bluuebunny/crossref_metadata_2025_split huggingface dataset:
Channels of Reception in Pitch Discrimination
Authors: Pikler Andrew G. , Harris J. Donald 
Published: September 2005

Pitch discrimination was studied in 4 normal hearing subjects monaurally, binaurally, and in a variety of other channels of reception. No difference exists in sensitivity between the two normal earn of a subject, nor is there a difference between the sensitivity of the monaural channels and the binaural channel if all are matched for loudness. Also bone conduction was found to yield essentially equal pitch DL's after loudness was matched. All channels, except successive interaural, are equivalent under matched conditions. Successive interaural channels (standard in the right, variable in the left, and vice versa) show some deterioration of sensitivity and some increase in variance which can be attributed to the monetary fluctuations of diplacusis. Similar fluctuations were found also with respect to a channel utilizing a monaural standard and a binaural variable stimulus, the two ears matched in loudness. Under these conditions, furthermore, a third pitch is sensed, a phenomenon we term “triplacusis.” The authors suggest an interpretation of diplacusis and triplacusis as interaural interactions.
In cases of perceptive hearing loss, however, the channels are not usually equivalent in pitch discrimination even if matched for loudness. Evidently other principles must be sought for the pathological case.
An Instantaneous Pitch-Period Indicator
Authors: Dolanský Ladislav O. 
Published: September 2005

Instantaneous indication of the beginnings of individual pitch periods of a voice-sound speech wave is often desirable in speech analysis. With conventional means, such as linear filtering and subsequent waveform shaping, this instantaneous indication is very hard to achieve because of the considerable time delay involved.
In the “instantaneous” pitch-period indicator the problem is solved by using nonlinear techniques and a variable time-gating circuit; a pitch-period beginning is indicated by a marker pulse having a maximum delay of the order of five percent of the pitch-period duration. The application of the device to certain problems of speech analysis is indicated.
The Application of Correlation Techniques to Some Acoustic Measurements
Authors: Goff Kenneth W. 
Published: September 2005

This paper discusses the application of an analog correlator which computes the crosscorrelation function between two sound pressures to such measurement problems as the localization of noise sources, the determination of transmission loss, and the reduction of microphone wind noise.
The crosscorrelation function φ21 (r) between two nonperiodic signals will have a peak in amplitude if a component of each signal originates from a common source. The value of time delay τ for which this peak occurs equals the difference in time required for the individual components to propagate from the common source to the two points under study. An analog electronic correlator described in a companion paper has been constructed which, by employing this property of the crosscorrelation function, can separate the acoustic signal at a given point into components according to: (1) their points of origin (assuming independent sources), (2) the transit time from source to the point in question, and (3) frequency.
Preliminary experimental results show that correlation provides a practical method for determining the amount of sound contributed to the field at a given point by each of several sources. The correlator, by separating the signal transmitted directly through the structure from the flanking signal on the basis of arrival time, is also a useful tool for measuring the transmission loss of walls.
Auditory Perception of Submerged Objects by Porpoises
Authors: Kellogg W. N. 
Published: September 2005

Two captive porpoises (or bottle-nosed dolphins) were given a variety of tests for their ability to perceive and avoid objects in water by reflected sound signals. The tests were made in a specially constructed anechoic pool in which visual perception was eliminated by the turbidity of the water. The results showed that trains of underwater sound pulses were emitted periodically by the animals in this situation whether they were swimming or at rest. The signals became more numerous when reflecting targets were lowered into the water. Sound pulses could also be triggered by surface splashes, but they were not sustained after a splash if no target was present. These porpoise sonar noises are similar in some ways to man-made sonar, although they differ from it in several important characteristics.
The porpoises would locate and approach food fish by this method but would avoid nonedible objects. They were also able to swim accurately through a field of obstructions without colliding with them—even in darkness. The ability to avoid obstacles by sound did not appear to be affected by artificial jamming noises.
American Standard Recommended Practice for Laboratory Measurement of Air-Borne Sound Transmission Loss of Building Floors and Walls
Authors: Ingard K. U. , Huntley R. , Jack W. A. , Summerfield M. B. , Tyzzer F. , Waterhouse R. V. 
Published: September 2005

