bluuebunny/crossref_metadata_2025 huggingface dataset:
Airborne Transportation Noise—Its Origin and Abatement
Authors: Powers John O.
Published: November 2005

The growth of airborne transportation has resulted in an increased awareness of the sounds associated with this form of travel. The noise generated by propeller-driven aircraft is given way to the sound of the exhaust jet, the compressor, and the fan whine. In addition, with the advent of supersonic flight, a new sound, the sonic boom, has been introduced to our acoustic environment. It is anticipated that airborne transportation will increase markedly in the coming years and as a result there could be a marked increase in the noise problem. The Federal Aviation Administration is attempting to minimize the acoustic impact of this increased air travel by attacking the problem on many fronts. The problem is initially defined through the mechanism of noise exposure forecasting. Methods are continually sought to reduce the noise at the source, to alter the sound transmission path, and to protect the community from the acoustic intrusion. Finally, procedures for national and international certification and regulation are being explored as a means of noise control.
Criteria for Control of Community Noise: a Candid Appraisal of Some Unresolved Questions as seen by One Acoustical Consultant
Authors: Blazier Warren E.
Published: November 2005

The acoustical consultant frequently finds himself on both sides of the problem in situations concerned with community noise. In either case, he must develop a criterion to evaluate the particular problem area—considering not only the physical control measures that are practical relative to the type source, but also the probable noise reduction requirements to achieve the subjective approval of the receiver. Each situation is likely to be complex regardless of whether the objective is to prevent a complaint or to correct one that already exists. There is a tendency on the part of municipal governments and other regulating agencies to establish noise limits on a basis which is too generalized or oversimplified to handle the broad range of individual situations encountered. An example is the ordinance of Coral Gables, Florida, which limits the noise level of residential air conditioning equipment installed outdoors. A comparison is made between this ordinance and noise data obtained on a large number of units operating, without complaint, in that city during the summer of 1966. General comments are made in connection with this survey which bear on the more fundamental problems faced in developing objective criteria for control of community noise.
Limitations on the Performance of Ultrasonic Delay Lines Using Vitreous Silica as the Delay Medium
Authors: Meitzler A. H.
Published: November 2005

The information storage capabilities of ultrasonic delay lines using vitreous silica (a term used to denote both fused quartz made from powdered crystalline quartz and fused silica made by oxidation of SiCl4 in an oxygen-hydrogen flame) are limited at low frequencies by the variation in the shear wave phase velocity and at high frequencies by the attenuation-vs-frequency dependence of vitreous silica. Recent experimental data [D. B. Fraser, J. T. Krause, and A. H. Meitzler, Applied Physics Letters (In preparation)] on the shear attenuation coefficient versus frequency dependence and the constancy of shear wave phase velocity are presented and combined with analytical models to estimate the maximum digital signal storage capabilities of ultrasonic delay lines using vitreous silica. In addition, other factors influencing performance limits, such as the temperature dependence of loss, the temperature coefficient of delay time, and the magnitude of the acoustoelastic effect in vitreous silica, are discussed.
The Effect of the Acoustic Fresnel Region of Transducers on Optical Measurements
Authors: Ingenito F. , Crandall A. J. , Cook Bill D.
Published: November 2005

The optical techniques for the investigation of ultrasonic waves have been limited by the lack of an exact mathematical expression relating the velocity amplitude at the source to the optical phase retardation experienced by the light passing through the sound beam. For low frequencies, (i.e., Raman Nath region) general expressions for the optical phase retardation for plane radiators of arbitrary geometry in a rigid plane baffle have been developed. Results for circular and rectangular sources are presented. [Work supported by the Office of Naval Research.]
Variable Angle Spectrometer for Brillouin Scattering (SBS)
Authors: O'Connor C. Leonard
Published: November 2005

An experimental system has been designed to study spontaneous Brillouin scattering from liquids with scattering angles that can vary continuously from 20° to 160°. This range of angles affords a method for velocity and absorption measurements to be made over a substantial portion of the dispersion region in most liquids, namely, from about 0.6 to 6.0 Gc/sec. The corresponding analyzing and detecting systems for the scattered radiation have been described earlier [J. Acoust. Soc. Am. 40, 663 (1966)]. The scattering cell is cylindrical and temperature controlled to 0.1C°. A variable cross arm, glass recticle, and autocollimation system in conjunction with an optical spectrometer is used to align and measure the scattering angle to at least±0.1°. Experimental results using a selection of organic liquids will be compared with data previously obtained by ultrasonic techniques.
Ultrasonic Method for Measuring the Thermal Expansion of Liquids
Authors: Pattison J. H. , Jarzynski J. , Davis C. M.
Published: November 2005

