigations, while flexibility of analysis and display increase the information to be seen in the spectrographic pictures.
Axisymmetric Vibrations of Thin Elastic Shells
Authors: DeSilva C. N. , Tersteeg G. E.
Published: September 2005

The first part of this paper treats the axisymmetric transverse vibrations of membrane shells. The stress differential equations of motion with longitudinal inertia neglected are solved for a class of shells that includes the ogive, cone, cylinder, and sphere. The emphasis is placed on predicting the lowest natural frequency of vibration for shells with a free boundary. These frequencies are compared with the previously known results of the bending solutions for the shallow spherical-shell segment and for the hemispherical shell. In the second part, attention is turned to the shell whose mode of deformation is primarily flexural by applying hypotheses associated with edge effects. The deformation is specified by a pair of differential equations that are solved for a class of shells of revolution. The frequency equation is obtained and particularized to specific geometries.
Peak Factors in Subdivisions of the Speech-Frequency Band Weiant Wathen-Dunn
Authors: Lipke David W.
Published: September 2005

The relative powers and the corresponding peak factors in octave or half-octave divisions of the speech-frequency band take on renewed interest in the light of a recent report by Schneider [Frequenz 10, 97–106 and 152–161 (1956)] on the intelligibility of clipped speech where the speech is divided into sub-bands and clipped. Examination of the available power and peak-factor data leads to the conclusion that the latter has not been measured with an accuracy sufficient for the present purpose. Measurements of the peak factors in subdivisions of the speech-frequency band, using modern techniques, will be presented and related to previous power and peak-factor measurements.
Some Cues for the Distinction between Voiced and Voiceless Stops in Initial Position
Authors: Liberman A. M. , Delattre P. C. , Cooper F. S.
Published: September 2005

A series of experiments with synthetic speech indicated that each of the voiced stops could be made to sound like its voiceless counterpart by eliminating the beginning of the first-formant transition. The amount of first-formant “cutback” required to produce a voiceless stop varied according to the stop, the vowel which followed it, and the listener, but was in no case greater than 40 msec. It was also found that filling the first part of all formant transitions with noise (i.e., aspiration) contributed to the impression of voicelessness, but the importance of aspiration as a cue appeared to be considerably less than that of the first-formant cutback. Many listeners showed great consistency in differentially indentifying the patterns as voiced or voiceless even when the stimulus difference was seemingly very small. In one experiment, for example, several listeners sorted the patterns perfectly on the basis of a 10-msec difference in the starting time of the first formant. [This work was supported in part by the Carnegie Corporation of New York, and in part by the Department of Defense in connection with Contract DA 49-170-sc-2159.]
Identification of Turbulent Speech Sounds
Authors: Wiren Jacob
Published: September 2005

In the study of turbulent signals there seems to occur two classes, one which is stationary in nature and the other possessing transient characteristics. The former occurs in speech as fricatives (such as s) and the latter as stop sounds (such as t). It is often desirable to devise methods for separating them automatically. These will find their particular application directly in an electronic binary selection system for phoneme classification or indirectly for a speech analysis synthesis scheme using continuous parameters. Three methods have been considered for this task. They involve the use of (a) the duration of the sounds, (b) the total number of zero crossings of the wave form of the sound, and (c) the change of energy or spectrum during the onset of the sound with respect to a fixed time interval or a fixed number of zero crossings of the wave form. The relative merits of each method will be discussed, and a more detailed presentation will be made for the results of the third method. [The research in this paper has been made possible through support and sponsorship extended by the Electronics Research Directorate of the Air Force Cambridge Research Center, under Contracts AF19 (604)-1039, Item I, and AF19(604)-2198.]
Pitch Discrimination for Synthetic Vowels
Authors: Flanagan James L. , Saslow Michael G.
Published: September 2005

A psychoacoustic experiment to determine the just-discriminable changes in the fundamental frequency of synthetic vowels is described. The experimental variables investigated are: three synthetic vowels (/i, α, æ/), two sound pressure levels (60 and 80 db re 0.0002 dyne/cm2), and two fundamental frequencies (80 and 120 cps). A method of constant stimuli is employed in which subjects judge the pitch of the vowel as “higher” or “lower” in comparison to a fixed standard. The data indicate that the changes in fundamental frequency discriminated correctly 75% of the time are of the order of 0.3 to 0.5 cps. Application of the results to speech compression is suggested.
Stimulus-Oriented Approach to Detection
Authors: Jeffress Lloyd A.
Published: September 2005

