bluuebunny/crossref_metadata_2025 huggingface dataset:
Psychic Factors in Hearing Loss
Authors: Farley Jane , Derbyshire A. J. , Carter Richard L. , Mills Peter J.
Published: September 2005

A pilot study illustrates the design, and suggests working hypotheses, for a research aimed at specifying the psychic factors which may predispose, cause, or contribute to inefficiency in the use of available auditory information, at any point in the hearing act (defined as the sequence of events from the impingement of the stimulus on the tympanum—to the subject's meaningful responses to that stimulus). Definitions, and theories relating these definitions are offered, and a rationale and procedure for the testing of these theoretical formulations is demonstrated on seven subjects. These subjects are intensively studied, by medical, audiometric, and social investigation, during a week of hospitalization, and are also given a battery of objective and clinical psychological tests. It is felt that the concepts and definitions of the various events in the hearing act, as presented in this pilot study, provide points of contact between the traditionally (and artificially) separated approaches of psychically-oriented investigators and those whose primary area of interest is somatic and neurological; i.e., the theoretical model herein proposed can be operationally defined in medical and psychological terms simultaneously. Psychic hopotheses are restricted to those for which neural mechanisms can be demonstrated, and somatic and neural hypotheses are similarly limited to those which do not violate psychic function. Hypotheses are tested, concerning the psychic availability, necessity, and maintenance of auditory loss, as an adjustive mechanism, and in general are supported by independently analyzed audiometric indicators of “psychogenicity.” [The research was supported by the National Institutes of Health (NIMH Research Grant ♯M2270(Cl)), and all audiometric work was done under the direction of William Waldrop, Director of the Speech and Hearing Service at Presbyterian-St. Luke's Hospital in Chicago.]
Determination of the Velocity of Sound in Distilled Water
Authors: Brooks Richard
Published: September 2005

The velocity of sound has been determined in distilled water over the temperature range from 23°C to 30°C. The method used consists of measuring the time delay, associated with two different path lengths, measured between the crystal faces of two barium titanate transducers. Coupled with an accurate measure of the length the velocity is determined from the quotient of Δl/Δt. It is believed that the accuracy of the measurements is less than ±1 ft/sec.
Measurement of the Adiabatic Elastic Moduli of Alpha Uranium as a Function of Temperature
Authors: McSkimin H. J. , Fisher E. S.
Published: September 2005

The elastic moduli of alpha uranium have been measured as a function of temperature in the range −195 to +300°C for c11, c22, c33, and from −195 to +25°C for the remaining moduli. An ultrasonic technique previously described was used [IRE Trans. on Ultrasonic Eng. PGUE-5, 25 (1957)]. As computed from the best fit polynomials the temperature coefficients in parts per million per °C at 25°C are c11: −56.9, C12: +327, c13: +629, c22: −251, c23: −123, c33: −378, c44: −558, c55: −1064, c66: −623. A maximum occurs for c11 at −17.2°C and a minimum occurs for c13 at −66°C. The volume compressibility passes through a minimum at approximately −100°C. [Refer to J. Appl. Phys. 29, 1473 (1958) for 25°C values of moduli.] (This work was carried out in part under the auspices of the U. S. Atomic Energy Commission.)
Orchestra Enclosure for the Henry and Edsel Ford Auditorium in Detroit, Michigan
Authors: Johnson F. Russell , Beranek Leo L. , Klepper David L.
Published: September 2005

The Ford Auditorium, designed as a multipurpose hall and completed in 1957, exhibited certain acoustical deficiencies when used as a concert hall. The reverberation time was considerably below the optimal range for orchestral music; potentially useful sound energy was dissipated in a very large stage house which had little separation from the orchestra; the organ grille of (undamped) aluminum bars resonated at note “d1”; and further problems were created by the location of the fixed organ. This paper describes steps taken recently to improve the characteristics of the hall for music. A mechanically demountable, plywood enclosure was designed with surfaces oriented to diffuse sound and distribute it to the performers and the audience. Other measures included damping of the bars in the organ grille and elimination of a large fraction of the sound-absorptive material that was in the hall. Following modification, the reverberation time at different frequencies was increased by amounts tip to 0.6 sec above previous values. Results of the acoustical measurements and listening tests are discussed in the paper. The architect was Crane, Kiehler, and Kellogg.
Sound Localization
Authors: Hanson R. L.
Published: September 2005

