bluuebunny/crossref_metadata_2025 huggingface dataset:
Electromyography as a Speech Research Technique with an Application to Labial Stops
Authors: Lysaught Gloria , Rosov Robert J. , Harris Katherine Safford
Published: September 2005

Electromyographic techniques have been developed as indicators of the physiological processes of speech production. They provide a sensitive and direct means for describing the speech gesture in terms of the activity of the actuators rather than the consequent displacements of the speech mechanism. To the extent that perception is geared to articulation, this action pattern may be expected to yield simpler descriptions of the basic units of speech than have been available in acoustic or traditional phonetic terms (Franklin S. Cooper, Alvin M. Liberman, Katherine Safford Harris, and Patti Murray Grubb, “Some input-output relations observed in experiments on the perception of speech,” Proceedings of the Second International Congress on Cybernetics, Namur, 1958). This account attempts no more than a description of the experimental techniques and their application to a specific study of the English labial stops /p,b/. The electromyographic measures showed no significant differences in timing or amount of muscle activity at the lips between /p/ and /b/. In this pilot study, the electromyographic method has proved feasible and has yielded a partial description of /p,b/ that is simply structured and consistent with the acoustic-perceptual characterization of these sounds.
A Laminagraphic Study of Vocal Intensity
Authors: Hollien Harry , Curtis James F.
Published: September 2005

It has been suggested that vocal fold cross-sectional area (or mass) varies as a function of vocal intensity. Since this notion has not been subjected to test, it was the purpose of this investigation to study the relationship of the coronal cross-sectional area and mean thickness of the vocal folds to variation in vocal intensity. Subjects included eight males chosen on the bases of age, absence of voice problems, and the ability to produce specified vocal tones easily. The range of fundamental frequencies that each subject could produce was determined by a standard procedure. Final selection was made on the basis of these data and all subjects had essentially the same pitch ranges. Subjects were required to produce each of three vocal pitches at three vocal intensities. Pitches were specified in relation to total pitch range and were located as proportions above the lowest sustainable tone. The 10%, 25%, and 50% points to the nearest semi-tone were used but since all subjects' ranges were similar, frequencies of 104, 139, and 233 cps represented these levels. Intensities were specified as the 15%, 50%, and 85% levels of each subject's vocal intensity range. These proportions were obtained by requesting each subject to produce the loudest and softest phonations possible at each of the three frequencies. Vocal intensity was controlled by an Altex M40 microphone, a B and K calibrated amplifier, and SUI Model 11 sound level monitor. This system was calibrated by the GR 759-B sound level meter which was originally used to obtain the intensity ranges. Laminagrams were made of subjects phonating each of these vocal pitch-intensity combinations and measurements made of vocal fold cross-sectional area and mean thickness. Statistical analysis was carried out by an AXBXS three dimensional analysis of variance design on a IBM 610 computer. Briefly, the results permit the following conclusions: (1) As expected, vocal fold cross-sectional area and mean thickness were systematically reduced with increases in fundamental frequency of phonation. (2) Since the F for area was not significant at the 5% level but the F for mean thickness was, there is some question concerning whether there are systematic changes in vocal fold cross-sectional area as vocal intensity is varied. This question and limitations of the study will be discussed. (This research was supported by a grant from the National Institute of Health.)
Effect of Ultrasound on Osmotic Fragility of Canine Erythrocytes
Authors: Ackerman Eugene
Published: September 2005

Dilute suspensions of canine erythrocytes were exposed to 1 Mc focused ultrasonic fields with maximum acoustic pressures estimated at 10 atm. In standing wave patterns in which circulation was inhibited, the cells clumped rapidly at the nodes and no changes were found. With a free surface, fountaining and stirring occurred. Exposure at 1 atm ambient pressure then resulted in rapid lysis. Erythrocytes exposed briefly in isotonic Rous-Turner mixture and controls were both diluted with sodium chloride solutions of varying concentration. The optical density at 650 mμ was plotted as a function of salt concentration. The exposed samples showed a greater fractional decrease in optical density at low sodium chloride concentrations than did the controls. Other samples exposed in hypotonic solutions showed both the greater sensitivity to low sodium chloride concentrations and a smaller change in optical density as the sodium chloride was varied from isotonic to 70% isotonic. It has not been possible to demonstrate that any factor other than cavitation was responsible for the observed changes in osmotic fragility.
Cellular Changes Induced by Intense Ultrasound
Authors: Curtis Joseph C.
Published: September 2005

An extensive study has been made of the cellular changes occurring in mouse liver as a result of exposure to intense, focused ultrasound. In this study a broad range of doses of continuous and pulsed ultrasound have been employed. Groups of animals have been sacrificed at different times after irradiation and the exposed tissue examined, a number of cytological and histochemical techniques being used. Evidence of a selective action of pulsed ultrasound has been found both immediately after irradiation and at later times. This localized action is related to the histological organization of the liver and appears to selectively affect the parenchymal cells. Data on the relation of the amount of hepatic injury produced by ultrasound to several dosage parameters will be presented. The observed effects of ultrasonic action will be discussed in terms of the hepatic architecture and cell structure.
Noise Generated by Aircraft in Flight
Authors: McK. Eldred Kenneth , Rooney Thomas R. , Carmichael Richard F.
Published: September 2005

