bluuebunny/crossref_metadata_2025 huggingface dataset:
Subjective Musical Pitch
Authors: Ward W. D.
Published: September 2005

The subjective relation “octave of” is demonstrated to be a valid interval for determining scales of musical pitch for pure tones presented successively. Octave judgments of trained musicians have a standard deviation averaging about 0.6 percent. Inter-observer variability is 2 to 5 times as great, increasing with frequency. Judgments vary significantly from day to day, but as the direction of shift at different frequencies for a single observer is random, the shifts cannot be attributed to changes in the octave criterion. Instead, this variability, and also (1) differences between right- and left-ear judgments of a given observer, (2) the change in difference between subjective and physical octaves as a function of frequency, and (3) the high inter-observer variability, all confirm the basic instability of pitch-frequency relations implied by the facts of binaural diplacusis.

Individual and group scales of musical pitch are deduced. In these scales, the average rate of change of musical pitch with respect to frequency level is less than unity by a small but significant amount. Although this discrepancy not explained, tests show that it is not an obvious artifact of method. Simultaneous presentation raises variability, but affects means only slightly. The relation betwen the peculiarities of individual scales and binaural diplacusis discussed.
Responding to Both of Two Overlapping Messages
Authors: Webster J. C. , Thompson P. O.
Published: September 2005

Air control tower operators listened to test transmissions, consisting of speech intelligibility tests couched in airplane-tower phraseology, over four channels. Part of the time the messages of two channels overlapped each other and the degree of overlap was systematically varied. The task was to respond to all messages.

The results showed a decrement in performance related directly to the amount of overlap, the leading message being understood better (unless it was considerably lower in intensity). For those parts of the message which had low informational content, the messages of the overlapping channel increased the total assimilated information per unit time above the total assimilated in the absence of the competing channel messages.
Determination of Equivalent-Circuit Constants of Piezoelectric Resonators of Moderately Low Q by Absolute-Admittance Measurements
Authors: Martin Gordon E.
Published: September 2005

The use of absolute-admittance measurements has been limited in the past to the determination of parameters of relatively high-Q resonators. By allowing only one major assumption in the analysis of the resonator, new equations are developed which consider the mechanical loss to be a first-order effect. On the basis of extensive numerical calculations of resonator characteristics in which no approximations were made, the errors of both the conventional relationships and the new equations are made evident. It is found that these new equations materially extend the usefulness of this method of measurement to include systems for which the mechanical Q is lower than the capacitance ratio. For the extreme case exemplified by a barium titanate ceramic resonator in air, the conventional calculation method introduces errors of approximately fifty percent in some of the crystal parameters as compared to errors of one percent for the new equations. The improvement is less significant in the determination of the parameters of underwater sound transducers.
Lamb's Problem with Internal Dissipation. I
Authors: Newlands Margery
Published: September 2005

A theoretical investigation is made of the response of an elastic half-space to a vertical impulse at the surface. Dissipative properties are incorporated in the medium and dissipation coefficients λ′, μ′ varying as the nth power of the frequency are assumed. These lead to dispersion and absorption. The response may be described by components of the three distinct types, P-, S-, and R-. Each is observed at the surface as a train of waves culminating in a characteristic phase about the instants r/α, r/β, and r/γ, respectively, where α, β, and γ are the velocities of propagation of P-, S-, and R- waves in nondissipative media and r is the focal range. These phases are discussed in detail; their “amplitude” and “span” are defined and the variations of each of these quantities and their ratios with r, density ρ and the material constants are derived. A schematic determination of λ and μ (the elastic constants), n, λ′, and μ′ from experimental data is outlined.
The Horn as a Coupling Element for Acoustic Impedance Measurements
Authors: Northwood T. D. , Pettigrew H. C.
Published: September 2005

Impedance tube methods of testing acoustical materials are restricted to frequencies below the value for which the wavelength is approximately equal to the largest lateral dimension of the tube. Above this frequency, extraneous modes of propagation interfere with measurements. The restriction is a serious one for typical acoustical materials that cannot adequately be sampled in less than 1 square foot. It has been found that the difficulty may be circumvented by using a horn to couple a large sample to a small impedance tube. Comparisons between horn and tube measurements have been made for a range of absorptive materials.
Analyzing Ultrasonic Pulses by the Split Reflector Method
Authors: McConnell R. A.
Published: September 2005

Frequency modulation within a carrier frequency pulse in the sonic microwave region is measured in this paper by comparing any span of several carrier cycles with every other such span along the length of the pulse. The method is especially suitable for modulation in the range of 0.1 to 5 percent.
On the Use of Ultrasound for Tumor Detection
Authors: Ballantine H. T. , Hueter T. F. , Bolt R. H.
Published: September 2005

Results are reported on recent investigations to test the possibility of detecting brain tumors by ultrasonic scanning. It is concluded that though compensated ultrasonograms (sound shadow pictures) may contain some information on brain structure, their are too sharply “noise” limited to be of unqualified clinical value.
Theory of the Effect of a Thin Air Film on the Vibrations of a Stretched Circular Membrane
Authors: Robey Donald H.
Published: September 2005

In the design of condenser microphones it is standard practice to insert holes or furrows into the electrode face. This modification helps to prevent radial air flow through the electrode-membrane interstice which can result in large dissipative and reactive effects, provided the separation is small.