Distribution curves for amplitude (envelope), drawn for noise and for noise plus signal, provide the basis for determining the proportion of area (probabilities) lying above various “criterion” levels. Probability pairs P (y|n) and P (y|sn) for various criterion levels furnish the coordinates of points generating ROC curves, which, because of the skewness of the distributions, show a slight curvature when plotted on normal-normal paper. This curvature (concave downward) provides a better fit to detection data obtained from rating-scale experiments than do the straight lines obtained from normal curves. The ROC curves belong to a family derived through the theory of signal detectability for the ideal observer in the case where signal phase is unspecified. The fact that the distribution for noise-plus-signal amplitudes has, in general, a larger variance than that for noise alone explains why many experiments find the ratio of σsn to σn to be greater than unity. A detection measure d, derived from the two distribution curves, when plotted against signal amplitude, is a straight line over most of its course but bends in to the origin for weak signals. Its failure to touch the positive abscissa supports the TSD argument against the threshold hypothesis. A second curve, derived from this one, provides a convenient way of determining the signal required to yield a particular value of ds, when the signal that yields some other value of ds is known. Finally, the concept of “effective bandwidth” is developed, and provides a single parameter for use in fitting detection data. Data give some support for the notion that the auditory system adjusts its bandwidth in accordance with the duration of the signal.
Calibration of Audiometers
Authors: Martens Alex E.
Published: September 2005

This paper considers the various techniques and equipment used in audiometer calibration. Sources of faulty performance in audiometers are pointed out and the methods of detection suggested. A complete laboratory calibration facility is described in some detail.
Some Useful Approximations for Determining the Vibration of Structures Excited by Random Pressures
Authors: White Pritchard H.
Published: September 2005

In computing the mean-square generalized force (or the joint acceptance) of a structure undergoing excitation by random pressures, approximations can often be made that will greatly reduce the computational effort and that do not affect the accuracy significantly. It is shown that the mean-square generalized force has an upper bound that is easy to compute, useful for irregular-mode shapes or correlation functions. In addition, it is shown that spatial variations in the mean-square pressure of an antisymmetric nature over the surface do not affect the joint acceptance, while the effect of symmetrical variations is small.
On the Discrimination Factor for a Continuous Distribution of Noise Sources
Authors: Arase Elizabeth M.
Published: September 2005

An exact expression for the discrimination factor (ratio of maximum-to-minimum power response) has been found for a vertical, equally spaced, linear steered array in an axially symmetric, peaked noise field. This quantity was evaluated for half-wavelength element spacing as a function of the number of elements, and for a 20-element linear array as a function of the interelement spacing. These calculations refine a previous approximate result obtained by Stone [J. Stone, J. Acoust. Soc. Am. 34, 328 (1962)].
Attenuation over RSR Paths in the Deep Sea
Authors: Urick R. J.
Published: September 2005

An analysis of signals received on a bottomed hydrophone from a series of explosive charges, dropped across the North Atlantic Ocean and described in a previous paper, indicates attenuation coefficients about 50% greater than those for transmission along the deep sound-channel axis. The attenuation is attributed to forward scattering by inhomogeneities in the body of the sea.
Effect of Pressure Reduction and Temperature Variation on the Performance of a Double Form of Helmholtz Resonator
Authors: Ingles A. R.
Published: September 2005

An account is given of the construction of a double form of Helmholtz resonator, which is compared with a resonator used by Tucker in earlier work. The variation of its resonance response and resonance frequency with pressure reduction have been investigated and the effects of pressure, temperature, and source-current variation on its damping at resonance are described. The neck corrections of the resonators have been calculated from their calibration constants and are compared with values derived from simple formulas.
Flexural Vibrations of Elliptical Plates When Transverse Shear and Rotary Inertia are Considered
Authors: Callahan W. R.
Published: September 2005

In this paper, the author solves the partial-differential equations governing the motion of plates, which were derived by Mindlin, Reissner, and Uflyand, by using product solutions and finds, by taking an infinite series of product solutions, that the boundary conditions are satisfied. The elimination of the arbitrary constants occurring in each boundary problem leads to the frequency equation for the normal modes of vibration. The frequency equation for each problem is an infinite determinant and each element in it is an infinite series of Mathieu functions containing as unknown the frequency. A method is described permitting one to find the roots of the infinite determinant. These roots represent the normal modes of vibration for the elliptical plate. Since the classical (Lagrange) theory of plate is good only for plate when the wavelength is large in comparison with the thickness of the plate, it is restricted to low-frequency vibrations. The present theory gives good results for high-frequency vibrations, essentially because it includes coupling between flexural and shear motions.
On Flow Fields Driving a Contiguous Acoustic Field
Authors: Powell Alan
Published: September 2005