A new method of measuring the coefficient of thermal expansion of a liquid is described. First, the velocity of sound is measured over a precisely known fixed path length. Next, the time of flight of an ultrasonic pulse reflected from the free surface of the liquid is determined as a function of temperature. Using this data, the coefficient of thermal expansion is calculated. Preliminary measurements in mercury show that the accuracy of the accuracy of the above technique is ±1%. Furthermore, the combination of ultrasonic velocity and thermal expansion data permits calculation of the isothermal compressibility. [Work supported by a grant from the National Science Foundation.]
The Haas and/or Precedence Effects in Sound Localization
Authors: Gardner Mark B.
Published: November 2005

When two or more sound sources radiate identical complex signals, the listener tends to hear only a single image located at the nearer source, providing the maximum delay is less than about 50 msec. This phenomenon (together with other closely associated aspects) is generally referred to as the “precedence effect” or Haas effect.” Less frequently, the terms “Law of the First Wave Front,” “auditory suppression effect,” and “threshold of extinction” have also been used in describing certain of these characteristics. Perhaps the earliest investigator to leave a clear record of his appreciation of the single image aspect of the phenomenon was Joseph Henry who, in 1849, used the term “limit of perceptibility” in describing what he had observed. The present paper will give some of the historical background of the effect primarily from the standpoint of its investigation and its application in electro-acoustical systems. In addition, some recent data on the influence of multiple equal-energy sources on the accuracy of localizing the apparent single source will be given.
Time-Intensity Trade and the Lateralized Location
Authors: Asp Carl W.
Published: November 2005

Twenty-six male listeners completed the time—intensity trade and judged the lateralized location of interaural intensity differences from reference conditions of binaural loudness balance and binaural intensity balance. These signals of 150, 300, 600, and 1200 Hz were interrupted and had burst durations of 27, 20, 13, and 11 msec, respectively. The mean trading ratio increased as the frequency decreased and as the interaural intensity-difference increased. At lower frequencies, the mean ratio was larger when the trade was completed in a right-lateralized position. The mean judgments of lateralized location were 3.5 and 9.4 for right and left attenuation of 15 dB, respectively. The latter mean had a greater absolute difference from the midline number of 6.0. This indicated more displacement toward the right ear.
Lateralization of an Auditory Signal in Correlated Noise and in Uncorrelated Noise as a Function of Signal Frequency
Authors: Robinson Donald E. , Egan James P.
Published: November 2005

Listeners lateralized a monaural signal presented against a continuous background of perfectly correlated noise (NO) and of uncorrelated noise (NU). Measures of signal detection were also secured in separate tests. Psychometric functions (percent correct versus signal energy) were determined for each task. For a tonal signal of either low or high frequency, the listener requires only slightly greater signal energy (1–2 dB) in order to lateralize as well as he can detect when the noise is uncorrelated (NU). When the noise is perfectly correlated (NO), the slope of the psychometric function for lateralization depends upon signal frequency. With 250 cps, the slope of the function for lateralization is much smaller than that for detection. With 1000 cps, the function for lateralization is steeper than that for 250, but the slope is still less than that for the function for detection of 1000. With 2000 cps, the function has about the same slope as that for detection. [Research supported by U. S. Air Force Office of Scientific Research.]
Negative MLD's with Gated Sinewave Masking
Authors: Wightman Frederic L.
Published: November 2005

The detectability of S0 and Sπ signals, masked by a tone of the same frequency and duration, was measured as a function of the signal-masker phase. The signal and masker frequency was 250 Hz, and the duration 1/10 sec. In all conditions, Sπ signals were less detectable than S0 signals (a negative MLD), and this effect was largest (about 10 dB) with signal and musket in phase. Detection of S0 signals as a function of signal-masker phase closely follows the predictions of a simple energy detection model. The results with Sπ signals, however, are not consistent with any existing theory of binaural detection. In some general respects, the data suggest a mechanism similar to Durlack's equalization-cancellation mechanism. [Research supported in part by the National Institutes of Health, Public Health Service, U. S. Department of Health, Education and Welfare.]
Masking-Level Differences Determined with and without Interaural Disparities in Masker Intensity
Authors: McFadden Dennis
Published: November 2005

Psychometric functions were obtained for three listeners for the interaural conditions Nm-Sm and NO-Sπ using seven different noise spectrum levels. In addition, data were collected on the NO-Sπ condition with the spectrum level in one ear smaller than that in the other ear. In these NO′-Sπ′ conditions, the signal-to-noise ratio was kept equal in the two ears. The masking-level differences (MLD,s) for the NO-Sπ conditions declined gradually as the level of the noise was reduced, and for small spectrum levels were essentially the same as the MLD obtained when the musket was turned off. The MLD,s declined more rapidly for the NO′-Sπ′ conditions, but a small MLD was obtained even when the spectrum level in one ear was 60 dB smaller than that in the other car. For the Nm-Sm conditions, masking increased linearly with increases in spectrum level, but for NO-Sπ the relation was not linear. Signal: 400 cps, 250 reset. Masker: continuous, wide-band noise. Method: 2IFC. [Research supported in part by Air Force Office of Scientific Research and Public Health Service.]
Dichotic Loudness Summation for Pure Tones
Authors: Scharf Bertram
Published: November 2005