The theory governing air reactions from an unmodified electrode is presented. An attempt was made to start with general fundamental equations. Only those simplifications which appeared to have a negligible effect on the accuracy of the results were made; for example, body forces and nonlinear terms have been neglected. Air inertia, rotational and irrotational velocity components, and viscous terms have been retained in the theory. Curves showing the effects of air reactions on the amplitude, phase, and impedance of a stretched titanium membrane are shown. The air stiffness, which continuously increased for increasing frequencies in the range 5 to 20 0000 cps, caused the amplitude of the membrane to diminish by more than 20 db. In general, air which is trapped behind the membrane will cause the response of the microphone to rise as the frequency is lowered.
Observation of the Tartini Pitch Produced by sin 11x+sin 15x and sin 11x+2 sin 15x
Authors: Meyer Max F.
Published: September 2005

The result of experiments with sinusoidal airwaves is that the ratio 11:15 makes the Tartini pitch 7 clearly audible, while neither a summation tone pitch nor a difference tone pitch nor any kind of aural harmonic is audible.
Some Factors Affecting Multi-Channel Listening
Authors: Egan James P. , Carterette Edward C. , Thwing Edward J.
Published: September 2005

Certain factors were investigated that affect the intelligibility of a speech message which is presented to a listener simultaneously with an interfering speech message. In two of the four experiments reported, filters were introduced into one of the two channels that carried the messages. Thresholds of perceptibility were not reliably decreased by moderate amounts of filtering of the received message. However, articulation scores were considerably increased by the use of a high-pass filter (500 cps) in either of the two channels.

The great advantage of presenting one message to one ear and the interfering message to the other ear (dichotic presentation) was measured by changes in the thresholds of perceptibility and by articulation tests. Functional relations between thresholds of perceptibility for the message to be received and the intensity of an interfering signal were determined for both monaural and dichotic listening. In separate tests, noise was also used as the interfering signal. Dichotic reception permits a reduction in intensity of the received signal of about 30 db as compared with monaural reception. Articulation-gain functions demonstrated a similar advantage for dichotic over monaural listening.

When the message to be received and the interfering message are monaurally received at equal intensities, the articulation scores for the designated messages are about 50 percent. If the message to be received is somewhat less intense than the interfering one, the cue value of the intensity difference offsets the increased masking of the less intense by the more intense message.
Correlation Functions for Noise Fields
Authors: Young James E.
Published: September 2005

The autocorrelation function for the noise pressure on the continuous space-time representation is discussed. It is shown that this function is determined throughout the space delay domain by the space correlation. This dependence can be formally interpreted on a causal basis where the delay τ is the “causal variable.” Specifically, the values of the space correlation and its time derivative at some instant τ = 0 all over space, serve to specify the autocorrelation for all later delays τ>0 throughout the infinite domain. In the closed domain, the boundary values of the space correlation and its normal derivative are also required to complete the description.
Compressional Waves along an Anisotropic Circular Cylinder Having Hexagonal Symmetry
Authors: Morse R. W.
Published: September 2005

Exact solutions are derived for the propagation of compressional elastic waves along an anisotropic circular cylinder having axial elastic symmetry (hexagonal elastic symmetry with the crystallographic axis coincident with the cylinder axis). Formal solutions are obtained for the displacement components, and a transcendental equation relating the phase velocity and the circumference-to-wavelength ratio is derived. The solutions are shown to reduce to the Pochhammer solution for the isotropic case. In the long wavelength extreme the velocity is dispersionless and is given in terms of the axial Young's modulus. In the short wave-length limit the velocity again becomes constant, similar to the Rayleigh surface wave limit in the isotropic case.
Acoustical Studies of the Tractrix Horn. I
Authors: Lambert Robert F.
Published: September 2005

When predicting and comparing the acoustical properties of horns it is customary practice to formulate the propagation as a one-parameter plane wave front problem. However, when particular attention is paid to the rapid flare near the mouth of a horn structure such as the tractrix, it also seems plausible to formulate the propagation on the basis of a one-parameter spherical wave front theory. By visualizing the surfaces of constant phase as spheres of constant radii a and the flow lines as tractrixes having a generating arm of length a, a one-parameter wave equation and Ricatti impedance equation may be derived. Solutions to these equations have been obtained by wave perturbation and by analog computer techniques.