When one listens to a transient type signal from two equidistant loudspeakers in free space, he experiences the sensation of a single well-defined source. The apparent position of the source can be altered by adjusting the relative outputs of the two speakers, by delaying the signal from one or by a combination of level and delay adjustments. If the transient type signal is replaced by a steady-state single frequency tone, the virtual source is again well-defined and can be changed in azimuth position by altering the speaker outputs as long as the two sources are in phase. However, as one source is delayed the virtual source becomes indistinct and localization becomes difficult. Tests will be described which indicate that when one listens to a steady-state single frequency tone, as from a pair of sources in free space or from a single source and its images in a room, he experiences the sensation of a well-defined single source only when the resultant time and pressure differentials correspond to those which could result from a single source in free space. This indicates that the apparent position of a steady-state single frequency source in a room bears a rather complex relation to the position of the actual source. Correct localization is dependent on transients in the signal and may be influenced by visual cues.
New Stereophonic Projection Console
Authors: Bauer Benjamin B. , Sioles George W.
Published: September 2005

The simplicity and convenience afforded by a single instrument has proven to be an important factor in stereophonic sound reproduction in the home. A new stereophonic projection console has been developed, based upon practical directional properties of loudspeakers. The stereophonic projection console provides satisfactory separation of left and right sounds by reflection from the room boundaries. Measured performance characteristics and subjective evaluation of the system will be presented.
Susceptibility and Sex
Authors: Ward W. Dixon , Glorig Aram , Sklar Diane L.
Published: September 2005

Hearing surveys invariably indicate that women have more sensitive hearing than men, the difference increasing with age. This is generally attributed to the fact that women are, on the average, exposed to less noise and gunfire than are men. A possible alternative, however, is that women are less susceptible than men: that in the same noise environment, men will suffer more permanent loss than women. If this were so, one might expect the same to be true of temporary threshold shift (TTS). Therefore the effects of one hour of exposure to 100-db 1200-24OO-cps noise were determined for two groups of normal-hearing college students: 15 men and 15 women. There were no significant differences, either in growth or recovery of TTS at 3 and 4 kc, between the groups. These results strengthen the hypothesis that differential exposure, rather than differential susceptibility, is responsible for the observed differences in auditory sensitivity between men and women. (Research supported by research grant B-1122 from the National Institutes of Neurological Diseases and Blindness, Public Health Service.)
Effect of a Loud Pre-Exposure Tone on TTS Resulting from Impulse Noise
Authors: Fletcher John L. , Riopelle A. J.
Published: September 2005

Previous studies have shown the action of the acoustic reflex damps transmission of loud sound through the middle ear. These studies indicate latency of the reflex prevents it from providing protection for impulse noise because of the sharp rise time of such sounds. If the reflex could be activated prior to exposure to such sound, it should protect the ear from overload. To test this hypothesis, 24 subjects were exposed to 100 rounds of fire from .30 caliber machine gun (one round at a time) under two different experimental conditions. Time between rounds varied randomly from 2–6 sec. Under one experimental condition a 1000 cps 100 db tone was presented 200 msec before each round, ceased when the gun had fired. The other condition entailed exposure to the firing without the pre-exposure tone. The TTS's resulting from exposure under the two conditions were compared to determine the effect of the pre-exposure tone. Results show that the pre-exposure tone condition produced significantly smaller TTS, as predicted, than those obtained in the absence of the tone. These findings were related to previous literature.
Influence of Loud Contralateral Stimulation on the Threshold for Lower Frequency Tones
Authors: Loeb Michel , Riopelle Arthur J.
Published: September 2005

Several studies have indicated that exposure to loud sounds activates a reflex which acts to damp sound transmission through the middle ear. Recent work by Fletcher and Riopelle demonstrated that subjects exposed to a tone loud enough to activate this reflex, and immediately afterward exposed to intense impulse noise, exhibit appreciably less TTS than when the activating tone is omitted. This study attempted to measure the amount of attenuation produced during stimulation by a 100 db, 2000 cps tone in the opposite ear by measuring monaural shift in threshold, ascertained by a tracking procedure. Test tones were 100, 500, and 1000 cps. (Previous investigators found that appreciable reductions in cochlear microphonics for these frequencies were produced by the acoustic reflex. The protection from impulse noise was observed at or below 1000 cps. Moreover, no masking from the stimulating tone would be expected.) Small consistent reductions in sensitivity (less than 5 db) occurred during contralateral stimulation; these changes rarely persisted as long as 90 sec. Changes observed were nsufficient to account for the reductions in TTS afforded by the stimulating tone in Fletcher and Riopelle's experiment. Explanations for this discrepancy and for the changes observed are discussed.
Image Summation in Shallow-Water Sound Propagation
Authors: Urick R. J.
Published: September 2005

Shallow-water sound propagation is often described in terms of normal mode theory in which the sound field is given as the sum of normal modes. Much less work has been done on the counterpart of this theory—image theory—probably because of the formidable task of summing the many images required. In this paper such image sums were obtained with a digital computer, and sets of transmission curves were obtained for various frequencies and water depths. For ease of computation, the reflection coefficient was first taken to be independent of angle; when compared with field data, the computed curves were found to fall off too fast with range. Better agreement was had under the more realistic assumption of unity reflection coefficient within the critical angle and zero beyond. Comparison with measured transmission runs selected at random in widely separated areas show that the agreement with the field data is often good. Yet there are many instances of wide divergence between the predicted and observed transmission that must be the result of the over-simplified bottom conditions necessarily assumed in the theory. The prediction problem in short-range shallow-water sound transmission is still essentially unsolved.
Importance of Sound Insulation in Residential Architecture
Authors: Doelle Leslie L.
Published: September 2005