The over-all loudness of two equally loud tones, one presented to the left ear, the other to the right ear, was measured as a function of their frequency separation. The two tones were presented simultaneously for 700 msec and matched in loudness to a 2000-Hz binaural tone. Matches were made at 20, 50, and 80 dB above the threshold for the binaural tone. The geometric mean of the dichotic tones was 2000 Hz; seven frequency separations were used, from 100 Hz (one-third of a critical band) to 4530 Hz (12 critical bands). Results from six subjects indicated that the loudness of the two tones presented dichotically is independent of frequency separation. Moreover, at all three sensation levels dichotic loudness summation is the same quantitatively as binaural loudness summation. On the average, a dichotic or binaural sound is about as loud as a monaural tone that is 8 dB more intense. [Work supported by a grant from the U. S. Public Health Service, National Institute of Neurological Diseases and Blindness.]
Perception of Linguistic Boundaries
Authors: Hughes George W. , House Arthur S. , Rupf John A.
Published: November 2005

The necessity for segmentation in linguistic descriptions of an utterance has long been recognized. We have made a study of the perception of boundaries between phonemic segments of natural speech. Subjects were instructed to divide an utterance at the boundary between a consonant and vowel by causing the presentation (under phones) to switch from one ear to the other at a point in time corresponding to the CV or VC boundary. The means and variances of these subjective placements were measured and, intersubject variation was found to be greater than intrasubject variation, but both were large. Subjective boundaries seldom corresponded to prominent waveform features visible on a CRO. Subjective boundaries determined by switching were compared to subjective boundaries determined by listening to gated segments. [This work was supported in part by the Air Force Cambridge Research Laboratories under Contract.]
Psychoacoustic Implications of Inter-Species Communication
Authors: Truby Henry M. , Lilly John C.
Published: November 2005

As a corollary and prerequisite to the acoustic study of interspecies communication, consideration needs to be given to the psychoacoustic or psycholinguistic aspects of the problem. It should not, for example, be assumed that the communication systems (codes, “languages”) of alien species bear resemblance to those of Homo sapiens, and they are very likely unlike any of the currently active 5000 mutually exclusive human languages. It is difficult enough for a given human speaker with a single native language to comprehend any language much unlike his own, in spite of the sharing, on both the transmitting and the receiving side, of similar frequency and time domains, as is true for all human languages, and he needs more than a little convincing that a plethora of languages contemporary with his own are by nature so radically different in structural design and coding that he could apply none of his inherent linguistic instincts to their comprehension. This leaves no opportunity for fundamental pattern or system comparisons, i.e., perhaps there is no lexical inventorying, no verbal system, no connectives, or the like; perhaps the temporal sequence is complexly coded; perhaps that which is basic to human linguistics is incidental or nonexistent in the codal organization of alien species. Consider, for example, the bottlenose dolphin (Tursiops truncatus), who has three sonic-ultrasonic emitters, two of which can be linked in double or stereo phonation, and the third of which is used for sonar operation. This species apparently has alternating cerebral dominance, high rates of body locomotion and other muscular-operation speeds, and an acoustic frequency range approximately 10 times that of the human at both the transmitting and receiving terminals. These factors are indicative of a vocalization capability that is not only highly complex but fundamentally different from that of Homo sapiens. The complement of the dolphins' apparent patience with and affinity for human association adds to the challenge for expert professional psychoacoustic and psycholinguistic research on this particular species, as preparation for designing modi operandi suitable for treating any encounterable nonhuman codes.
Properties of the Instantaneous Frequency and its Application to Speech Classification
Authors: Hiramatsu K. , Raley D. K. , Wackerbarth R. , Coates C. L.
Published: November 2005

The instantaneous frequency, corresponding to the derivative of the phase function of the analytic signal, expressed in terms of the zeros of the function and its mean value, is formulated, and the properties of the instantaneous frequency will be illustrated using some typical examples. An expression for the instantaneous frequency in the complex frequency domain has been derived, and has the following properties: (1) When the spectral distribution is symmetric, the average value of the instantaneous frequency corresponds to the mean value of the distribution. (2) When asymmetric, the average value corresponds to the predominating region of the spectrum. Emphasizing or weighting the spectral distribution results in the predomination of frequencies that would not predominate under ordinary circumstances. The average value of the instantaneous frequency then corresponds to that region of the spectrum. The properties of these expressions for the instantaneous frequency will be applied to the classification of a limited number of connected speech sounds; i.e. zero, one, …, nine.
Speaker-Listener Dialect Error in Discrimination Testing
Authors: Koutstaal Cornelis W. , Hosack Martha
Published: November 2005