Axial response and throat impedance measurements are compared with theoretical calculations postulating first a hemispherical and then a plane piston radiation pattern. It appears that the most satisfactory explanation lies somewhere in between these two limiting cases.
Effect of Arrival Time on Stereophonic Localization
Authors: Snow William B.
Published: September 2005

Exploratory tests under a variety of conditions were made during Bell Telephone Laboratories' studies on stereophonic reproduction to determine the effect of arrival time as a factor in localization. The recent rapid rise of interest in stereophony appears to warrant a summary of these old results (1934), for which the Laboratories has granted permission. It is shown that arrival time differences have essentially the same effect whether they are generated in the pickup room, listening room, or in the electrical system. They can therefore be made to add or compensate. Small differences (0-3 milliseconds) cause large shifts of localization angle, but the effect becomes relatively constant for larger differences. Time differences can be compensated by level differences. The results of two other experimenters are given for comparison. It is concluded that reasonable agreement is attained, considering the small total amount of data, but that more experiment is required to establish accurate quantitative relationships for practical stereophonic reproduction.
The Transient Tones of Wind Instruments
Authors: Richardson E. G.
Published: September 2005

Oscillograph records of the initiation of sound in organ pipes and orchestral wind instruments show large variations from one instrument to another. The causes of these variations and their artistic effects are discussed.
Perstimulatory Fatigue as Measured by Heterophonic Loudness Balances
Authors: Egan James P.
Published: September 2005

Perstimulatory fatigue is the decrease in loudness of a steady auditory stimulus during its presentation. In the past it has been measured by requiring a simultaneous dichotic loudness balance between two pure tones of the same frequency, one in each ear. Under these conditions the listener hears a single phantom sound whose localization depends upon the relative intensities of the two tones. The present investigation shows that the process of localizing the sound image in making the loudness balance is not critical to the occurrence of perstimulatory fatigue.

Two principal conditions were compared. In the first, the frequency of the comparison stimulus was the same as that of the fatiguing stimulus. In the second, the comparison and fatiguing stimuli differed sufficiently in frequency so that the listener always heard two pure tones which he could correctly localize in the two ears. It is concluded that the amount of perstimulatory fatigue is very nearly the same under these two conditions.

In the early phases of the present research it was suspected that the loudness balances were influenced by absolute judgments of loudness. A procedure is developed which precludes the formation of a single absolute standard of loudness. This method results in greater measured fatigue than the usual procedure.
On Latent Damage to the Ear
Authors: Harris J. Donald
Published: September 2005

The purpose of this communication is to serve as a warning to the now numerous people seeking to prevent partial deafness in ears subjected to loud noise. If the results in the figures herewith can be extended to the case of permanent threshold shifts, they may indicate that work periods should be set not only to allow the ear to recover to normal by audiometric test, but to provide in addition a time interval sufficient for the effects of latent damage to be dissipated.
Steady Rotational Flow of an Incompressible, Viscous Fluid Enclosed between Two Coaxial Cylinders
Authors: Skavlem S. , Tjötta S.
Published: September 2005

This paper gives a theoretical study of the two-dimensional flow of an incompressible, viscous fluid enclosed between two coaxial cylinders, one of which is oscillating. The Reynolds number is assumed to be small, and the Navier-Stokes differential equations are solved by means of the method of successive proximations. Both for the first and second order solution the proper boundary conditions are applied. We have shown that there exist two stationary circulation systems in every quadrant, and that the direction of circulation is opposite in these two systems. The circulation velocities are calculated in detail, and the results are compared with experimental results referred to in an earlier paper. Some new experimental results, which are not published yet, are briefly mentioned. The agreement between theoretical and experimental results is excellent.

In a discussion at the end of the paper we give the explanation of the remarkable fact that in some experiments the direction of circulation seems to reverse when the oscillation amplitude increases and exceeds a certain critical value.
Simple Derivation of the Boltzmann-Ehrenfest Adiabatic Principle
Authors: Greenspan Martin
Published: September 2005

The time-average forces exerted by the constraints of a vibrating system (radiation pressure, mean tension in a vibrating string, etc.) are easily computed from the adiabatic principle of Boltzmann and Ehrenfest (BE principle). The usual derivation from the “principle of varying action” is difficult.

Here an equivalent principle (which gives in addition the time dependence of the forces) is derived from Lagrange's equations. It is also shown how similar results can be got from the solution of a linear differential equation with slightly variable coefficients.
Sound Propagation into the Shadow Zone in a Temperature-Stratified Atmosphere above a Plane Boundary
Authors: Pridmore-Brown David C. , Ingard Uno
Published: September 2005

The sound field in the “shadow zone” (diffraction region) formed over a plane boundary in an atmosphere with a constant vertical temperature gradient is analyzed both theoretically and experimentally. The boundary condition at the plane is given by a normal acoustic impedance independent of the angle of incidence. As in the corresponding problem of underwater sound where the boundary is a pressure release surface, it is found that the major portion of the sound pressure in the shadow zone decays exponentially with distance at a rate proportional to the one-third power of frequency and two-thirds power of temperature gradient. The effect of boundary impedance enters mainly through its resistive component. The rate of sound decay for a pressure release boundary (zero impedance) is found to be 2.3 times that for a rigid boundary (infinite impedance).