Considerable developments and changes are taking place in the technology of residential building constructions, as for instance the increasing number of applications for new, lightweight building materials, the frequent use of prefabricated building constructions as well as framed and paneled skeleton structures, the necessity of saving in building materials, etc. These circumstances in addition to the increasing number of noise sources and the many regrettable acoustical misconceptions in architects' circles have practically banished acoustical comfort from residential buildings. Those architectural-, mechanical-, and structural-acoustical principles are reviewed which must be considered when planning noise-free residential buildings. A complete plan for a noise-control by law has been worked out which could be interpolated into the current building regulations, taking into consideration technical and economic aspects as well as local requirements. Steps must be taken in the scientific and practical field in order to promote acoustical testing of the new building constructions in both the laboratories and in the erected buildings alike. The idea of sound-insulated residential buildings has to be propagated in a more effectural manner in the press, radio, TV, by exhibitions, and model constructions.
Consistency of Repeated Laboratory Measurements of Sound Transmission Loss
Authors: Huntley Ralph
Published: September 2005

A short report on measurements made at three laboratories on a three-inch thick poured concrete wall and on measurements made at Riverbank Acoustical Laboratories on identical walls and walls built to the same specifications.
Analysis of Sequential Decisions
Authors: Green David M. , Swets John A.
Published: September 2005

At the Washington meetings a year ago, we presented data showing that, at least on a macroscopic level, the statistical theory of sequential decision as developed by Wald provides a good description of the behavior of human observers in a sequential detection task. In a sequential decision task the observer makes as many observations as he chooses before deciding whether the sequence of observations arose from noise or from signal plus noise. The datas howed the error rates and the mean number of observations preceding a terminal decision to vary appropriately with changes in the values associated with the various decision outcomes. Subsequent analysis of the number of terminal decisions made at each observation stage has suggested a simpler model for the observer's behavior in this task. This model assumes that each decision is based upon the information obtained from the last observation, and that one alone, rather than upon an integration of the information gained from all of the preceding observations. This simpler model fits most of the data. That is to say, on a microscopic level, the data do not support the Wald model. [Supported by U. S. Air Force Contract No. AF19(604)-1728, monitored by Operational Applications Laboratory, Cambridge Research Center, D. C., and by U. S. Army (SC), U. S. Air Force (OSR, ARDC), and U. S. Navy (Office of Naval Research).]
Theory of Sound Propagation through Ducts Carrying High-Speed Flows
Authors: Powell Alan
Published: September 2005

The important problem of sound propagation in ducts carrying compressible subsonic flows is analyzed on the basis that the motion is one-dimensional. The multiple reflection method is extended to the case of sinusoidally varying pressure waves and a general integral formulation is developed. It is complicated because the total reflected wave, particularly, and the total transmitted wave must depend upon the time delay incurred by the propagation of infinitesimal reflections from along the length of the duct, and this depends upon the shape of the duct. It is shown how certain exact solutions can be obtained and these are given for the wave strengths composed of wavelets having undergone single, double and triple reflections. The frequency plays the strongest role in the reflected wave, and when the singly reflected wavelets dominate, it introduces a factor [sin(Ωχ)/Ωχ]e−iΩχ on the zero-frequency reflection, Ω being proportional to the frequency, and it and χ being dependent upon the change of Mach number at the ends of the duct. In contrast the transmitted wave is hardly affected by frequency. The analytical results apply to “almost conical” ducts, either convergent or divergent with the incident wave propagating with or against the flow direction. An approximate method, based upon the analytical results is demonstrated for ducts of other form.
Computer Program to Generate Acoustic Signals
Authors: Mathews Max V.
Published: September 2005

A new program is described for synthesizing complex acoustic signals on a digital computer. The acoustic output is obtained via a digital-to-analog converter and a loudspeaker operating on the numbers written on a magnetic tape by the computer. The technique is useful to synthesize music, to generate psychological stimuli, and in general to produce functions of time which must be controlled carefully by a sequence of parameters. The program operates as a compiler, first compiling an “orchestra” of instruments from generators which form basic building blocks. In this way very flexible specification of the instruments is achieved. The instruments are then “played” by a second computation producing notes under the control of a sequence of parameter cards. These cards typically specify characteristics such as duration, pitch, attack, and vibrato for each note. Many voices may be sounded simultaneously. The program has many potential applications, and the first three that have been tried are the generation of control signals for a speaking machine, a demonstration of tone quality as a function of attack and vibrato, and a short composition to show musical capabilities.
Vibrations of the Air Column and the Reed in the Clarinet
Authors: Backus John
Published: September 2005