The American Standards Association recently issued the standard which is reproduced below, complete and unabridged, with their permission.
This new standard can be regarded as an up-to-date revision of the ASTM Tentative Recommended Practice for the same measurement (ASTM E 90-50T, later ASTM E 90-55), which was printed in this Journal [23, 686, (1951)]; in 1955 the “Tentative” was deleted from the title, the text remaining unchanged.
Some other countries, including Britain and Germany, have standards on this topic (British Standard 2750:1956, and German Standard DIN 52210, both obtainable from the American Standards Association), and a draft exists for an international standard; the latter includes provisions for field measurements as well as laboratory measurements, and for measurements of impact as well as air-borne sounds. At present ASTM Committee E-6 is working to prepare a new Recommended Practice for the measurement of the sound transmission loss of building structures, and will consider the inclusion of field and impact measurements.
Vowel Overlap as a Function of Fundamental Frequency and Dialect
Authors: Brubaker Robert S. , Altshuler Morton W. 
Published: September 2005

Two groups of young adult male college students spoke the syllables /∫ɛp/ and /∫æp/ under two conditions which differed in that vowel fundamental was controlled at 130 ± 5 cps in one condition. One group spoke the General American dialect while the second group spoke a subdialect, that of Altoona, Pennsylvania. Spectrographic recordings of the utterances were analyzed and the center frequencies of the lower two formants plotted. The plots of the two vowels were analyzed and the extent to which they overlapped described.
Within the limitations of this study, the results indicate that control of the speaker's vocal fundamental does not reduce vowel overlap, while controlling the subdialect of the speaker does reduce the percentage of overlapping. While overlap is decreased it is not eliminated, and it is probable that vowel discrimination is accomplished by means of cues additional to the frequency locations of the lower formants.
Onset of Ultrasonic Cavitation in Tap Water
Authors: Strasberg M. 
Published: September 2005

The conditions influencing the onset of acoustically-induced cavitation in tap water have been investigated, with special attention to the effect of air-filled cavitation nuclei. Cavitation was induced by exciting an acoustic radial mode in the water in a spherical resonator at a frequency near 25 kc/sec. Air-filled nuclei were detected by observing the reverberant decay of sound in the resonator at frequencies from 150 to 550 kc/sec, the presence of air nuclei causing an increase in the decay rate.
Measurements have been made of the sound pressure required for cavitation inception, and of the content of air nuclei, for the following treatments of the water: (1) allowing the water to stand undisturbed after drawing from the tap, (2) partially deaerating the water, and (3) subjecting the water to increased static pressure. Some measurements were also made of the threshold for rectified diffusion into air bubbles.
The experimental results have been compared with theoretical predictions based on three alternate forms of air nuclei: (1) free air bubbles, (2) air trapped in cracks on suspended solid particles, and (3) air bubbles surrounded by skins of organic impurities.
Absorption of Sound Arising from the Presence of Intact Cells in Blood
Authors: Carstensen Edwin L. , Schwan Herman P. 
Published: September 2005

The absorption of sound in blood occurs primarily on a molecular level and is related to the presence of protein in the cells and plasma. However, a small contribution to the total absorption arises simply from the presence of intact cells in the blood.
Analysis based on Epstein's theory of scattering shows that the cellular absorption results from a viscous interaction between the fluid and cells when the latter, because of their greater density, fail to follow the oscillatory motion set up by the sound wave.
Geometrical Theory of Diffraction in Inhomogeneous Media
Authors: Seckler Bernard D. , Keller Joseph B. 
Published: September 2005

The geometrical theory of diffraction is described. It is used to determine the diffracted fields in inhomogeneous media. Cases in which such media contain smooth convex bodies are treated. The theory employs an extension of Fermat's principle which yields diffracted rays. By energy considerations the field associated with each ray is calculated. This calculation requires the introduction of diffraction coefficients and decay exponents. General formulas for these quantities are given in terms of local properties of the medium and of the body.
In the companion article “Asymptotic theory of diffraction in inhomogeneous media” these problems are considered as boundary value problems. They are solved exactly and the solutions are expanded asymptotically for high frequencies. In all cases the asymptotic expansions agree completely with the corresponding results derived by the geometric theory, thus verifying this theory.
Velocity and Attenuation of a Narrow-Band, High-Frequency Compressional Pulse in a Solid Wave Guide
Authors: Redwood M. 
Published: September 2005

The usual solutions describing the propagation of continuous waves in solid plates and cylinders fail to predict the observed velocity and attenuation, and secondary signals, in the propagation of a narrow-band pulse of compressional waves of carrier frequency of the order of 10 Mc/sec. It is shown that all these factors may be accounted for if a slightly different form of solution is chosen, to fit more closely the conditions under which the propagation takes place. Both plates and cylinders are treated theoretically, and methods of obtaining approximate solutions of the modified frequency equations are discussed.
The results of this analysis agree closely with those derived by other, less exact methods, which commence with the assumption that the solid medium behaves very similarly to a fluid.
The relation of this work to the propagation of pulses at low frequencies is also discussed.
A method of analysis similar to that employed here is also necessary to predict experimental results in the propagation of pulses in multilayered wave guides of any configuration, mechanical or electromagnetic.
New Wall Design for High Transmission Loss or High Damping
Authors: Kurtze G. , Watters B. G. 
Published: September 2005