The sound radiation from a slightly compressible flow can be calculated by estimating the pressure that would exist at an enclosing surface just as if the fluid were incompressible, this pressure then being inserted in the appropriate point-multipole expression for the sound radiation in a compressible fluid. The source strength is specified in terms of the vorticity, a simple result being given for the pressure in the incompressible flow; the final result for the farfield sound pressure is then the same as that of the theory of vortex sound.
Some Experiments on Sound Propagation in Damped Air Ducts with Flow Velocities up to 80 m/sec
Authors: Meyer Erwin , Mechel F. , Kurtze G.
Published: September 2005

In a rectangular duct with the cross section 35×100 mm2 one larger side is lined with sound absorbing devices. The used absorbers are rock wool (layer-thickness 6 cm) with and without perforated coverings, and undamped as well as damped resonators of the Helmholtz type. The flow velocities have been varied between 0 and 80 m/sec. The microphone used in the measurements has a probe tube with a front opening in the form of a slot around the tube in a distance of 5 tube diameters from the front end. The opening is covered by copper gauze. Measurements have been made with respect to sound attenuation and sound velocity as functions of frequency for different flow velocities, the signal to noise ratio being about 30 db. In general the sound attenuation in the duct decreases with increasing flow velocity. For absorbers without resonance character this is observed over a comparatively large frequency range. In the case of resonance absorbers the resonant frequency is shifted towards higher frequencies with increasing flow velocity. The attenuation decreases for the resonant frequency but above this frequency reaches higher values than without flow. Between these frequencies we have a range with largely decreased attenuation which latter even may reach negative values so that an amplification is observed.
Attenuation of Guided, Repeated Shock Waves in Gases
Authors: Medwin H.
Published: September 2005

The attenuation of guided, “plane,” progressive, repeated shock waves has been measured in circular tubes of radius ranging from 0.96–5.4 cm at several frequencies and intensities for air and five other gases. Analysis of the data leads to the conclusions: (a) the wall attenuation of a guided sawtooth wave corresponds to that of a single shock and shows no dependence on frequency; (b) correcting for wall loss by subtracting the experimental wall-attenuation term from the total attenuation does not eliminate the fundamental disagreement between the theoretical predictions for infinite sawtooth waves and the experimental values for guided sawtooth waves. The disagreement is apparently due to the gross discrepancy between the fluid-dynamic relations that are assumed by the theorists and the experimental situation. An empirical law is presented for the attenuation of guided, repeated shock waves in air.
Acoustic-Image Lateralization Judgments with Binaural Tones
Authors: Sayers B. McA.
Published: September 2005

Experiments on the lateralization of sound images, established by binaural single or multiple tones, are reported. It is argued that the concept of sound images having perceived position in an auditory space usefully describes relevant auditory experience and that the phenomena concerned can be conveniently parallelled by a correlation-type fusion model. The concept is used to clarify effects such as the occurrence of multiple images, discontinuities of lateralization judgments, and the interacting influence of interaural time delay and amplitude difference.
Effects of Speaking Condition on Pitch
Authors: Harris Cyril M. , Weiss Mark R.
Published: September 2005

Pitch changes that occur when a talker alters the speaking condition of his voice from “normal” to “loud” or to “soft,” for otherwise natural speaking conditions, were evaluated for two groups of recordings: (1) recordings of the same word, each spoken by a different talker having “general American” dialect, and (2) recordings of a group of different words spoken by the same talker—a trained phonetician. Using normal speech as a basis of comparison, the results of the first group of words for 14 talkers shows an average increase in pitch of 34% for loud speech and a decrease in pitch of 12% for soft speech. Similarly, the results for the one talker saying 28 words shows an average increase in pitch of 53% for loud speech and a decrease of 11% for soft speech. A third group of recordings of speech spoken in a monotone was analyzed to determine the standard deviation of the pitch fluctuations about the mean value of pitch for each word. For a group of 21 untrained talkers, the average fluctuation in pitch was 4.4%, in contrast with a value of 2.4% for a trained phonetician. Other results showed that an increase in speech-power level from normal to loud conditions resulted in an increase in the frequency of formant 1 of 11%, but no significant shift in formants 2 or 3 was observed.
Recording Ultrasonic Interferometer for Liquids
Authors: Hunter Joseph L. , Markowski Michael J. , Klopovic Joseph J. , Bruening Leonard F.
Published: September 2005