The generation of noise from turbulent boundary layers has been investigated both theoretically and by model experiments in recent years. However, until the present, no flight data have been available with the exception of high speed flybys. The paper presents results of several inflight measurements of aircraft noise including jet noise, wake noise, and a radiated boundary layer noise, obtained by flush microphones mounted in laminarized pods external to the aircraft. The data indicate that the radiated boundary layer noise is primarily of quadrapole origin at flight Mach numbers above 0.5, and further, that the inflight measurements are essentially in accordance with the ground flyby measurements when the effect of motion on the transmission of sound is considered.
Far-Field Noise Effects from Static Tests of the Saturn Booster
Authors: Dorland W. D.
Published: September 2005

The acoustic noise generated by the Saturn booster is characterized by the extremely large powers, broad directivity, low frequency power spectra, and low efficiency. Results obtained from a field survey of sound from the Saturn's initial series of static tests reveal some unique aspects of sound generated by clustered jet streams. Initial firings were of two and four engines each which produced acoustic powers of 0.56 and 1.6 megawatts, respectively. Corresponding acousthe efficiencies were quite low, being 0.03% for the two-engine test and 0.04% for the four-engine test. However, acoustic power radiated from eight-engine tests ranged from 25 to 40 megawatts, with an acoustic efficiency near 0.5%. Spectra from all tests peaked between 10 and 100 cps, and were rather ragged, showing severe dips near 250 cps and minor peaks at 1000 and 6300 cps. Directivity was quite broad in the eight-engine tests and much sharper in the two- and four-engine firings. While it is desirable to isolate cluster effects on noise generation it is difficult to do so because of the complicated jet deflector used on the tests.
Use of Helium and Steam in Acoustic Scale Model Jets
Authors: Morgan Walter V.
Published: September 2005

It is postulated that design of a valid acoustic model to simulate jet engine exhaust need consider only three exhaust gas parameters: Mach number, density, and velocity. This provides a logical basis for a simplified model testing technique which uses a convenient working medium other than that of the full-scale engine. Operation at reduced temperatures is the major benefit. The design of experiments using steam and helium as the working media to simulate military and afterburning conditions of a jet engine, respectively, is described. The experimental results of these tests and corresponding tests performed with heated air jets support the postulation. Conclusions concerning future applications of this technique are discussed. (This work has been supported by U. S. Air Force contract.)
Calibration Techniques Related to Vibration Pickup Use
Authors: Edelman S. , Jones E. , Smith E. R.
Published: September 2005

Review of recent publications indicates that current primary laboratory-calibration methods provide sufficient accuracy for present and foreseeable future needs. An upper frequency limit for vibration measurement was first indicated by Schloss. For usual levels, this sets a lower bound to the amplitudes needed in calibration. The use of resonant systems provides means for reaching large amplitudes as they are needed. Serious errors in calibration result from transverse shake table motion. Methods for monitoring motion exist, allowing elimination of this source of error. Shakers free of transverse motion are needed urgently. Development of means for accurate measurement of the transverse sensitivity of pickups at all frequencies of interest is needed also. Full exploitation of primary calibration techniques requires suitable comparison shakers and transfer standards. Available instruments are described. The need for an adequate transfer standard pickup and the characteristics of such an instrument are discussed. To detect damage in storage and attachment or loss of accuracy caused by structural conditions or in associated circuitry, pre-use calibration checks can be performed in a number of ways. Most available methods separate the pickup from the structure and are limited in frequency and amplitude. A new instrument described by Orlacchio and Schilling allows in-place checking of entire systems over wide ranges of frequency and amplitude. Some shortcomings of the method have been indicated by Pennington and alternatives have been suggested. Published advantages, objections, and inadequacies of each method are discussed. Also, we suggest comparison of the attached pickup with a detachable, laboratory-calibrated, transfer standard, both driven in place by a pulse.
Sound from the Action of Vorticity
Authors: Powell Alan
Published: September 2005

A formulation is suggested which shows how the sound from an aerodynamic flow can be primarily attributed to a volume distribution of dipole generators when a contiguous rigid body sustains a fluctuating fluid force. This can be interpreted in terms of the local fluid acceleration but, more significantly, can be attributed to the deformation of rings of vorticity in the flow (analogous to varying magnetic shells in electromagnetic theory). This leads to a new model especially applicable to aeolian- and edgetones. In the absence of a net fluctuating force, the sound from the vortex ring action degenerates from dipole to quadrupole nature. This situation is illustrated by considering the formation of a single vortex (of length l) from a length b of a thin layer of shear rate U, the distortion of the layer producing sound energy of the order of U7l2ba−5× (2.10)−4. (This is also accountable for by a longitudinal quadrupole generation according to Lighthill's theory.) This must be supplemented by a comparable amount of energy resulting from the dilatational effect due to the appearance of the low pressure core of the vortex. The acoustic power emanating from a succession of such vortices is roughly U8l2a−5× (2.10)−4. This point of view corresponds to the classical hydrodynamic result that the velocity (and hence pressure) at a point is derivable from a vector field (due to vorticity) together with a scalar field (associated with dilatation), except that time retardation effects must be recognized.
Development of Edgetone Theory
Authors: Powell Alan
Published: September 2005