A small condenser microphone inserted into the mouthpiece of a clarinet enables the vibrations of the air column to be observed. At low intensities the pressure variation in the mouthpiece is practically sinusoidal; at higher intensities harmonics increase in amplitude, but the fundamental still predominates. The sound pressure level inside the mouthpiece for loud tones reaches 166 db; this checks well with the pressure required for blowing the instrument. Simultaneous observations of mouthpiece pressure and reed displacement show that, during that part of its motion that it is not in contact with the mouthpiece, the reed follows quite faithfully the pressure variations. The reed itself is primarily stiffness controlled; however, the damping of the reed motion by the player's lip is a very important factor in the performance of the instrument. The influence of the reed on the pitch of the tone produced by the instrument will be discussed.
French Hornists' Scale of Blowing Effort
Authors: Voots Richard J. , Small Arnold M.
Published: September 2005

A scaling of speakers' vocal effort based on direct magnitude estimation has been reported recently (Lane, Catania, and Stevens). The authors have adopted similar methodology to scale the blowing effort used by French horn players. A total of thirteen players individually produced tones at random levels on the same musical pitch (concert C4). Players assigned a numerical value proportional to their blowing effort after each tone production. Output levels were recorded on a graphic level recorder. Tones were first produced normally in an anechoic room. The procedure was then repeated with the addition of high-level masking noise delivered by earphones during each tone production. Least-squares derived power functions appear to fit the data fairly well though a graphical analysis reveals deviations at low and high SPL. Exponents for the functions relating effort and SPL are about 1.1 for both normal and masked conditions. Players reported that, with masking, tones were still audible, but their loudness changed very little in spite of large changes in effort. The results seem to indicate that loudness plays a minor role in the French horn players' evaluation of blowing effort.
Slant of Hair Cells in the Cochlea
Authors: van Bergeijk Willem A. , Speeth Susan A.
Published: September 2005

The microphonic potentials of the lateral line organ in fish have twice the frequency of the simulating tone, unless the cupula is given a mechanical bias, in which case a second harmonic drops out of the microphonic, and a one-to-one correspondence between stimulating and microphonic frequencies is obtained (de Vries, Kuiper). In the mammalian cochlea, second harmonic-microphonics are not normally found. The outer hair cells slant toward the modiolus; this slant may be considered as a mechanical bias in the direction in which these cells are maximally sensitive (Békésy). If Kuiper's notions about the generation and cancellation of the second-harmonic component are accepted, it would follow that near the apical end of the cochlea a greater bias must exist to prevent second harmonics, than near the basal end, because the displacement amplitude in the apical portion is greater than in the basal turn. The outer hair cells, then, should show a greater lean toward the modiolus in the upper turns. Evidence for this exists in the literature (Fernandez), and we have been able to confirm it. The inner hair cells, however, are most sensitive in the tangential direction (Békésy). Although no evidence at all is available on the point, it is not unreasonable to suspect that the inner hair cells also have a mechanical bias preventing second harmonic formation. From the sign of Békésy's observations, the slant is judged to be toward the base of the cochlea. Anatomical evidence on this point will be presented and its implications discussed.
Models for Approximating Basilar Membrane Displacement. II: Effects of Middle-Ear Transmission
Authors: Flanagan James L.
Published: September 2005

At the last meeting of the Society I described three analytical models for approximating the displacement response of the basilar membrane to a known sound pressure at the eardrum. The models were valid for points lying roughly in the apical half of the membrane or for a frequency range up to about 1000 cps. It is over this range that the stapes displacement is essentially proportional to, and in phase with, the displacement of the eardrum. At higher frequencies the middle-ear transmission is less simple and influences membrane displacement in a more complex way. By use of data given by Békésy and by Zwislocki, a functional approximation to the middle ear transmission is derived. The approximation is used to take account of gross middle-ear effects and to extend the range of applicability of the original models to include points lying in the basal half of the membrane. Displacement responses, to an impulse of sound pressure applied at the eardrum, are calculated. Responses are compared for points in the basal half, in the apical half, and near the middle of the membrane. It is found that over the basal region the impulse response is dominated by middle-ear characteristics and is essentially constant in waveform. In the apical area the response is dependent upon place and is determined principally by the characteristics of the membrane along its length.
Some Factors Influencing the Acoustical Impedance of Guinea Pig Ear
Authors: Mundie J. Ryland , Henges David F.
Published: September 2005