A typical single wall is characterized by a free flexural wave speed, cB, which increases with ω12. When cB approaches c0 (the speed of sound waves in the surrounding medium) the impedance of the wall to incident sound wave ceases to be mass-like because of the coincidence effect and the transmission loss will be less than that given by mass law. Since cB = (B/M)12(ω)12 for homogeneous walls, the deleterious effects of the coincidence of the flexural wave speed with the phase velocity of sound in the medium can be avoided for homogeneous walls by reducing the ratio of B/M. (B is the dynamic bending stiffness of the wall; M is the mass per unit area of the wall.) Thus the problem of good acoustical performance in homogeneous walls is seen to be in essential conflict with the need for structural rigidity.
A new wall design has been found in which the ratio of the static to the dynamic stiffness can be in excess of 1000:1 and where the stiffness changes from the static to the dynamic value in such a way that the acoustical behavior is nearly that of a perfectly limp wall. If desired, the loss tangent of the wall can be made large and nearly constant over a wide range of frequencies.
Transmission Loss of Some Masonry Walls
Authors: Watters B. G. 
Published: September 2005

The transmission loss of very large, single, solid walls is given by the “coincidence-effect” theory as presented by L. Cremer and others. The results of this theory have been compared with data from field measurements on some typical, masonry walls and are found to be in fairy good agreement. The differences which exist are believed to reflect the inapplicability of the theory to finite sized walls and the imperfection of the sound diffusion in the test rooms. An empirical design technique is presented which agrees more closely with typical field results.
The hollow masonry block walls which were studied behave much like solid walls with the same surface weight and bending stiffness. Laboratory techniques are described for measuring the physical constants of these and other materials.
Tests made on a typical lightweight aggregate masonry block show that the porosity through the block faces does not greatly reduce the transmission loss. However, painting such a block may increase the bending stiffness of the wall and slightly alter the transmission loss.
Isolation from Mechanical Shock with One- and Two-Stage Mounting Systems
Authors: Snowdon J. C. , Parfitt G. G. 
Published: September 2005

The damaging potential of mechanical shock experienced by resiliently mounted equipment is discussed in general terms. It is pointed out that the displacement, relative displacement, and acceleration of the mounted item, expressed as nondimensional quantities, describe the likelihood of damage in particular circumstances.
The performance of mounting systems has been judged by their response to a step-like shock displacement. The nondimensional quantities above have been determined as functions of the steepness of the leading edge of the step displacement for one- and two-stage, linear, viscously damped spring mountings. Heavy damping is beneficial in a mount in several respects, and its adverse effects on transmitted acceleration can be mitigated by the use of the two-stage mountings.
Semantic Reactions to Systematically Varied Sounds
Authors: Solomon Lawrence N. 
Published: September 2005

Noise bands simulating passive sonar sounds were varied in terms of spectrum (band passed from 150–600 cps, or 600–2400 cps, or 2400–9600 cps); in terms of amplitude modulation (simulated screw beats) at beat rates of 0, 3, 5, or 11 per second; and in terms of presence or absence of accent within a group of 4 beats. Every combination of these parameters (21 in all, not 24, since at zero beat rate there can be no accent) was rated by 20 subjects in terms of their aurally perceived characteristics on 15 scales representing seven different dimensions.
Analysis was made of the manner in which the 21 sounds clustered within the space defined by the seven psychological dimensions. Two major clusters of sounds were observed, differentiated primarily on the basis of band pass condition (high frequency vs low frequency). Exceptions to this general rule were analyzed to reveal the interactions between band pass condition, beat rate, and accent.
Attenuation and Regeneration of Sound in Ducts and Jet Diffusers
Authors: Ingard Uno 
Published: September 2005

The effect of noise regeneration by fluid flow on the performance of noise-attenuating structures is examined with special attention to muffler design. The insertion loss of a single element, as well as a continuous distribution of attenuating and noise-regenerating elements, is studied. For example, in a duct with an attenuation constant β per unit length and a regeneration r per unit length, the upper limit of the insertion loss is 10 log (2Eβ/r), where E is the source strength. It should be noted that the insertion loss of a noise-regenerating attenuator depends on the sound level to be reduced.
An analysis of experimental data on jet noise indicates that the power spectrum of a circular jet depends on frequency, f, and Mach number, M, approximately as f2M5 at low frequencies, as f−2.5M9.5 at high frequencies, and as M7 at the peak frequency. In terms of the corresponding jet spectrum, for which an empirical analytical expression is given, the maximum attainable insertion loss of a jet muffler diffuser is presented as a function of frequency. The deviation of the characteristics of a “lossy” diffuser from this upper limit depends on the attenuation and regeneration characteristics of the acoustical elements in the muffler. These characteristics are investigated for the special element consisting of a perforated sheet, and the results are applied to an analysis of the insertion loss of a muffler diffuser of the perforated basket type.
Model Experiments on Sound Propagation in Shallow Seas
Authors: Wood A. B. 
Published: September 2005