The tone produced when the jet of air issuing from a small slit strikes an edge has provided “a battleground for rival theories” during the past hundred years. This paper traces the development of understanding of the phenomenon in the light of recent developments. Some of the earlier ideas were along the right lines; for reasons now apparent, they failed to produce close agreement with experiment, with the result that other ideas sprang up (especially as a result of experimental observations), some of which were to fade away. However, the suggestions of a “preferential wavelength” for the stream disturbance and of feedback have survived to provide the foundations for present theories. The feedback mechanism has been described in terms of pressure fields and hydrodynamics (vortex) fields; the latter outlook is further developed here to show how these “rival” viewpoints are actually in close accord. Thus, a century has passed before the true threads can be recognized and synthesized; the edgetone now enters a new era of quantitative study.
Stokes-Navier Equations and the Fundamental Equations of Flow Noise
Authors: Skudrzyk E. J. , Haddle G. P.
Published: September 2005

For ideal fluids, pressure may be considered to represent a function of the density that is defined by the state equation and the Euler equations. For viscous flow, variable pressure has to be replaced by the stress tensor. A scalar “pressure” no longer exists. The only scalar point functions that can still be retained for a viscous fluid are density and the trace of stress tensor (the average of the normal stresses in the three coordinated directions). The trace of the stress tensor and the density are, therefore, necessarily functions of one another. This conclusion makes it possible to expand (as Stokes has) the concept of pressure for viscous flow by defining it as the average value of the normal stresses. This generalized pressure is a function of the density and measures not the true stress in the fluid but the average of the stresses over all possible directions. In the classical theory of internal friction, the relation λ+23u=0 is wrongly impressed on the volume viscosity λ. In modern derivations, the volume viscosity λ is retained in its general form, but the pressure is no longer identified with a third of the exact value of the trace of the stress tensor. This situation makes it necessary to rederive the fundamental equations of flow and of flow noise; the derivations to be given are exact; the only assumptions that will be introduced are those of an isotropic fluid and of ideal fluid friction; the friction forces depend on the velocities only, and not on their higher-order time derivatives.
Investigation of the Precision of an Articulation Testing Program
Authors: Stuckey Charles W.
Published: September 2005

A mathematical model of the individual articulation scores of a team of listeners during their training period was developed. A similar model was developed for a fully trained articulation team. By contrasting the two models, statistical hypotheses of whether or not a team had had sufficient training were formulated, and a method of testing these hypotheses was evolved. To test the validity of this method of evaluating training, an articulation team was formed and trained. It was concluded that the method of evaluation is valid and that after 20 hr the team was fully trained in terms of the criterion adopted. The effect of memorization on the articulation scores was evaluated and found to be negligible. The maximum variance of a trained team was found, and the precision of the results was computed as a function of the number of repetitions averaged. By averaging the scores from a sufficient number of repetitions, any desired degree of precision may be obtained. An articulation team is proved to be a very precise and reliable measuring instrument for ranking voice-communications equipment in terms of degree of acceptability.
Phasor Analysis of the Stereophonic Phenomena
Authors: Bauer Benjamin B.
Published: September 2005

An improved understanding of the stereophonic phenomena may be obtained by use of acoustical pressure phasors to portray the sound pressures at the ears of the observer. Pressure phasors explain the existence and the nature of the virtual image formation by two loudspeakers, the effect of out-of-phase signals, the effect of observer head motions, the effect of being off the center of symmetry, and the action of a circuit for converting binaural earphones to stereophonic listening.
Extension of the Pressure Response-Frequency Characteristics of Condenser Microphones by Means of Carrier-Frequency Techniques
Authors: Koidan Walter , Magruder June O.
Published: September 2005