Sound pressure measurements in the shadow zone in a laboratory chamber in which a large temperature gradient was created were made for both hard and absorbing boundaries, and the results were found in essential agreement with theory.
Aging of the Properties of Barium Titanate and Related Ferroelectric Ceramics
Authors: Mason W. P.
Published: September 2005

Barium titanate ceramics show an aging effect during which the dielectric constant and electromechanical coupling factor decrease while the elastic constants and Q increase. At room temperature, this process takes over a year to stabilize. By heating the ceramic up to 70°C the process is considerably shortened. A comparison of the rates of aging at 70°C and 25°C shows that an activation energy of about 19 kilocalories per mole is involved the aging process. The experiments and calculations made show that the cause of the aging is a reduction in the effective polarization caused by a slow temperature-induced motion of the domain walls of the ceramic. This motion is biased by the residual strains stored up when the crystal becomes ferroelectric and also by strains induced by the poling process. It appears likely that the high activation energy measured arises from the simultaneous motion of a number of unit cells in a bordered wall. Due to this high activation energy, aging can be speeded up by a heat treatment process.
A Tentative Method for the Measurement of Sound Transmission Losses in Unfinished Buildings
Authors: Raes A. C.
Published: September 2005

The method described in this paper attempts to measure the transmission loss of any wall independently of the surrounding elements of the building. The extreme case of a wall without any surrounding elements, i.e., the first wall in a building under construction, is included in the problem.
Interference Patterns in Reverberant Sound Fields
Authors: Waterhouse Richard V.
Published: September 2005

In a reverberant sound field, where at all points equal mean energy flows in all directions, it is shown that the sound energy is distributed into interference patterns the reflecting boundaries. Thus the mean energy density is not uniform at all points in the field. For a perfectly reflecting plane surface that is large compared with the wavelength, the interference pattern can be expressed as a mean squared sound pressure varying as (1 + sin2kx/2kx) where x is the distance from the surface and k is the wave number. Corresponding expressions are derived for the mean squared particle velocity and the mean energy density. The energy level at the surface is found to be 2.2 db higher than at points further away where the interference patterns are negligible. Similar expressions are derived for the interference patterns formed by two and three reflectors at right angles, as at the edges and corners of a room. The largest departure from uniformity occurs in a corner where the mean squared pressure is 9 db higher than at remote points. The effects of such interference patterns on transmission loss and reverberation room measurements are discussed briefly. The patterns are not much affected by the frequency band widths habitually used in room acoustics. Experimental confirmation of the theory is given.
Transducer Design for Ultrasonic Delay Lines
Authors: McSkimin H. J.
Published: September 2005

The problem of obtaining low loss ultrasonic delay lines for switching, computer, and certain radar applications is discussed. An analysis is made of structures using half-wavelength and quarter-wavelength bonds between the transducer and the acoustic medium to widen the pass-band; results are listed for both quartz crystal and barium titanate transducers.

For barium titanate transducers (80 percent BaTiO3, 12 percent PbTiO3, 8 percent CaTiO3), it is shown that a theoretical flat band width of approximately 30 percent with less than 1 db midband loss can be obtained with a bond of negligible thickness. This band width can be increased to approximately 46 percent without additional loss if a properly designed bond is used, (i.e., 14λ bond for radiating into water, 12λ for use with a fused silica delay medium). A 70 percent band width can be obtained with only 4 db loss per transducer.

Confirming experimental results are described for delay lines using quartz crystals and one-half wavelength plastic seals or one-quarter wavelength solder seals. For the latter, band widths of 85 percent of midband frequency have been obtained. An efficient delay line using BaTiO3 transducers is also described.
Theory of Noise and Vibration Insulation of a System with Many Resonances
Authors: Skudrzyk Eugen
Published: September 2005

The results obtained in a previous paper, Part I of this study, are summarized and used to derive the theory of vibration and sound insulation of systems with many natural frequencies, such as machines with more than one resonance mounted on resonating springs, a motor spring-mounted on a shell, or plates at higher frequencies. At lower frequencies, the quality of the insulation is a function of the ratio of the square of the lowest fully excited resonant frequency to that of the frequency of the force. Weakly excited natural modes cause spikes in the transmission curve. Resonances in the vibrating masses may annihilate completely the effect of the vibrator mounting, whereas resonances in the springs are harmless as long as the mass is small in comparison to that of the machinery. Spring mounting a vibrator on a shell or plate reduces the noise level considerably. Any measure that increases the fundamental natural frequency to the housing helps to improve vibration insulation. Mounting the vibrator in a rigid cage or onto a rigid girder seems to be expedient; and welding these along a whole circumference or along their whole length onto the housing, to simulate a one-dimensional vibration pattern, is expedient.