An interferometer has been constructed for the measurement of velocity and absorption in liquids. The design includes features for achieving and maintaining close parallelism between emitter face and reflector face over a large range of movement of the reflector. The reflector distance may be changed either manually or automatically. If driven automatically, the drive is taken from the gear box of a Bruel and Kjaer graphic level recorder through a flexible shaft and a reducing gear, so that the motion of the reflector is synchronized with the motion of the recorder paper. A precision gauge with a full range of six inches is firmly attached to the reflector shaft for a check on the travel of the reflector. If greater precision of distance measurements is required, provision is made for the insertion of gauge blocks. For extremely minute motions a differential drive may be inserted. The instrument is constructed in subassemblies, so as to be adaptable over a wide range of absorption coefficients. Convenience features include a self-contained temperature bath and accessibility of the crystal holder for ease of change of emitters.
Velocity of Sound in a Liquid Containing Gas Bubbles
Authors: Karplus H. B.
Published: September 2005

At low frequencies consideration of the quasi-static elastic moduli and densities of the gas and liquid parts of the mixture yields a value of sound velocity which is much lower than the velocity in either constituent. The computation has been confirmed experimentally in the concentration regions of 1 to 60% air by volume. The sound velocity was found from the change of phase in a plane progressive wave as a function of distance. Concentrations were determined from a measure of the hydrostatic pressure of the mixture. The “froth” was made by pumping the water rapidly past a porous glass filter through which the air was forced. A trace of detergent retarded the coalescence of bubbles. Minimum sound velocity in a water air mixture occurs at 50% concentration where the velocity is approximately 22 mps.
Loudness and Detectability Scaling of Bandpass-Filtered Short Tones
Authors: Creelman C. Douglas
Published: September 2005

Two observers adjusted gated sinusoids, passed through a bandpass filter and presented in a noise background, to equal the loudness of unfiltered signals. Bandpass-filtering decreased loudness relative to unfiltered signals when duration was less than about 100 msec. Detectability scales were constructed for 5-msec filtered and unfiltered signals presented in continuous noise, and the scales showed superior performance at the signal amplitudes used in the matching portion of the experiment for the unfiltered signals. The scale discrepancy was about 3 dB, whereas the loudness difference was about 5 dB. Some theoretical implications of the data are discussed.
Effects of Ultrasound on Aqueous Methyl Iodide
Authors: Steiner Edwin C. , Karpovich John
Published: September 2005

The irradiation of a heterogeneous system of methyl iodide and water with high-intensity ultrasound causes a free radical reaction to occur. The reaction was followed to its completion by measuring the volume of the gases liberated and the conductivity of the solution. The gaseous, liquid, and solid products were collected and identified. The gases liberated were principally methane along with lesser amounts of ethane, ethylene, propane, propylene, acetylene, butane, etc. The main liquid product was methylene iodide, whereas ethylene iodide was the main solid product. Hydrogen iodide and iodine were also formed. Methylene iodide, which has a low vapor pressure, was not decomposed by ultrasound. This observation supports the hypothesis that the aqueous methyl iodide reaction takes place in the vapor phase.
Further Observations on the Central Factor in Auditory Fatigue
Authors: Riach W. D. , Sheposh J.
Published: September 2005

A study was recently reported indicating a central factor in pure-tone auditory fatigue. A replication of that study yielded data that did not confirm the original findings.
The Effects of Ultrasound on Growing Bone
Authors: Vaughen Justine L. , Bender Leonard F.
Published: September 2005

The epiphyseal area of growing bone is currently considered a contra-indicated site for ultrasonic therapy. Previous studies indicate that damage occurs to bone cortex and bone marrow with high intensities of ultrasound. The effect of clinical doses of ultrasound upon the epiphyses of growing rabbits was studied. The left knee area of 20 animals was treated underwater with 1 w/cm2 from a 12 cm2 sound head for five minutes daily from the age of three months until there was x-ray evidence of epiphyseal closure (6 to 8 months). The untreated hind leg served as control. Comparison of the data showed no significant difference in bone length, microscopic appearance, or rate or manner of epiphyseal closure between the treated and control leg.
Comments on the Effect of Circumaural Earphones on Auditory Threshold
Authors: Tillman Tom W. , Gish Keith D.
Published: September 2005