A method was investigated for extending the frequency range of microphone pressure calibrations to infrasonic and ultrasonic frequencies when the response at a single frequency is known. Assuming the microphone to be reciprocal, its pressure response is (u/i)p=0, where u is the diaphragm volume velocity, i the driving current through the electrical terminals, and p the sound pressure directly in front of the diaphragm. The diaphragm of a condenser microphone is driven by impressing a voltage across its electrical terminals, and its volume displacement is observed simultaneously by means of a carrier-frequency circuit. A substitution technique is then applied using a variable capacitance diode, which makes it possible to determine accurately the shape of the pressure-response curve as a function of frequency. No microphone other than the one to be calibrated is required. For frequencies at which the acoustic impedance of the microphone is not very much higher than its radiation impedance, the required acoustic termination is provided by a quarter wavelength tube. The experimental results are compared with coupler reciprocity calibrations performed from 1 cps to 20 000 cps. Limitations of the electrostatic actuator also are discussed, and a calibration method is described which uses a quarter wavelength tube in conjunction with an actuator to reduce the acoustic impedance seen by the diaphragm.
Low-Frequency Microphone
Authors: Barger J. R. , Witchey A. , Weinreb L.
Published: September 2005

This paper describes the design of a high-sensitivity low-frequency microphone. It has two basic components, a microphone element and a preamplifier. The microphone element is of the condenser type, using an edge-clamped stretched-Mylar diaphragm. The condenser microphone is used as one arm of a capacitance bridge which is furnished excitation by an rf oscillator. The bridge output is an rf signal modulated by the variations in microphone capacitance caused by pressure changes in the incoming signals. After suitable amplification, the modulated signal is processed in a peak detector. The resulting low-frequency signals are directly coupled into an emitter follower output stage. This pressure-sensitive transducer provides a useful output at pressure levels from 0.01 to 40 d/cm2 and frequencies of 0.1 to 100 cps. The frequency response of the microphone can be varied to suit system requirements by minor adjustments of either the microphone element or the preamplifier. Differences of phase shift between two or more microphones can be held to less than 1° at 20 cps. (The work reported herein was supported in part by a U. S. Army Signal Corps contract.)
Signal Presentation Rate and Auditory Vigilance
Authors: Martz Richard L. , Harris J. Donald
Published: September 2005

The probability of detection of visual signals by human observers in the vigilance situation has been shown to be a function of the rate at which signals are presented, where signals are given a high initial probability of detection along some (suprathreshold, intensity) gradient. This effect of signal presentation rate has not been directly demonstrated with auditory signals at threshold intensity. In a traditional vigilance design, six Navy men and six housewives gave aperiodic threshold determinations by Elliott's ascending method of limits for a 1000 cps tone in continuous broadband noise of 70 SPL during 48-min sessions. Following a 12-item pretest at the signal rate of 120 signals/hr, given at the beginning of each session to determine “relative zero,” subjects were individually tested on one of six signal rates (2.5, 7.5, 15, 30, 60, and 120 signals/hr) daily for six days, with coefficients of variation [(variance)12/mean] for intersignal intervals maintained at 1/15. Each determination involved n 2-db steps, where interstep intervals were approximately 5 sec, and no criterion or correction was set for false positives. Analyses of variance of mean relative intensity, latency, and distribution of false positive responses showed no consistent trends.
Information in Simple Multidimensional Speech Messages
Authors: Webster John C.
Published: September 2005

Simultaneous pairs of four-bit messages were presented to listeners at rates of two pairs every four seconds (4 bits/sec), three pairs every four seconds (6 bits/sec), four pairs every four seconds (8 bits/sec), and six pairs every four seconds (12 bits/sec). Each message of the pair was either [a] or [i], said by a male or a female, as a question (rising inflection) or a statement (falling inflection), and heard in either the right or the left ear. Sequences were made that were balanced (1) between ears, (2) between male and female voices, (3) between [a]'s and [i]'s, and (4) between questions and statements. The subject sometimes listened to both messages but usually listened only for the messages (1) in one ear, (2) of one voice, (3) of one vowel sound, or (4) of one inflection pattern. In each case he categorized all four dimensions. The best subject could receive correctly about six bits per second whether this was one of two messages at the 12 bit/sec rate or both of two at the 6 bit/sec rate. It was easiest to separarate messages by ear, followed by voice (male or female), and vowel. It was difficult to separate or classify messages by inflection pattern. (Carried out at Applied Psychology Research Unit, Cambridge, England, on a National Science Foundation fellowship.)
Determination of Elastic Constants of Isotropic Materials at Megacycle Frequencies
Authors: Meeker Thrygve R. , Meitzler Allen H.
Published: September 2005

The frequency dependence of the phase and group velocities for longitudinal and flexural waves in a plate provides the basis for several convenient methods of determining elastic constants. In these methods two independent elastic constants are determined in strip-shaped samples from measured values of certain special frequencies and delay times. One set of data is determined by the frequencies at which certain pairs of modes have either equal group or phase velocities. At other frequencies the delay vs frequency characteristics of various modes have extrema, and the frequencies at which these occur along with the measured delays provide another set of data. Theoretical calculations have been carried out which show the dependence of these measured quantities on Poisson's ratio. The shear wave velocity and Poisson's ratio are determined for a sample behaving essentially as an isotropic, elastic solid by selecting values that bring calculated and measured quantities into agreement. The methods to be discussed are capable of detecting anisotropic or anelastic behavior if either or both of these complications are present and have been used successfully at frequencies up to 35 mc.
Ultrasonics Measurements of the Photoelastics Constants of ADP
Authors: Achyuthan K.
Published: September 2005