The noise radiation of a shell or plate to greater distances can be reduced by increasing the mass of the radiating shell or plate and by decreasing its size sufficiently to reduce the number of modes that radiate sound. Damping diminishes the sound radiation at lower frequencies, but has very little effect on it at higher frequencies.
On Some Poststimulatory Effects at the Threshold of Audibility
Authors: Zwislocki J. , Pirodda E. , Rubin H.
Published: September 2005

Poststimulatory threshold shift has been measured for 1000-cps stimuli of varying duration and sensation level, turned on and off either without audible transients or abruptly. The measurement was performed by means of test stimuli of varying duration and following the prime stimulus at various time intervals. The results show that the poststimulatory threshold shift depends little on the duration of the test stimulus, but that it depends critically on the time interval between the termination of the prime stimulus and of the test stimulus. The poststimulatory threshold decreases as this time increases. The poststimulatory threshold increases with sensation level and it depends in a complex fashion on the duration of the prime stimulus. The time pattern of the threshold changes radically when a gradual cutoff of the prime stimulus is replaced by an abrupt one. Replacing the 1000-cps tone by a random noise leads to the same result as an abrupt cutoff.
Comparison between the Performances of a Time-Averaged Product Array and an Intraclass Correlator
Authors: Fakley D. C.
Published: September 2005

Berman and Clay [J. Acoust. Soc. Am. 29, 7 (1957)] have investigated the directional characteristics of a linear array of omnidirectional receiving elements when the output from these elements are multiplied together and time arranged in certain ways. They conclude that the same directional characteristics may be obtained from these “time-averaged product” (TAP) arrays having a small number of detectors as with an additive array with a large number of elements; they also show that there is some economy in terms of the over-all length of the array required to give a specified beam width. Because it is not possible to assess the characteristics of a TAP array solely on the basis of its polar diagram, it is necessary to carry out a detailed analysis to determine its usefulness in applications which require a system with a narrow polar diagram. Three particular applications are investigated, namely the detection of a point source against a noise background, the resolution of the signals from two closely spaced point sources, and the exploration of the distribution of power across an extended source. For comparison purposes a parallel analysis is carried out for an intraclass correlation system. For simplicity, the analyses are confined to investigating the performance of a 4-element linear array with equal spacings between adjacent elements under elementary and idealized conditions. The results so obtained, however, are of general application. Two class I TAP array systems are compared with the intraclass correlator, the detection performance of which was analysed by Faran and Hills [Acoustics Research Laboratory, Harvard University, Techn. Memo. No. 28 (November 1952).] and which is believed to be the most “efficient” detector in this application. {A class I array is defined as one in which the number of time averaging operations lies between (N − 1) and 12N(N − 1), where N is the number of receiving elements. A class II TAP array, which employs true multipliers, is obviously inferior to a class I array in terms of detection performance and will not be considered. It has been shown by Melton et al. [see B. S. Melton and P. R. Kerr, Geophysics 22, 553 (1957), for example] that a class II type of array employing coincidence detectors rather than multipliers has some useful properties but it can be demonstrated that its detection performance is inferior to that of an intraclass correlator. Since class III TAP arrays have the same detection performance as the system prior to the power and sum circuits there is no need to analyse such arrays here.}
Pressure Phone for Hydrophone Calibrations
Authors: Sims Claude C. , Bobber Robert J.
Published: September 2005

A small, closed system for the absolute calibration of a standard hydrophone is described. The method allows control of the static pressure and temperature and is applicable at frequencies up to 5 kc. The system is designed so that the blocked or Thevenin pressure of the sound source is the same as the sound pressure acting on the hydrophone. The use of a hydrophone, calibrated with a pressure phone, as a standard in large closed-chamber systems is discussed.
Multiple Observers, Message Reception, and Rating Scales
Authors: Decker Louis R. , Pollack Irwin
Published: September 2005

The improvement of message reception in noise with multiple observers was analyzed. Two sets of decision rules were employed to select among the responses of three observers as follows: one based upon the response agreement among observers; one based upon the listeners' confidence ratings of accuracy of message reception. Confidence ratings substantially improved the selection of the correct message reception in the absence of response agreement among observers.
Modifications to Standard Pulse Techniques for Ultrasonic Velocity Measurements
Authors: Myers A. , Mackinnon L. , Hoare F. E.
Published: September 2005