It is shown that, for normal ears, the sound-pressure levels developed in a flat-plate coupler by the mean threshold voltages across the Sharpe HA-10 earphone and the Sharpe HF-15 earphone are highly equivalent from 125 through 8000 cps. For the same group of normals, the SPL's developed in an ASA type-1 coupler by the mean threshold voltages across a TDH-39-10Z earphone mounted in an MX 41/AR cushion agreed reasonably well with the data of Stein and Zerlin [L. Stein and S. Zerlin, J. Acoust. Soc. Am. 35, 1744 (1963)]. However, the threshold SPL's reported by these authors for the Sharpe HA-10 are approximately 20 dB higher than those from this experiment.
Variation of Sensitivity of Solid Dielectric Capacitance Transducers
Authors: Griffiths J. W. R. , Murarka N. P.
Published: September 2005

A capacitance transducer, using a thin metalized plastic film as a solid dielectric, can be subject to a loss of sensitivity owing to a reduction in the effective polarizing voltage caused by charge building up on the inner surface of the plastic. However, by a periodic reversal of the polarizing voltage, it is possible to prevent this accumulation of charge and, in consequence, the sensitivity of the device remains constant.
Relationship of Speaker Intelligibility to the Sound Pressure Level of Continuous Noise Environments of Various Spectra and Octave-Band Widths
Authors: Tolhurst Gilbert C.
Published: September 2005

The effects of six tilted and six octave-band ambient noise spectra upon speaker intelligibility were studied as each spectrum was presented at six different sound pressure levels through 125 db. Constant level recordings were made of 48 speakers talking in the noises, and these were subsequently played back to panels of listeners. The mean speaker intelligibility data were subjected to analyses testing speech score differences attributable to spectra and sound pressure level. The results indicate that, generally, as the ambient noise surrounding talkers is increased in sound pressure level there is a decrement in speaker intelligibility whether the noise is of a tilted or an octave-band spectrum. The differences were highly significant statistically. The −3 db per octave tilted spectrum yielded an average decrease in speaker scores of 2.3 percentage points per db increase of noise between 105–125 db of noise. The most detrimental octave-band noise, 1200–2400 cps, averaged 0.75 percentage points lower scores per db noise level increase. Statistically significant differences were found among each of the two general spectra types affecting speaker intelligibility. Greater differences were exhibited among the tilted spectra than among the octave-band noises.
Relationships among Threshold and Intelligibility Word Lists
Authors: Siegenthaler Bruce M. , Hardick Edward
Published: September 2005

Since development of the PB-50 word lists and their use for measuring discrimination loss, the PB-familiar (Hudgins), PB-kindergarden (Haskins), and the W-22 lists (Hirsh et al.) have been assembled. The relationship between P.A.L. test No. 9 and the PB-50 articulation curve has been described, as has the relationship between C.I.D. tests W-2 and W-22. Although the PB-F and PB-K lists are potentially useful in audiologic practice, their relationships to other PB lists and threshold tests have not been reported. Three series of observation were done: (a) Twenty-two normal hearing adults were given tests No. 9 and W-2, and articulation curves for PB-50, PB-F, PB-K, and W-22 lists. (b) Thirty-four children, ages eight to eighteen years, were given tests W-2 or the Picture Identification Test for threshold, and tests PB-50, PB-F, and PB-K at 40 db H.L. (c) Seventeen normal hearing and twelve hypacusic adults were given P.A.L. tests No. 9, and PB-F articulation curves to determine 50% intelligibility levels. The relative db levels for the threshold tests and various articulation curves are presented.
Perceptual Bases of Speaker Identity
Authors: Voiers William D.
Published: September 2005

This report describes all attempt to determine the number and nature of the basic ways in which voices are perceived to differ from each other by a typical listener. In the experiment, 32 listeners described their perceptions of 16 voices by means of a semantic-differential rating form. Analysis of variance was performed to determine the contributions of speakers, listeners, and various situational parameters to the variance of ratings on each item. Factor-analytic techniques were employed to determine the dimensionality of the speaker effect, the listener effect, and the effect of the interaction of speakers and listeners. Four factors, labeled clarity, roughness, magnitude, and animation were found to account for an average of 88% of the variance in mean ratings given speakers on each of the 49 items. Six dimensions were found to account for the common-factor variance in constant errors associated with listeners. Five dimensions were found to account for the common factor variance of the observed interaction of speakers and listeners.
Excitation of a Circular Cylindrical Cavity by a Circular Waveguide
Authors: Bjerke C. , Van Bladel J.
Published: September 2005