A brief résumé will be given of our method of direct measurement of acoustic impedance of the ear in experimental animals with graphs of average impedance curves for guinea pigs. The acoustical impedance of the ear of a single animal is not fixed, but quite variable, particularly in the range of best auditory acuity between 2000 cps and 7000 cps. It appears possible that these impedance variations are controlled by the animal. Experiments will be cited showing the role of the double-chamber configuration of the middle-ear cavity in producing impedance changes. Results of some experiments demonstrating the possible effects of tensor tympani and stapedius muscles upon the acoustical impedance of the ear will be given.
Response of Two Degree-of-Freedom Systems to White Noise Base Excitation
Authors: Curtis Allen J. , Boykin Thomas R.
Published: September 2005

The response of a two degree-of-freedom system, consisting of a spring-mass-dashpot mounted on another spring-mass-dashpot, due to white noise motion of the base, is examined over the following ranges of system parameters: mass ratio, 0.01 ⩽ M ⩽ 1.0; damping factors, 0.01 ⩽ S1 ⩽ 0.10, 0.01 ⩽ S2 ⩽ 0.05; frequency ratio between uncoupled natural frequencies of each spring-mass-dashpot, 0.20 ⩽ W ⩽ 10.0. The response of many practical systems may be analyzed in terms of such systems. The lower mass may be visualized as a basic structure supporting equipment represented by the upper mass. Alternatively, the lower mass may be equipment, excited by the basic structure, with the upper mass representing chassis or components within. Analyses of such systems are often made on the assumption that the lower mass response is unaffected by the upper mass response, i.e., small mass ratio. The results presented explore the ranges of W and M over which such an approximation yields satisfactory results and indicate the magnitude of the errors in other ranges, particularly in the vicinity of W = 1.0, to which it may lead. The effectiveness of the upper mass as a “dynamic vibration absorber” for random excitation of the lower mass is demonstrated. The results for W = 1.0 are compared to previously published experimental results.
System for Measuring Complex Compression Moduli of Elastomers
Authors: Burgess John C.
Published: September 2005

A novel system is described with which the complex compression moduli of viscoelastic materials can be measured. The system consists of two duplicate sides each composed of a vibration exciter, viscoelastic sample, and connecting structure. The samples, connecting structures, and transducers are supported on rollers guided by smooth ways located between the two vibration exciters. An accelerometer is located between one vibration exciter and the nearest viscoelastic sample, and a force gage is placed between the two samples. The system is “balanced” by adjusting the amplitudes and phase angles of the exciter moving coil currents so that the force gage is stationary. The mechanical impedance of the viscoelastic sample, and hence its storage modulus and loss tangent, then can be calculated easily from the measured values of force and acceleration. The essential advantages of this system over other systems for measuring complex moduli are its low cost and the ease with which the measured quantities can be interpreted. Measurements have been made over the frequency range 25–750 cps for very soft elastomeric foams (storage moduli approximately 5 psi) and over the frequency range 200 3000 cps for a soft homogeneous rubber (about 25 durometer). Measured storage moduli for a given sample are estimated to be within ±5% and loss tangents within ±20% of the true values for that sample. This accuracy could be improved by increasing the sophistication (and hence cost) of the system. (Supported by Wright Air Development Division.)
Low-Frequency Spectrum of Deep Ocean Ambient Noise
Authors: Walkinshaw H. M.
Published: September 2005

From 1956 to the present, measurements of sea noise spectra have been made with experimental bottomed hydrophones at various locations near Bermuda and near one of the Bahama Islands. Depths ranged from 230 to 2600 fathoms at the Bahamas' site and from 220 to 1000 fathoms at Bermuda. Concurrent measurements of noise were made in half-octave bands, in fixed filter passbands 30 cps wide, and directly in a one-cycle band with a heterodyne analyzer. The frequency range investigated was in no case less than 10 to 400 cps or greater than 10 to 1600 cps. A factorial scheme of statistical analysis was followed for simultaneous investigation of the effects of receiver depth and time on spectrum levels. Noise at bottomed hydrophones in the deep ocean is dominated by shipping at frequencies below 200 cps and is strongly influenced by wind and weather at frequencies above 300 cps. Mean noise level has a winter maximum and a summer minimum, with an annual excursion of about 7 db. Seasonal changes in level are attributed to alterations in ray paths caused by changes in the thermal structure in the upper ocean layers. (This work was supported by the Bureau of Ships, Navy Department.)
Power Spectrum of “Surfseisms.”
Authors: Saenger R. Alfred
Published: September 2005

At the last meeting it was shown that a sequence of water waves breaking on the shore at periodic intervals generates a corresponding sequence of elastic pulses, or surfseisms, in the adjoining beach. Analysis of the amplitude distribution and power spectra of these signals suggests that surfseisms may be considered as samples of a quasi-stationary noise process. The power spectrum W(f; P) of this surfseism noise process is defined roughly as the power spectrum of the signal measured at some point P when the period of observation tends to infinity. It is the purpose of this paper to describe a theoretical derivation of W(f; P) in which the differential contribution ΔW(f; P) from each element of the “wave hammer” source is calculated from normal mode theory using a two-layered liquid model. With reasonable physical assumptions as to the nature of the source, the contributions ΔW(f; P) may be summed. The tuned character of the spectrum resulting from the “earth filter” is determined principally by the excitation functions of normal mode theory. The theoretical spectrum will be compared with experimental spectra obtained at Fire Island New York. (This work was supported by the Office of Naval Research.)
Controlled Temperature Dependence of Magnetostrictive Ferrites
Authors: Smith G. Sherwood , Mattiat Oskar
Published: September 2005