An Ultrasonic technique, first suggested by Mueller [Z. Krist, A99, 122 (1938)], has been used to determine the ratios P12/P11, P13/P33, P31/P11 of the photoelastic strain constants of ADP crystals. These values, along with the values of some of the stress (Carpenter, Ph.D. thesis, Harvard University, 1951) and elastic constants, have been used to determine a complete set of photoelastic constants. Accuracy of the measurements will be discussed. (This work was supported by the National Science Foundation.)
On the Derivation of Molecular Information from Ultrasonic Relaxation
Authors: Piercy J. E.
Published: September 2005

A review of energy differences ΔE between rotational isomers of eight ethane derivatives reveals almost no correlation between recent apparently reliable ultrasonic values and those available from other techniques. The properties of the eight molecules have therefore been examined to ascertain how closely they conform to the hopeful assumptions inherent in the usual methods of deriving ΔE from the ultrasonic measurements. The normal neglect of the difference in dipole moment and volume between isomers and assumptions concerning undetermined static parameters are found to introduce errors in the derived values of ΔE which are at least the same magnitude as its absolute value. Similar errors may also he expected for other isomeric systems, and some are probably unavoidable for measurement in pure liquids, but can be avoided in favorable cases by solution measurement. Perhaps the most interesting discovery is the error which results from deviations from ideal mixing caused by a difference in dipole moment between isomers and the use of the Herzfeld-Kneser formula for thermal relaxation, which assumes ideal mixing. Much larger errors may be expected to result from nonideal mixing in the use of the Hall formula for structural relaxation in associated liquids.
Ultrasonic Temperature Determinations in a Plasma
Authors: Carnevale E. H. , Poss H. , Yos J. M.
Published: September 2005

An ultrasonic pulse technique, similar in principle to that developed by Livengood, Rona, and Baruch [J. Acoust. Soc. Am. 26, 824 (1954)] for measuring gas temperatures in an internal combustion engine, has been used in determining the temperature of an electric arc plasma jet. Measurements of sound velocity at 1 mc/sec were obtained in high temperature air, argon, and helium at atmospheric pressure using a Model 500 Avco plasma generator. Temperatures were calculated from these sound speeds on the assumption that only the translational and rotational degrees of freedom were excited by the sound wave, while vibration, dissociation, and electronic excitation remained frozen. The temperatures determined in this way ranged from 3500 to 8000°K. In the case of the air arc, the ultrasonic temperature measurements were compared with temperatures determined from an energy balance on the plasma jet. The average temperatures obtained by the two methods agreed within 10% over the temperature and enthalpy range considered. The results also showed that temperature fluctuations as high as 50% can occur during a given arc run. A discussion of the experimental apparatus, method of measurement, experimental results and analysis will be given.
Cochleo-Tympanic Reflex Tests with Controlled Acoustic Stimuli
Authors: Mendelson E. S.
Published: September 2005

In repeated tests on one subject, drumhead retractions were recorded from one ear while the other ear was stimulated acoustically. The amplitude and the spectral constitution of the stimuli were varied; the rise time for each stimulus remained constant. With the following stimuli: masking noise, 128, 256, 512, 1024, 1448, 2048, 2896, 4096, 5792, and 8192 cps, the apparent reaction thresholds averaged about 105, 115, 120, 110, 110, 110, 100, 95, 110, 105, and 115 db (re 0.0002 microbar), respectively. On different occasions average threshold estimates varied within ±10 db, whereas the contours of the stimulus-response magnitudes at the individual frequencies tended to be parallel from day to day. In every experiment the relative peak magnitudes of the reactions to 128, 4096. 5792, and 8192 cps were smaller than those to midfrequencies and noise. The appearance of the recordings obtained with the individual stimuli also suggests a systematic variation with spectral quality. The present indications are, however, obscured by uncertain acoustic and biological complexities, and call for further study.
Damage Risk Criterion for and Auditory Fatigue from the Audiac
Authors: Kryter K. D. , Weisz A. Z. , Wiener F. M.
Published: September 2005

Approximately three years ago Dr. Wallace J. Gardner and Dr. J. C. R. Licklider invented a device, later named the Audiac, which apparently has certain analgesic effects when used in dentistry. For this purpose the Audiac provides to the patient's ears wide band noise and music. The intensity levels of the noise and music are, within certain limits, under the control of the patient. Before the first production model of the Audiac was made generally available, instructions and advice for its use with regard to possible damage risk to hearing were written. These instructions, based on a specified spectrum for the noise to be provided by the Audiac, were in part aimed at the prevention of an exposure to the noise and music beyond a specific damage risk criterion. This criterion was based on scientific data appearing in the medical, physiological and acoustical literature on the subject of temporary and permanent hearing loss due to exposure to sound. The purposes of the present paper are (1) to review briefly this damage risk criterion, (2) to present the results of laboratory tests conducted to measure the auditory fatigue caused by the noise and music from the Audiac, and (3) to compare the amount of temporary auditory fatigue observed in our tests and the fatigue one would predict according to our criterion, and according to recent mathematical formulas derived for this purpose by Ward, Glorig, and Sklar [J. Acoust. Soc. Am. 31, 522–528 (1959)].
Psychopathologic Mechanisms in Aversive Responses to Noise
Authors: Ostwald Peter F.
Published: September 2005