A description is given of modifications to the “sing-around” and coincidence techniques for velocity measurement. In the case of the “sing-around” method a gate is incorporated which effectively lengthens the ultrasonic path by allowing retriggering on multiply reflected pulses. This allows the use of short solid specimens having low attenuation. The coincidence technique is modified by using an unrectified rf display and an electronic counter-timer to measure the pulse recurrence frequency. In both methods, an accuracy of 1 in 104 can be achieved in measuring the transit time for 10-Mc/sec waves through a low-absorbing specimen before correction is made for the effect of transducer-specimen bonds, etc.
Description of the Resonances of Short Solid Barium Titanate Cylinders
Authors: Arnold J. S. , Martner J. G.
Published: September 2005

The distributions of axial and radial vibration on the plane surfaces of short solid cylinders (disks) of barium titanate were experimentally determined for a number of modes. A vibration mode chart was prepared, to relate the types and frequencies of the prominent modes to the cylinder size and geometry. The electrical and mechanical aspects of the disk vibration indicate that there is no simple relationship between the electrical and mechanical measurements that are indicative of vibration amplitudes in different modes. A tentative explanation of this phenomenon is suggested by the experimentally disclosed existence of circulating currents in the disk electrodes.
Acoustical Resonances Produced by Combustion of a Fuel-Air Mixture in a Rectangular Duct
Authors: Elias Isidor
Published: September 2005

An experimental program was conducted with a 212 × 10 in. model ramjet combustor directed towards understanding the mechanisms which maintain high-frequency combustion pressure oscillations (commonly referred to as “screech”) in the air-breathing jet engine. Results show that pressure oscillations characteristic of transverse acoustic modes occur as fuel-air mixtures approach stoichiometric values. The particular mode excited is related to orientation of the flame fronts in the duct, which in turn are functions of the particular flame holder geometry. It is shown that heat release associated with the flame fronts occurs in high-impedance zones for the modes excited. High-speed motion pictures of the combustion zone during screech show that the flame fronts are serrated, the number of serrations being proportional to screech frequency. The serrations are interpreted to be related to vortex shedding from the flame holder lips. High-amplitude oscillations corresponding to the fundamental longitudinal mode occurred when conditions of intense screech were achieved. This mode transference is attributed to increased heat addition in the forward portion of the duct, a position favorable for driving longitudinal modes. Preliminary results show that high-turbulence levels produce screech at lower values of fuel-air mixture.
On the Conceptual Necessity and Use of Perfect Couplers in Schematic Diagrams
Authors: Trent Horace M.
Published: September 2005

If the criterion is adopted that a schematic diagram of a system must give a complete representation of all the physical or engineering principles involved including a specification of the characteristics of each part and how the various parts are joined to form the system, it follows that perfect couplers must be included the list of items available to anyone creating schematic diagrams. It is shown by examples that perfect couplers produce their action by the imposition of constraints and that the set of constraints for a given coupler imposes the condition of no power loss or gain. Conversely, if a conceptual device is known to be a perfect coupler and some constraints are known, then the remaining ones can be deduced. It is shown that perfect couplers may be of two types and that examples of each type are common. It is further pointed out that perfect couplers present no problem if an investigator is always aware of their possible existence. The discussion closes by showing that couplers can be dealt with mathematically in a systematic manner.
Analysis of a Logarithmic Solion Acoustic Pressure Detector
Authors: Wittenborn A. F.
Published: September 2005

An analysis is given of a solion acoustic pressure detector which has a direct current output proportional to the logarithm of the pressure input. An approximate method is used which avoids solving the Navier-Stokes equation describing the fluid flow and the convection diffusion equation for calculating the current.

The calculation consists of (1) solving the zero flow “transient” diffusion equation for the reducible component in the electrochemical redox system, (2) using this transient solution to calculate the output current, with the time spent inside the detector orifice as the independent variable, and (3) relating this time to the pressure by using the known acoustic impedance of the detector orifice.

The calculated results show that the logarithmic response is obtained through a combination of diffusion and hydrodynamic effects. For the ideal case of constant impedance as a function of volume flow, the logarithmic response is degraded.
Three-Dimensional Investigation of the Propagation of Waves in Hollow Circular Cylinders. II. Numerical Results
Authors: Gazis Denos C.
Published: September 2005

The results are given of a numerical evaluation of a characteristic equation derived in Part I, appropriate to free harmonic waves propagated along a hollow cylinder of infinite extent. This equation is evaluated for some representative cylinders covering the entire range from thin shells to solid cylinders, and the results are compared with the corresponding results of a shell theory. Observations are made regarding the variation of the frequency spectrum with the physical parameters, as well as the range of applicability of shell theories.
Some Characteristics of Long-Range Explosive Sound Propagation
Authors: Arase T.
Published: September 2005