The properties of several magnetostrictive ferrites which are based on the nickel ferrite system have been investigated for temperature dependence in the range −80° to 120°C. The compositions studied contained the divalent ions of copper, cobalt, and iron substituted on a molar basis for an equal amount of nickel. Primary consideration was given to the temperature dependence of the mechanical resonant and antiresonant frequencies as well as the magnetomechanical coupling coefficients. The magnetic properties as determined from the magnetization curve and hysteresis loop also are considered. It was observed that the substitution of copper and cobalt for nickel in the base composition, NiO⋅Fe2O4, causes the temperature coefficients of the mechanical resonant and antiresonant frequencies to change from negative to positive. The reproducibility of properties is discussed in terms of composition, fabrication techniques, and final firing schedules. Parameters controlling the kinetics of the sintering reactions and the thermal reduction of Fe3+ to Fe2+ are discussed.
Spectrum and Contour Analysis of Ultrasonic Pulses for the Determination of Microstructure in Metals
Authors: Gericke Otto R.
Published: September 2005

The attenuation of ultrasonic energy in metals depends on the ratio of the ultrasonic wavelength to the grain diameter. Hence, microstructure can be determined by measuring the relative rate of energy loss in a specimen at various ultrasonic frequencies. Unfortunately, such measurements are extremely time consuming. A theoretical and experimental investigation carried out at Watertown Arsenal Laboratories indicates, however, that the desired relationship between ultrasonic attenuation and frequency can be obtained in a very quick manner if the test is carried out with ultrasonic pulses of rectangular envelope. Such pulses contain ultrasonic energy distributed over a fairly wide spectrum, and the influence of a frequency dependent energy loss can he determined either by spectrum or contour analysis of the attenuated ultrasonic signal.
Biochemical Effects of Ultrasound: Destruction of Tryptophan
Authors: Weissler Alfred
Published: September 2005

A sensitive fluorescence method has been used to study the process by which intense ultrasound (400 kcps) destroys tryptophan in dilute aqueous solution. Tryptophan is an essential amino-acid found in proteins and is closely related to plant growth hormones, to the vitamin niacin, and to the reserpine tranquillizer drugs. It emits a characteristic fluorescence at about 3600 A when excited at 2900 A. Serial recordings of the fluorescence spectrum after successive periods of ultrasonic treatment, made by means of an Aminco-Bowman spectrophotofluorometer, show that 95% of the tryptophan is destroyed after 24 min under the specific conditions used. The rate of destruction is somewhat slower in argon-saturated solution, and somewhat faster in oxygen-saturated solution, as compared with the air-saturated solution; in all three cases, the reactions rate conforms reasonably well to first-order chemical kinetics. As the tryptophan is destroyed, a substance with a new fluorescent peak at 4000 A is produced.
Detection of Heart Sounds at the Body Surface
Authors: Veneklasen Paul S.
Published: September 2005

Techniques are described for optimizing the use of a condenser microphone for hearing or recording heart sounds at the body surface. The object is to extend the frequency range of the sounds which can be detected and to permit recording and analysis of the maximum information which can be deduced from the sounds. The techniques involve reduction of noise threshold, relief of static pressure, efficient coupling to the body surface and acoustic and electrical equalization.
A 25-msec Mechanical Audio-Frequency Delay Line
Authors: Ashley George H.
Published: September 2005

A 25-msec delay line has been developed for the audio-frequency range from 300 to 3000 cps. The delay medium is a small-diameter wire under constant tension with a transverse wave velocity of about 50 m/sec. The input current passes down the wire and produces transverse velocities proportional to the magnetic field across the wire at each point. A single displacement pickup using light modulated by the transverse displacement of the wire is located at one end of the wire. The wire is sandwiched between two plates with variable spacing to provide an air viscosity termination at the other end of the delay line. Basically, the delay line has flat amplitude response since the pickup is located less than a quarter wavelength at 3000 cps from the end of the line, and at that point constant velocity input appears as a constant displacement output. The magnetic field across the wire at each point is determined by the lateral position of a small permanent magnet arranged so that the field can be varied linearly between plus or minus maximum strength. Complicated signals can be generated by adjusting the magnetic field across the wire at each point to correspond to the amplitude of the signal with time inversely proportional to distance from the pickup. (Lincoln Laboratory is operated with support from the U. S. Army, Navy, and Air Force.)
“TELATTACK”—a New Protection System for Detecting Attack-Generated “Noise” within the Walls of Vault-Type Structures
Authors: Lindsay Maxwell H. A.
Published: September 2005