The problem of determining the pressure in a circular cylindrical cavity of radius b connected to a circular input waveguide of radius a is formulated in terms of an integral equation. Values of the reflection coefficient in the guide and of the pressure in the cavity are given in terms of the frequency and of the dimensionless ratio a/b. The problem of the cavity with an input and an output waveguide is also analyzed, and values of the transmission coefficient of this filter are obtained.
Covariance of Noise in Attenuating Media
Authors: Liggett W. S. , Jacobson M. J.
Published: September 2005

In this paper, the covariance function of noise at two points in a sound-carrying medium is derived for an arbitrary distribution of noise generators when the noise suffers attenuation and spreading loss. The analysis is then applied to the cases of a volume and a plane distribution of omnidirectional sources. It is shown that the effect of attenuation on covariance is generally negligible in the volume case but is ordinarily important in the plane case. For the plane distribution, an asymptotic expansion is derived that holds for small values of an attenuation parameter. This expansion is then used to study the effect of attenuation on covariance as a function of receiver separation, receiver-line orientation, and time delay.
Stimulator for Complex Acoustic Waveforms
Authors: Glaser Edmund M.
Published: September 2005

An audio-tone-burst stimulator has been designed that employs a Hall-effect multiplier. This instrument produces modulation of the audio tone(s) by the desired envelope signal. An envelope-waveform generator is used that can deliver to the modulator a choice of either a Gaussian pulse, a triangle, trapezoid, or trapezoidal pulse with Gaussian leading and trailing edges. The duration of each of these waveforms is adjustable from a fraction of a millisecond to about 50 msec. The envelope signal is amplified before entry to the multiplier by a dc power amplifier. The modulator can handle any audio signal (including noise), with spectrum extending as high as 40 kcps. The audio rejection between pulses is 60 dB. The unamplified output-power level is adequate to drive a pair of Beyer DT 48 earphones.
Behavior of Piezoceramic Projector Materials under Hydrostatic Pressure
Authors: Nishi R. Y. , Brown R. F.
Published: September 2005

Experimental work on the effect of hydrostatic pressure on the piezoelectric and high-field dielectric properties of two piezoceramic projector materials is presented. The two materials, a modified barium titanate and modified lead zirconate titanate, are characterized by low dielectric losses at high fields. In the pressure range 0 to 10 000 psi and at nonresonant driving fields up to 3 kV/cm, the variations observed in the permittivity and piezoelectric strain constants with hydrostatic pressure were less than 7%, and no significant variations were found in the dielectric loss. Aging studies at 10 000 psi showed that the permittivity and dielectric loss for both materials reached constant values after a few minutes. Possible mechanisms for the observed effects are discussed.
Strain Amplitude of Mc/sec Ultrasonic Waves in Solids
Authors: Alers G. A. , Fleury P. A.
Published: September 2005

The strain amplitudes of 10 Mc/sec sound waves in solids were measured under conditions in which standing waves were set up, as well as under pulsed conditions. The methods used were (1) measuring the equivalent electrical resistance of the transducer, (2) measuring the heating produced by absorbing the sound waves, (3) diffraction of light from standing acoustic waves, and (4) the changes in a nuclear magnetic-resonance-absorption signal produced by the sound waves. All these methods were in substantial (±20%) agreement with one another. Measurements with different characteristics for the coupling between the transducer and sample showed the importance of this thin film. The highest strain amplitudes were obtained at frequencies slightly higher than the quartz-transducer resonant frequency. Even higher strains could be obtained with coupling films approximately 14-wavelength thick.
Correlation Detection in a Duovelocity Medium, with Application to Seismic Disturbances
Authors: Cooper Paul W.
Published: September 2005

In a medium in which noise and signal propagate with different velocities, a detection scheme making use of the crosscorrelation between the received waveforms at two different locations offers a number of distinct advantages over one making use of ordinary autocorrelation of the received waveform. These advantages arise from the resultant relative shift between the noise and signal autocorrelation functions, allowing for separation of noise and signal when the noise characteristics or statistics are unknown, and even where the processes are nonstationary. Ramifications of the correlation shift are an improvement in signal-to noise ratio (even when noise characteristics are known), and capability for measurement of velocity, signal-source direction, and signal and noise and channel characteristics. With the current interest in detection of underground nuclear explosions, this paper is directed toward detection of seismic disturbances wherein effective use can be made of the multivelocity properties of the medium.
Doppler Shift of Sonar Backscatter from the Sea Surface
Authors: Mellen R. H.
Published: September 2005