A brief discussion given, in terms of ray theory, of the character of explosive sound which has propagated for long distances in the ocean. In addition to the arrivals previously studied, a “leakage” arrival has been observed. This arrival has been analyzed for travel time and spectrum level. The attenuation rate has been plotted as a function of frequency. The similarity of this attenuation rate to the theoretical and experimental attenuation rates for the surface channel indicates that the leakage arrival is due to energy that in part travels in the surface channel and in part is refracted.
Relation between Recovery from Temporary Threshold Shift and Duration of Exposure
Authors: Ward W. Dixon , Glorig Aram , Sklar Diane L.
Published: September 2005

Approximately 20 db of TTS at 3 and 4 kc, measured 2 min after cessation of the TTS-producing stimulation, was produced in 14 normal listeners by three different exposures to 1200- to 2400-cps noise: to 106 db SPL for 12 min, to 98 db for 27 min, and to 90 db for 117 min. Despite the fact that the TTS produced at other frequencies was different for the three exposures, the courses of recovery at 3 and 4 kc were indistinguishable. From these results and those of others, it is concluded that the course of recovery from TTS is uniquely determined by the value of TTS at 2 min recovery: i.e., by the TTS remaining after the first fast recovery process, the so-called R-1 recovery process, has run its course.
Beats in Cochlear Models
Authors: Tonndorf Juergen
Published: September 2005

Beats in cochlear models were studied from two aspects.

(1) Their effect upon cochlear fluid motion which, occurring along elliptical orbits, essentially represents Lissajous figures. The orbits expanded and contracted synchronously with the beat rate. Thereby, a partial rectification (asymmetrical expansion) became apparent which, occurring opposite directions in the two scalae across the partition, constituted the beat. This latter phenomenon was caused by the stiffness gradient of the cochlear partition.

(2) Their effect upon the traveling wave pattern along the partition was originally described by Békésy. Stroboscopic examination revealed that the beat frequency modulates the two primaries thus producing two additional side bands. However, the displacement pattern of the membrane when viewed by high-speed motion photography did not give any evidence of these five frequencies. Only the intertone (and the beat) was present. It then became apparent that the model is really a pattern analyzer of complex sound. In terms of cochlear fluid motion, it is able to resolve complex Lissajous by a spatial filter action along the partition into simple Lissajous. Any deviation from steady Lissajous, which ordinarily result from primaries in relation of integral numbers, produces beats. Thus beats of imperfect unison as well as of mistuned consonances have essentially the same cause: a cyclic phase change between the two primaries.
Ultrasonic Absorption Microscope
Authors: Dunn Floyd , Fry William J.
Published: September 2005

This paper constitutes a progress report on the development of an ultrasonic instrument for detecting microstructure. The principle of operation of the device (designated by the term “ultrasonic microscope”) is as follows: The specimen is imbedded in a liquid, which closely matches it in acoustic impedance, and is irradiated with short pulses of high-frequency sound. Some of the ultrasonic energy is absorbed in the specimen and the remainder leaves it and excites a small thermoelectric probe placed immediately adjacent to the region being investigated. As the specimen, which is between the sound source and the probe, is moved in a direction normal to the direction of sound propagation, a varying acoustic signal will be detected by the probe. This is a consequence of the fact that the amount of acoustic energy absorbed by the specimen in the portion immediately adjacent to the probe is determined by the structure of that part of the specimen.

Preliminary experimental results obtained with such a “microscope” operating at a frequency of 12 mc/sec are presented.
Ultrasonic Spectroscopy in Liquids
Authors: Litovitz T. A.
Published: September 2005

The molecular basis for ultrasonic absorption in liquids is reviewed. The various loss mechanisms are all relaxation processes which include such phenomena as vibrational, isomeric, structural and shear relaxation effects. The relation between such factors as the relaxation time and the properties of the liquid are considered.
Binaural Interaction of High-Frequency Complex Stimuli
Authors: David E. E. , Guttman Newman , van Bergeijk W. A.
Published: September 2005

An experiment is described in which time and intensity differences of 2-kc high-pass clicks were mutually offset to produce sound images centered in the head. Binaurally correlated and uncorrelated clicks were used, and the trade was tested at 10–70 db SL. The results show that generally the two types of clicks behave similarly, and that up to 60 db SL, at least, as over-all intensity increases, the time difference compensating a given intensity difference (in db) decreases. A function is derived describing what is interpreted as a physiological intensity-to-time conversion. The place of such a conversion in lateralization is discussed.
Sound Recording and “Publication” of Acoustical Research
Authors: George W. H.
Published: September 2005

Sound recording and reproduction has reached a sufficiently advance stage to justify its use as an aid to research publication in acoustics. Examples are quoted and the advantages discussed. A plea is made for its systematic use and a practical plan is proposed, based on the use of national archives already established in Washington, London, Paris, Rome, and Vienna.
Sound Transmission through a Velocity Discontinuity
Authors: Gottlier Peter
Published: September 2005