The purpose of this presentation is to specify certain forms of breakdown in the human “survival-scheme” which, in combination with acoustic factors, can make noise intolerable. Twelve mentally-ill persons, ranging in age from 14 months to 80 years, and 7 normal volunteers were studied, using Wilmer's Auditory Projection Technique [Science (1951)] and other tape-recorded stimuli. Listener responses were studied in terms of verbalized labels for the imagined acoustic event, ideas about the internally felt impact of the sound, and statements about externally observable behavior. Dreams and hallucinations were noted whenever possible. The results were analyzed within a theoretical framework proposed by D. M. Green [J. Acoust. Soc. Am. (1960)], viz., that the listener's “criterion-level” is a significant determinant in decision-making phases of the threshold process. Assuming that listeners scan their environment for meaningful auditory signals, a noise seems to become disturbing when it simultaneously stimulates and frustrates the listener's search for nourishment, protection, contact, and pleasure. The intensity of each of these needs and the completeness with which it can be satisfied depend on multiple genetic, personal, and social factors. Therefore, it is suggested that effective medical noise-desensitization methods might be developed to augment the already successful acoustic approaches to noise control.
Shifts in the Masked Threshold
Authors: Hirsh Ira J.
Published: September 2005

Unpublished observations by Michel Burgeat in 1958 have now been repeated and extended. When the typical masked threshold of a tone is measured in the presence of a white noise, it is very stable over time. When, however, remote masking is measured for low-frequency tone in the presence of a high-frequency band of noise, initial threshold just after the noise is turned on is higher than it is subsequently. This reduction in remote masking takes place in from 1 to 3 min depending upon the noise level. The amount of shift varies from 1 or 2 to as much as 10 or 12 db. A similar shift is shown even for the threshold of the low-frequency tone measured on the ear opposite to the one receiving the noise. This second observation casts some doubt on the relevance of the remote-masking process for this shift. Interpretation involving the acoustic reflexes will be discussed.
The Effect of Matching Time on Perstimulatory Auditory Adaptation
Authors: Small Arnold M. , Minifie Fred D.
Published: September 2005

If perstimulatory adaptation is measured in terms of a loudness balance between the ear (experimental) undergoing sustained stimulation and the contralateral (comparison) ear, it has been assumed that the shorter the duration of the comparison stimuli the more accurately the loudness balances will reflect adaptation in the experimental ear. That is, the shorter the comparison stimuli the smaller the amount of adaptation in the comparison ear itself. This study attempted to provide information regarding the nominal perstimulatory adaptation when both the duration and the interval between comparison stimuli were varied systematically. The experimental stimulus consisted of a 4000 cps tone at 80 db SL. The comparison stimulus was a tone of identical frequency derived from the same oscillator whose intensity was controlled by the listeners through a motor driven attenuator. Both the on and off times of the comparison stimulus were varied from 10 to 60 sec in 10-sec steps. The results indicate that as either the comparison stimuli are shortened or interstimulus interval lengthened, the amount and rate of measured adaptation increase. The maximum adaptation rate approximates 20 db/min and occurs immediately following initiation of the experimental stimulus. Under most conditions adaptation reaches an asymptote by about 6 min, the maximum amount being about 30 db. Under equivalent conditions, changes in on time produce greater changes in rate and amount of adaptation than do similar changes in off time.
Linearity in Nonlinear Response and Its Application to Acoustical Fatigue Investigations
Authors: Wang Paul
Published: September 2005

Experimental studies were performed on simple structural elements subjected to sinusoidal and random noise excitations in both linear and nonlinear response regions. On the basis of results obtained, a theory is formulated to account for the observed nonlinearity and to explain the possible factors causing sudden amplitude changes inherent in skewed response peaks identifiable to nonlinear cases. By using familiar resonance equations of one degree of freedom, an alternative approach is offered and compared with current understandings of acoustically induced stresses under high level excitation. Sample results will be employed to illustrate the feasibility of applying these findings to fatigue life expectancy calculations for random loading. The methods used in determining damping coefficient ratio will also be discussed.
Evaluation of Dynamic Characteristics of Resilient Materials
Authors: Vatz I. P.
Published: September 2005

The problem of experimentally determining the dynamic characteristics of resilient vibration isolation materials has been solved using two techniques. The test methods, instrumentation and the readouts in terms of impedance and transmissibility are described. Results of impedance and resonance analysis are discussed for several sample materials under different degrees of loading. The results are compared with theoretical values. Static values for materials with high hysteresis are also given in terms of standard stress-strain curves. The differences between static and dynamic spring constants are discussed.
Damping of Flexural Waves by “Patches” of Treatment
Authors: McQuillin R. J. , Kerwin E. M.
Published: September 2005