Experimental measurements of the Doppler spectrum of sonar backscatter from the sea surface at 85 and 1400 kcps show no evidence of “resonance” predicted by first order linear theory. The Doppler spread and scattering strength are, however, in fair agreement with radar measurements in the same wavelength range.
Compression Wave Surrounding an Expanding Sphere
Authors: Naugolnykh K.
Published: September 2005

The method of describing the propagation of finite-amplitude waves based on the introduction of coordinates “accompanying” the wave system is used for the consideration of the radiation of a compression wave by a sphere that is expanding at a constant rate in a perfect medium. To estimate the degree of accuracy of this method, the results are compared with the exact solution of G. I. Taylor. [Proc. Roy. Soc. (London) A186, 273–292 (1946)].
International Audiometric Zero
Authors: Davis Hallowell , Kranz Fred
Published: September 2005

International reference-zero levels for pure-tone audiometers have been recommended by the International Organization of Standardization (ISO) and are under consideration for inclusion in a new American Standard for Audiometers. The new ISO levels are desirable because (1) the shape of the threshold contour is more accurate, (2) the threshold levels are reproducible from laboratory to laboratory and from country to country, and (3) they represent the only apparent escape from permanent ambiguity and confusion in the international exchange of audiometric information. The new ISO levels differ significantly from the American Standard values of 1951, but readings on one of these bases can readily be transferred to readings on the other base by a simple arithmetical adjustment. For instance, for the determination of percentage impairment of the ability to hear speech by calculation from the average of the decibel readings at 500, 1000, 2000 cps, an adjustment of 11 dB in the average of these readings provides the transfer from one base to the other.
Experimental Study of “Tone Deafness”
Authors: Tanner Wilson P. , Rivette C. Laurence
Published: September 2005

In a series of experiments designed to compare the efficiency of human observers in amplitude-discrimination tasks to their efficiency in frequency-discrimination tasks, the behavior of one of the four observers suggested that he was completely insensitive to frequency differences. The procedure of the experiments was then diverted to conduct an experimental case study comparing the “tone deaf” observer to three observers with normal frequency discrimination under a variety of experimental conditions. In amplitude-discrimination experiments in which he is detecting pulses of sine waves, he compares favorably. He far surpasses the other three observers when the signal is a sample of “white Gaussian” noise. An interesting aspect in the experiments reported is that the “tone deafness” of the participating observers suggests the possibility that these particular experiments may reflect culture-bound conditions. A further program is planned that may yield data on the question of the environmental influences on sensory capabilities.
Two Experiments concerning Rise Time and Loudness
Authors: Vigran Erik , Gjaevenes Kjell , Arnesen Gunnar
Published: September 2005

Some experiments are performed to test the influence of rise time on loudness of a 750-cps sinusoid and a broad-band noise. Rise times, defined for a 50-dB exponential variation in sound pressure level, were applied in the interval 0.025–1.6 sec. Maximum sound pressure level was 70–100 dB with duration 0.6 and 1.3 sec. A “paired comparison” method was used, and a decrease in loudness corresponding to approximately 3 dB in sound-pressure level was found for the broad-band noise. A smaller change was found for the 750-cps sinusoid.
Direct Mechanical Determination of the Dynamic Response of Diaphragms
Authors: Miles D. O.
Published: September 2005

The freefield resonant frequency and the deflection under given static pressure of a thin, circular, clamped-edge diaphragm may be calculated theoretically by well-known equations. Also, experimental means exist for a determination of these quantities. No satisfactory theoretical or experimental method has appeared, however, by which it is possible to obtain, for a complicated physical system, the diaphragm deflection as a function of the frequency of an applied sinusoidal pressure, over a frequency range that includes the natural diaphragm resonance. An experimental method is described by which a piezoelectric driver is employed to generate a sinusoidal pressure of variable frequency in a confined gas, to which one side of a test diaphragm may be exposed. Equations are derived describing the gas-coupling medium and the piezoelectric driver. By use of these equations, it is possible to predict the characteristics of the apparatus. A study is made of the dynamic response of a series of thin, circular, clamped-edge diaphragms. Since the diaphragm geometry is simple, the resonant frequency may be calculated theoretically. A shock-excitation technique is also employed to determine the resonant frequency. Comparison is then made between the latter two methods and the result given by the apparatus. The static-pressure dependence of the resonant amplitude and resonant frequency of the diaphragms is studied and discussed. The magnitude of the dynamic-pressure amplitude is determined, employing a calibrated commercial pressure gauge below its own resonance. Modifications of the apparatus are reported that extend the dynamic-pressure amplitude and the useful frequency range, and the possibility of utilizing the apparatus for dynamic calibration of pressure gauges is noted.
Distribution of Losses in Longitudinally Excited Vibrators
Authors: Benson R. W. , Chapman J. R.
Published: September 2005