The experiments described deal mainly with the propagation of continuous waves of a particular frequency, and with the variation of signal strength with the depth of the receiver and the water using “point,” almost nondirectional, transducers. A simple method has been found for lining experimental model scale tanks to make them anechoic at the frequencies considered. It has been demonstrated that temperature changes and surface waves produce marked changes in sound propagation. More important influences, however, appear to be due to the nature of the bottom and the depth of the water.
Point-by-point observations, described in Sec. II of the paper, indicate that multiple reflections between the water surface and a hard reflecting bottom, like steel or concrete, result in the propagation of many of the higher modes or orders of reflection and the records of sound intensity variation from surface to bottom is covered with rubber (equivalent to mud and sand), however, the higher modes are suppressed and the records of surface to bottom intensifies are much simpler, containing relatively few maxima and minima. All these observations are in reasonable accord with either the mode theory or the ray theory.
It has been demonstrated also that the received signal (in all-round transmission and reception) is extremely sensitive to the depth of water. A change of depth of say 5 ft in water of depth 200 ft (full scale) may result in a change of the order of 30 db in received signal.
The distribution of the sound field on the bottom and surface of a water layer has been demonstrated by using sounds of relatively high intensity (Sec. III). Interference patterns form not only on the bottom but also on the surface of the water. A simple “abrasive” method has been devised which provides a permanent record of the sound pattern on the bottom.
A new scanning technique has been developed which gives a complete picture of a sound field of relatively low intensity, in a vertical plane either longitudinal or transverse in the water (Sec. IV) . In this method “point” transducers are used, one of which scans a vertical line several times a second whilst the other travels along or across the tank at a predetermined depth. The received signal modulates the cathode-ray oscilloscope spot which moves up and down in synchronism with the scanning transducer. The scan patterns reveal a striking difference between the two cases of a hard steel (rock) bottom and a rubber covered (mud and sand) bottom. The pattern for a steel bottom is very complex and contains many maxima and minima in each vertical scan. The rubber bottom, on the other hand, provides only a few maxima and minima at each scan. The patterns hitherto obtained are, however, not amenable to mathematical treatment. They confirm and amplify the results obtained by point-to-point methods described in Sec. II.
This method of scanning should prove a useful tool for further studies of low-intensity sound fields in water.
Acoustic Intensity Fluctuations and Temperature Microstructure in the Sea
Authors: Sagar F. H. 
Published: September 2005

The range dependence of variation coefficients has been investigated for each of eight selected experiments performed in New Zealand waters during midsummer for a variety of meteorological conditions. These experiments have employed 1.3-msec pulses of 14.5 kc sound from a projector of variable depth (40 to 100 ft). The pulses have been simultaneously received by a vertical string of six equidistant hydrophones (extreme depths 40 and 165 ft) and the square of the average variation coefficient V for the six hydrophones has been plotted against the range R to test for the eight individual experiments the applicability of the Mintzer fluctuation formula. This predicts for a medium exhibiting temperature microstructure that V2 ∝ R ⋅ f2α2a, where f is the frequency and α and a are, respectively, the rms values of the refractive index and the correlation length of fluctuation in the refractive index. An area was selected where the sea is fed by no rivers of any size, the depth varying with experiment from 40 to 200 fathoms. Drought conditions prevailed over the whole period of the work, and, as far as is known, no confluence of local ocean currents here produces microstructure. The latter if present should presumably be confined to surface layers and be due to diurnal insolation. One has hence selected for analysis those experiments performed during small swell and sea state in. (a) the early morning, (b) hot sunshine during the mid and late afternoons, (c) the mid afternoon during cool days with a completely covered sky, and (d) early evening after hot cloudless days. Close correlation exists between insolation and intensity fluctuations which follow the Mintzer dependence on range and the values of α2a obtained [(5.0–11.0)×10−7] are near the mean value reported by Sheehy (5.0×10−7.
The fact that the Mintzer formula is obeyed by case (b) only and the small values of V and independence of V upon R for the aforementioned conditions (a), (c) and (d) are interpreted to mean a diurnal cycle of growth and decay of insolation-produced microstructure in the surface layers of the sea in summer.