The damping of vibrating systems by uniform applications of damping treatments has been discussed earlier [J. Acoust. Soc. Am. 31, 952 (1959); 32, 912(A) (1960); 32, 1513(A) (1960)]. However, in some practical applications only a part of the system may be available for treatment. The question of partial coverage is also raised when treatment weight is an important consideration. The present studies present the first step toward describing the effectiveness of partial treatments or “patches.” We consider a system (beam or plate) having a one-dimensional standing flexural wave of the form A coskx. We consider both free-viscoelastic-layer and constrained-viscoelastic-layer damping treatments. Damping effectiveness is evaluated as a function of patch length, patch position in the standing-wave field, shear parameter, viscoelastic material loss factor, and constraining-layer boundary conditions. The concept of a damping efficiency for the patch is introduced. Thus, for a given system the damping can be evaluated as the product of the fractional surface coverage and the damping efficiency. (Supported by the U. S. Navy, Bureau of Ships.)
On Defining the Range of Pitch Perception
Authors: Guttman Newman
Published: September 2005

In stating that pitch is an attribute which may be ordered on a high-low scale, the American Standards definition refrains from setting frequency limits to pitch perception. This may be due to fear that presence of harmonics arising out of distortion of low-frequency sinusoids makes responses in this region incompatible with responses to high-frequency sinusoids. We suggest that inasmuch as 200–400-cps unipolar pulse trains with or without fundamental component produce essentially the same pitch perceptions as sinusoids, such trains may be used to examine low pitches without frequency restrictions. Perhaps then it becomes justifiable to confine pitch perception by definition to a range from the highest perceivable frequencies to the low frequencies where the high-low dimension slides into the fast-slow dimension. It may furthermore be useful to revive the idea of defining an extent of musical pitch within the over-all range. We might assign the presence of the octave as the criterion of this extent. The upper limit of musical pitch is about 4500 cps, and our tests of the octave with pulse trains place the lower limit at about 35 cps.
Synthesis of the Steady-State Equivalent Circuit of a Piezoelectric Electroacoustic Transducer
Authors: James D. B.
Published: September 2005

Prior to the writing of this paper, it has been difficult to determine an accurate equivalent circuit for certain piezoelectric transducers, particularly for BaTiO3 disks 3 in. in diameter and from 0.1 to 0.25 in. thick. It was discovered that the methods currently in use for finding a steady-state equivalent circuit for these disks, yield results that are highly inaccurate, and, therefore, useless. In all cases, these disks were tested in the thickness-resonance mode. An equivalent circuit for a BaTiO3 transducer has approximately the same impedance as the transducer over a narrow band of frequencies near the mechanical resonance of the transducer. Near the mechanical resonance of the transducer, the impedance locus in the complex plane is circular. The problem can be approached as a 2-terminal network-synthesis problem. The equivalent circuit consists of linear, bilateral, passive elements, and is derived from the impedance circle. The mechanical-resonant frequency can be found from the equivalent circuit. All of the transducers tested had prepolarized barium titanate or lead zirconate titanate elements, were pressure-release mounted, and were operated in the linear region without bias. [This work was sponsored by the Bureau of Ships under Contract No. NObsr-72627.]
Investigation of Computational Techniques for Prediction of Far-Field Radiation Pattern of a Transducer from Near-Field Measurements
Authors: Ricard J. H. , Lindman M. W.
Published: September 2005

The far-field acoustic-radiation pattern of a large single-frequency cylindrical transducer was computed, using various methods, employing data taken in the near field of the transmitter. Beam patterns thus computed are compared to the measured far-field beam pattern from the same transmitter. Two ground rules were imposed on this study: (1) No assumptions would be made as to any relationship between the pressure and its gradient which cannot be justified theoretically. (2) Any approach which led to the equivalent of the spheroidal wavefunction method would not be considered further, unless the formulation was such that the computation time involved was considerably less. The Kirchhoff-Helmholtz formula, using both the measured pressure and pressure gradient, gave the best agreement with the measured far-field directivity. Poorer agreement was shown when the wave equation was approximated by a difference equation, using the measured pressure and its gradient as boundary conditions, and calculating the pressure step by step from the near field to the far field. Other methods employed for calculating the far-field pressure were found to be inadequate.
Effects of Spectral Components, Duration, and Rise Time of Sound on Perceived Noise Level
Authors: Kryter K. D. , Pearsons K. S.
Published: September 2005