A study of the loss distribution in longitudinally excited vibrators has been made for application to transducer design. The relative importance of losses related to longitudinal and shearing strains, the surface, and impedance transformations has been made. The experimental methods are described and analytical methods for the prediction of losses in various geometries are given. The losses at changes in cross section of a vibrator are found to behave in a predictable manner.
Turning-Point Peculiarities in the Near-Resonant Response of Slightly Tapered Membrane Strips
Authors: Goodier J. N. , Fuller F. B.
Published: September 2005

Unusual and surprising features of the response of a slightly tapered, nearly rectangular membrane, or analogous medium, excited at either the wider end or the narrower end and fixed on the other three sides are examined analytically. Radical differences between the two appear for the same “near-resonant” frequency. For excitation at the wider end, there can be a large-amplitude response in the wider half, while the narrower half remains almost undisturbed. For excitation at the narrower end, there is only small-amplitude response throughout. These peculiarities are associated with the presence of a “turning point,” in the sense of the WKB method used in the analysis.
Arctic Deep-Water Propagation Measurements
Authors: Buck Beaumont M. , Greene Charles R.
Published: September 2005

Experimental results of acoustic-propagation measurements made in the Beaufort Deep of the Arctic Ocean in April 1963 are given. Explosive source stations were made by light aircraft at distances of 3, 6, 9.5, 13.5, 26.5, 46, and 115 nm (nautical miles) from a manned camp where the signals from hydrophones in the water and seismometers mounted in the ice were recorded. From these measurements, and from ray calculations based on measurements of water temperature made during the experiment, the following were derived and are presented: transmission loss as a function of frequency, range, the relative energy content of signals from surface- and bottom-reflected rays; the relative effectiveness of hydrophones and ice-mounted vertical seismometers in detecting underwater sound energy; transmission loss in excess of predicted divergence loss.
Permanently Destaticized High-Fidelity Records
Authors: Brummet B. D. , Jaffe Sol S.
Published: September 2005

A technique is proposed for permanently destaticizing recording disks by the encapsulation of a continuously conductive inner liner that converts the electrostatic field about a point charge to a dipole field, thereby eliminating the problem of electrostatic dust attraction.
Recording the Waveforms of Periodic Acoustic Signals at Levels near and below 0.0002 μbar
Authors: Miller James D. , Engebretson A. Maynard , Weston Peter B.
Published: September 2005

A special-purpose computer is used for the on-line improvement of the signal-to-noise ratio at the output of a sound-level meter and for the recording of periodic acoustic signals of very low levels. This method is discussed in relation to the calibration of experimental audiometers.
Note on Binaural Masking-Level Differences as a Function of the Interaural Correlation of the Masking Noise
Authors: Durlach N. I.
Published: September 2005

A quantitative “black-box” model is constructed for interpreting data that describe the dependence of binaural masked thresholds on the proportion of common noise in the masking signals. This model is a natural adjunct to the equalization-and cancellation model, discussed in previous papers.
Harmonic Structure of the Tone of the Bassoon
Authors: Lehman Paul R.
Published: September 2005

The purpose of this investigation was to examine quantitatively and in greater detail than had previously been possible the harmonic structure of the steady-state tone of the bassoon. First, an attempt was made to determine the location of formants and the extent to which harmonic structure varies with sound-pressure level. Second, analyses were made of the tones of a group of professional bassoonists of recognized ability to determine the extent to which the harmonic structure of the tone varies from one player to another. Finally, analyses were made of the tones produced by the author to determine the extent to which harmonic structure varies from one sampling to another in the playing of a single individual. It was found that (1) there is a strong formant extending approximately from 440–500 cps and a weaker one from 1220–1280 cps; (2) the difference between the mean strengths of the fortissimo tones and the pianissimo tones of the professional bassoonists was only 10 dB; and (3) the variance in the strengths of the partials from sampling to sampling in the playing of a single individual tends to be approximately 75% as great as that from one player to another.
Reciprocity Calibration of a Standard Hydrophone at 16 000 psi
Authors: Sims Claude C. , Henriquez T. A.
Published: September 2005

A small, standard, lithium sulfate hydrophone has been calibrated by a reciprocity-coupler method in the frequency range 20 cps-3 kc/sec and at hydrostatic pressures from 0–16 000 psi. The sensitivity of the hydrophone is stable to within ±0.3 dB in this pressure range.