The American District Telegraph Company for about a century has been supplying electric protective signaling services for the protection of life and property. For the latter half of that time it has employed sound detection systems for the detection of burglarious attack on bank and mercantile vaults. Modern building construction, coupled with industry development of more sophisticated cutting and penetrating tools, brought about by the war effort, has facilitated the burglar and made it necessary to design more effective and discriminating vault alarm systems. The ADT Company has pioneered in the development of a completely new transistorized sound detection system called “TELATTACK” which selectively detects burglarious attack noises and integrates them, yet rejects disturbances from unwanted sources of sound energy, such as street traffic and building noises. “TELATTACK” even makes it possible to apply protection reliably to structures where adjacent aircraft activity creates ambient sound levels in the order of 110 db.
Potential Dividing Function Generator for the Control of Speech Synthesis
Authors: Fourcin Adrian
Published: September 2005

An instrument is described which has been designed for use in conjunction with those speech synthesizers which can be controlled by independent, single-valued, synchronous functions of time. These controlling functions are drawn as a family of line graphs on a plastic sheet using an electrically conducting ink. The device is arranged so that each line acts as a potential dividing pick-off on the surface of an electrically conducting roller along the length of which is maintained a uniform potential gradient. Connections to outside apparatus are readily obtained, and the lines may be erased easily and drawn.
Eight-Parameter Speech Synthesis
Authors: Ingemann Frances
Published: September 2005

PAT, the Parametric Artificial Talking device (described in abstract G1 by Walter Lawrence) recently has been modified to synthesize speech using the following eight parameters: larynx frequency, larynx amplitude, three formants. frequency of the hiss filter, amplitude of hiss in the hiss filter, and amplitude of hiss in the second and third formants. By using these parameters speech has been synthesized both from spectrographic analysis and from minimal rules similar to those presented in earlier papers [Ingemann, J. Acoust Soc. Am. 29. 1255 (1957); A. M. Liberman, F. Ingemann, L. Lisker, P. Delattre, and F. S. Cooper, J. Acoust. Soc. Am. 31, 1490–1499 (1959)]. The rules originally designed for the Pattern Playback at Haskins Laboratories had to be somewhat modified and further simplified to remain within the eight parameters of PAT, but nevertheless intelligible speech has been produced. The types of modifications necessary will be discussed, and recordings of speech synthesized from analysis and by rule will be played.
Second and Third Formant Transitions in English Fricatives
Authors: Delattre Pierre C. , Liberman Alvin M. , Cooper Franklin S.
Published: September 2005

Two experimental situations were used to examine the role of formant transitions while minimizing that of friction noises as cues to the “place” identification of voiced fricatives. In the first experiments, using no friction at all, /v/ was distinguished from /ð/ by formant transitions alone; in the second, using a common “neutral” friction, /z/ was distinguished from /ȝ/ by formant transitions plus a neutral noise. F1 being fixed, F2 and F3 transitions were varied to determine the dimensions of maximal distinction between /v/ and /ð/ on one hand, /z/ and /ȝ/ on the other. If it can be assumed that F2 and F3 transitions are nearly the same in voiceless fricatives as in voiced ones, the results furnish information on transition cues for the eight English fricatives.
Perception of Speech-Like Sounds Characterized by a Rapidly Changing Resonant Frequency
Authors: Brady P. T.
Published: September 2005

A series of experiments concerned with the perception of sounds characterized by a moving resonance, i.e., one-formant sounds, has been performed. The stimuli are generated by exciting a tuned circuit of bandwidth 100 cps with a short train of pulses. The resonant frequency is varied linearly between two limits 500 cycles apart; increasing and decreasing frequency changes are investigated for terminal-frequency pairs 1000–1500 and 1500–2000 cps. By operation of a manual switch the pulse train is caused to excite a fixed resonant circuit, the frequency of which can be adjusted by a potentiometer. The subjects' task is to adjust the poteniometer until the signal produced by the fixed resonant circuit is most like that produced by the time-varying circuit. Results indicate a strong tendency for subjects to adjust the frequency of the fixed resonant circuit to the final frequency of the time-varying circuit. Judgments can be forced toward the starting frequency of the transition if an initial steady-state portion precedes the transition. [This work was supported in part by the U. S. Army (Signal Corps), the U. S. Air Force (Office of Scientific Research, Air Research and Development Command), and the U. S. Navy (Office of Naval Research); and in part by the National Science Foundation.]
Reduction of Signal-to-Noise Ratio Induced by Distortion in Speech Transmission Systems
Authors: Corliss Edith L. R. , Kobal Michael , Burghorn Susan E.
Published: September 2005