Laboratory studies were undertaken: (1) to validate, if possible, equal noisiness contours for bands of noise and to extend the range of these contours to higher sound frequencies; (2) to determine the effects of the presence of intense pure-tone components in wide-band noise upon judgments of loudness and noisiness; and (3) to equate the effects of rise time, duration, and decay time of a sound upon its judged noisiness. The data indicate that: (1) Presently published equal-noisiness contours have the proper shape, or nearly so, up to about 6000 cps. An extension of the contours is proposed for use with sounds having higher frequency components. (2) The presence of strong pure-tone components in a background of broad-band noise has a much more dramatic effect on judged noisiness than judged loudness. (3) It appears, from a preliminary study, that the trading relation between over-all duration (212 to 20 sec) and peak sound-pressure level, keeping rise- and decay-time ratios constant is fairly well represented by the “equal energy” rule—i.e., halving the total duration reduces judged noisiness to the same degree as a 3-dB reduction in sound-pressure level. The relation of these findings to procedures for the calculation of perceived noise level is discussed. [This work was jointly supported by the National Aeronautics and Space Administration and by the Federal Aviation Agency, under Contract NASr-58.]
Importance of Instructional Set to Psychoacoustical Scaling
Authors: Rule Stanley J. , Little John W.
Published: September 2005

Carefully presented instructions are a basic requirement of successful psychoacoustical scaling studies. The term in the instructions which refers to a subjective experience uniquely defines the type of scale constructed. This paper describes the degree to which a psychoacoustical scale would be modified by changes in instructions. The results of 2 studies are reported. The first discusses the differences in subjects' responses to instructions based on 3 different key words—loudness, noisiness, and annoyance. The second is concerned with the effect on subjects' responses of mixed instructions (i.e., where more than one key word appears in a single set of instructions). The results indicate that different instructions “set” subjects to give different emphasis to various physical aspects of sound, and that instructions based on a combination of 2 key words yield ratings significantly different from ratings given to the same sounds when the key words are used individually. A recommendation is made that instructions be selected which set subjects to emphasize sound dimensions relevant to particular noise problems.
Interpretation of Sound Velocity Profiles in Sea Water
Authors: Morey Carl F.
Published: September 2005

Interpretation of the principle features of sound velocity in terms of the basic oceanographic parameters—temperature, salinity, and depth—is undertaken using the functional relationship between the velocity of sound and the temperature, salinity, and pressure of the sea water through which the sound is propagating as expressed by Wayne D. Wilson of the U. S. Naval Ordnance Laboratory. The effect of independent variation of these parameters on the sound-velocity profiles is treated mathematically for a uniform and a stratified ocean. The slope, slope reversals, kinks, and minimums in the sound-velocity profiles are related to environmental conditions. A comprehensive discussion of the causes of the long- and short-term changes in the features of the profiles is included. The use of sound-velocity data to infer primary oceanographic parameters is demonstrated using the temperature-salinity relationships.
Statistical Model for Investigating the Physical Parameters of the Ocean
Authors: Shaffer Robert L.
Published: September 2005

The dynamic behavior of a gas or liquid is determined by the conservation equations for mass, momentum, and energy, together with the equation of state. These equations with certain restrictions have been investigated in some detail. The 3 cases that have been considered in solving these equations for the physical parameters of the medium are: (1) no energy source put into the medium, (2) a deterministic energy source put into the medium, and (3) an undeterministic energy source in the form of Gaussian white noise put into the medium. In the 1st case, an expression for the temperature distribution as a function of boundary conditions is obtained. In the 2nd and 3rd cases, a statistical solution is obtained. The 2nd case leads to an expression for the expected value of the temperature fluctuations, and the 3rd case gives expressions for the physical parameters of the medium in terms of the Wiener statistics.
Verification of Attenuation and Ambient Noise in the Ocean
Authors: Blickley L. F. , Ayres A. U. , Curzan P. C.
Published: September 2005

The attenuation of acoustic energy in the ocean at a frequency of 40 kc was measured by means of a bottom-mounted array of 7 hydrophones in 1800 ft of water. The source of short pulses was a ship-mounted projector. Measurements were made by determining the peak amplitude of the received pulses as a function of range. Spherical transducers were used to minimize the effect of patterns on the measurements. These measurements agreed with the unpublished values obtained by APL, Washington. In addition, the ambient sea noise as a function of sea state was measured. The values obtained, when corrected for the attenuation over the depth of 1800 ft, agree with published values within 12 dB from sea state 3 down to below sea state 1, where system noise became predominant.
Sound Absorption in the Ocean as a Function of Temperature, Salinity, and Frequency
Authors: Beam John P.
Published: September 2005

The salinity and temperature dependence (the latter being significant mainly at lower frequencies) of the quantity A in Lieberman's equation α=βf2+(Af0f2)/(f02+f2) for sound absorption in the ocean bare been obtained by the use of data contained in publications by Kurtze and Tamm and by Wilson and Leonard. Using the values for pure water absorption βf2 and for the power relaxation frequency f0 used by Del Grosso, the predicted absorptions for various frequencies f agree with the careful measurements of Murphy, Garrison, and Potter made in Dabob Bay in 1958.