The attenuation of a sound wave in a steady flow, with the flow gradient normal to the flow lines, is approximated by three different methods. The first method approximates the steady flow by layers of constant velocity and applies the boundary conditions of Ribner at each interface. The second method uses the analytic solution for the continuous flow. The last method is similar to the first but uses the boundary conditions of earlier authors. It is found that the first and second methods give the same answer, and this answer disagrees with that obtained by the third method.
First Presbyterian Church, Stamford, Connecticut
Authors: Klepper David L.
Published: September 2005

This church is unusual in that the basic architectural shape provides the desired acoustical environment, requiring no “applied” sound-absorbing material. Hearing conditions are highly satisfactory for both speech and music. The reverberation time characteristic discussed along with the “gain” provided by the pulpit canopy.
Acoustics of the Fredric R. Mann Concert Hall, Tel Aviv, Israel
Authors: Beranek Leo L.
Published: September 2005

The Fredric R. Mann concert auditorium for an audience of about 2900 and a volume of 750 000 cu ft opened on October 2, 1957. This article covers general design objectives, factors influencing reverberation time (the final value of reverberation time at 500–1000 cps with full occupancy is 1.55 sec), shaping, means for controlling reverberation, echo studies, orchestra enclosure, control of exterior noise, and subjective assessments and recommendations for subsequent changes.

The auditorium was designed in accordance with specifications laid down by the Building Committee in September 1951. The design achieved the original objectives. Some changes in the orchestra enclosure and ceiling are desired by the musicians. Acceptance of the hall by audiences has been excellent.
Reverberation Formula Which Seems to Be More Accurate with Nonuniform Distribution of Absorption
Authors: Fitzroy Dariel
Published: September 2005

Reverberation measurements, made in rooms where the absorption is nonuniformly distributed, usually vary widely from predictions based on the currently employed formulas. Through extensive tests made in a large number of rooms, where distribution of sound absorption varies widely in uniformity, an empirically derived equation is submitted. Photographs of graphic recorder decay curves, showing contrasts in predicted slopes, seem to confirm the validity of the formula. The recorder curves are from field tests. The data submitted are a small portion of an accumulation of measurements, covering several years, in rooms of widely varying volumes, widely varying boundary ratios, and marked dissimilarity in amounts of absorption and ratios of absorption distribution.
On the Validity of the Loudness Scale
Authors: Stevens S. S.
Published: September 2005

Although encouraging progress has been made in the measurement of loudness, certain objections to the sone scale have been raised from time to time. This paper tries to answer some of these objections, and especially to show how the form of the sone scale can be verified by cross-modality matchings. Instead of working with numerical estimations of magnitudes or ratios, these new procedures allow observers to equate the apparent intensity of stimuli in two different sense modalities. It turns out that the results of these cross-modality matches can be predicted from the relation between the sone scale and the subjective scales in the other modalities. These experiments strengthen the evidence for the validity of the sone scale. They also suggest that the form of the subjective intensity function depends on the “input-output” operating characteristic of the sensory system and not on some prior experience which the observer may have had with a “physical correlate” of the stimulus.
Speed of Sound in Distilled Water as a Function of Temperature and Pressure
Authors: Wilson Wayne D.
Published: September 2005

An ultrasonic pulse type apparatus was used to measure the speed of sound in distilled water over the pressure range 14.7 to 14 000 psia and the temperature range 0.9 to 91.2°C. The temperature where the maximum sound speed occurs shifts to a higher temperature when the pressure is increased. At atmospheric pressure the computed maximum speed was 1555.36 m/sec and occurred at a temperature of 74.164°C. The isotherms of sound speed, plotted as a function of pressure, are concave upward below 20°C, concave downward above 20°C, and are approximately linear near 20°C for the pressure range of 14.7 to 14 000 psia. These curvatures have a maximum value of 1 part in 300 compared to the estimated accuracy of measurement which is 1 part in 10 000. The results are presented in tables and also in the form of a fourth degree equation fitted to the experimental data by the method of least squares.
Dynamic Force Measuring System for Machinery Vibration with Particular Application to Balancing of Assembled Machines
Authors: Barraclough T. W. , Collier R. D. , Summers A. C.
Published: September 2005

The dynamic force measuring system for the measurement of machinery vibration is based on the use of four piezoelectric force transducers. These transducers are installed between the feet of the machine under test and a terminating foundation, preferably a large seismic mass. The four signals are combined in two ways: (1) as a phasor sum to provide a single vertical force measurement and (2) as a sum and difference with equivalent moment arms to provide torque measurements. These fundamental measurements are based on force and torque equations developed from the six motions of an assumed rigid body. At the fundamental frequency of machinery vibration the two combined signals provide a measure of static and dynamic unbalance. The force spectrum may be analyzed by conventional means to provide frequency and amplitude information.