A study has been made of the influence of transient and intermodulation distortion on the transmission of speech occurring in the presence of a background noise having pronounced transient characteristics (cafeteria noise). This paper describes objective measurements of the power-time distribution in speech and noise, separately and in combination, for the sound coming from a sound source of high quality and for the sound coming from the earphones of hearing aids whose microphones were exposed to the sound source. The nature of the transmitted signal will be demonstrated. (This work was carried out under sponsorship of Veterans Administration.)
Precise Attenuation Comparisons in Liquids at Low Megacycle Frequencies
Authors: Turner William R.
Published: September 2005

The study of the abnormal attenuation produced in water by microbubble effects has required the development of instrumentation capable of detecting fractional decibel changes in attenuation over time periods of 100 hr or more. Other applications might include studies in which attenuation effects must be restricted to fractional decibel magnitudes in order to limit second-order effects, etc. The resolution and stability is achieved by a pulse system employing a quartz transducer and a reflector mounted in a cage that can be transferred readily between reference and test water bodies, A precise measurement of the relative attenuation is obtained by electronically switching the signal source between the transducer and a calibrated electrical attenuator and adjusting the attenuator to produce a signal that matches the echo. A passive hybrid network in the transducer line separates the echo from the source signal. Interface impedances are matched throughout the system to minimize errors produced by temperature changes on either the quartz or the liquid medium parameters. The source frequency is set at a fundamental or higher order resonant mode of the quartz plate, the present equipment operating at a single frequency near 5.0 Mc. Additions contemplated for the system in the near future include multiple frequency attenuation measurements in the 1- to 10-Mc range using a single quartz transducer at several resonance modes and provision for the simultaneous measurement of propagation velocity at each test frequency.
Infrasonic Pressure Waves from Tornadic Storms
Authors: Chrzanowski P. , Young J. M. , Marrett H. L.
Published: September 2005

Infrasonic atmospheric pressure waves with periods from 15 to 40 secs have been recorded at Washington, D. C., during times of severe storms in the central United States. Correlation of arrival times and directions with Weather Bureau reports of times and locations of tornadoes and funnels suggests that these waves are generated in the area of the severe storms. The observed pressure variations have a horizontal phase velocity across the receiving site of approximately the local speed of sound, and pressure amplitudes up to 1 d/cm2 have been observed. The characteristic properties of these traveling pressure waves are compared with the properties of waves from other natural sources.
Effect of a Reflecting Plane on the Radiation Impedance of a Multipole Sound Source
Authors: Bies David Alan
Published: September 2005

Expressions have been derived for the radiation impedances of a dipole and of a generalized quadrupole of arbitrary orientation and height above an infinite plane perfect reflector. It is shown that these expressions are generalizations of those derived previously by U. Ingard and G. L. Lamb, Jr. [J. Acoust. Soc. Am. 29, 743 (1957)]. Some general conclusions will be drawn about sound power radiated from distributions of multipole sources in the presence of an infinite plane perfect reflector.
Memory and the Psychophysical Function
Authors: Tanner Wilson P.
Published: September 2005

The form of the psychophysical function can be accounted for by assuming an imperfect memory. A theoretical exposition of the subject is presented, and three memory components are isolated experimentally. Those components are memory for (1) amplitude, (2) starting time and duration, and (3) frequency and phase. An equation is presented which leads to consistency between predictions of the signal detectability and empirical results for the form of the psychophysical function. (This work was sponsored by the U. S. Air Force Office of Scientific Research.)
Ideal Observer and Descriptive Models in Psychophysics
Authors: Clarke Frank R.
Published: September 2005

In order to understand the manner in which the concept of the ideal observer is used as a tool for building descriptive models of human behavior, it is necessary to differentiate two types of theory: (1) the theory of signal detectability with its mathematical model of the ideal receiver, and (2) a descriptive model of human detection performance which is being developed within the framework of the theory of signal detectability. This paper will atempt to make clear the differences between these two types of theory and to specify the role which each plays in the understanding of the performance of human observers in the detection of auditory signals. (This work was sponsored by the Operational Applications Laboratory, AFCCDD.)
Effects of a Background Standard on Detection of a Noise Signal
Authors: Green David M.
Published: September 2005

On each trial the observer hears two successive noise bursts: one I, the other I + ΔI. The observer's task is to select the interval containing the increment ΔI. The parameter of the experiment is the level of a continuous background noise B. The detectability. evaluated in terms of signal to noise ratio, is best when the background noise B is some 5 to 7 db greater than the level of I. The Weber fraction and the shape of the psychophysical function, using this special procedure, are also different from those obtained using standard procedures. It is suggested that at least part of this effect is related to temporal uncertainty about the observation interval. [This work was supported in part by the Operational Applications Laboratory, Air Force Cambridge Research Center, Bedford, Massachusetts; and in part by the U. S. Army (Signal Corps), the U. S. Air Force (Office of Scientific Research, Air Research and Development Command), and the U. S. Navy (Office of Naval Research).]