Articulation curves were obtained from a group of listeners who listened to speech discrimination-test words in their own dialect and a dialect different from their own. The speakers were from the General American dialect and the Southern American dialect regions. A male and a female speaker represented each dialect. The listeners were all from the General American dialect. The curves were derived from the mean values of 20 listeners for each of the nine sensation levels. Each listener responded to the test stimuli only at one sensation level, and to both dialects. The responses to the female speech sample showed a consistent difference in favor of the listener's own dialect. The responses to the male speech sample did not yield consistent differences in favor of either dialect. The difference between the responses to the male and the female speech sample is discussed.
Measurement of the Roughness of the Ocean Bottom
Authors: Clay C. S.
Published: November 2005

We would like to consider a description of the ocean floor that is particularly useful in ocean acoustics. The earth's visible surface is described by means of topographic maps and aerial photographs. To some extent, attempts to describe the ocean floor have followed this practice. However, the problem of constructing topographic maps is immense, and deep-sea photographs yield a postage-stamp view of the bottom. If we had long-range sonographs, most of our problem would be solved. (Side-looking sonars are a step in this direction.) Marine geologists have classified the ocean floor into physiographic provinces, and within each province the floor has similar properties. Experimental data have shown that in addition to the acoustic properties of the floor materials, the roughness of the interface is extremely important. In theoretical studies, roughness parameters such as the rms height of irregularities and their correlation functions over the illuminated area can be used to calculate the reflected and scattered signals. These are also measurable quantities. We urge those who study the acoustic properties of the bottom to report their results in standard physical units and statistical properties of the roughness. The development of an empirical bottom-roughness scale like the old sea-state scales and reflection-loss scales, etc., should be avoided. [Hudson Laboratories of Columbia University Informal Documentation No. 139. This work was supported by the U. S. Office of Naval Research.]
Backscattering of Sound from the Ocean Surface
Authors: Brown M. Vertner , Saenger R. Alfred
Published: November 2005

The backscattering of sound from the ocean surface has been measured in the frequency range 60 to 4000 Hz. Shots were fired at a depth of 3000 ft and “simultaneously” received on hydrophones directly above at 3000, 2000, 1000, and 100 ft. Concurrently surface roughness measurements were taken rising a gyrostabilized accelerometer buoy. As a general rule, all scattering coefficients at a given frequency fall on the same curve when plotted against (sinφi+sinφs). φt and φs are, respectively, the grazing angles of incidence and backscattering. (Hudson Laboratories of Columbia University Informal Documentation No. 136. Work supported by the U. S. Office of Naval Research.)
Possibility and Limitations in Sonoholography
Authors: Greguss P.
Published: November 2005

The geometric similarity of sound and light waves has simulated numerous attempts at visible sound images. Since 1964, efforts have been made to produce and to reconstruct holograms by ultrasonic waves. Sometimes there is a chance to get information from a hologram without wavefront reconstruction by using Moire fringes techniques. Wavefront reconstruction by ultrasonic waves promises a new way to overcome the difficulties issuing from the wavelength differences. Using a new acoustical-optical lens system, ultrasonoholograms can be obtained that can be treated as an ordinary laser hologram. Ultrasonoholography has its future not only in the nondestructive testing of materials, but also in ultrasonic diagnostics. Possibilities and limitations will be discussed.
Experimental Ultrasonic Image System for Underwater Use
Authors: Sackman G. L. , Barta A. F. , Well G. C. , Robinson K. G.
Published: November 2005

An underwater object is insonified by a 455-kHz pulse from a separate projector, and the reflected waves are focused onto a 9×9-element mosaic transducer fabricated from a single ceramic block, located at the focal plane of 90-cm-diam parabolic reflector. The transducer voltages are amplified by a set of 81 identical amplifiers with range gates, then rectified to charge storage capacitors. The capacitors are scanned in sequence by solid state switches driven by a microcircuit logic network, which also generates sweep voltages for the intensity modulated display. Resolution of 12° and tangential sensitivity of −110 dB re 1 W/cm2 have been measured, with interchannel crosstalk on the order of −20 dB. Digital-computer simulation of the system has emphasized the importance of aperture shading and proper reconstruction of the sampled image, in improving image quality. [This work was supported in part by the Office of Naval Research.]
Image Scanner Using Diode Switching
Authors: Suckling E. E. , Hendrickson J. R.
Published: November 2005

We have used in the past, as an ultrasonic image conversion system, a capacity probe tracing mechanically over the dry face of a crystal set in a tank wall. An image took several minutes to scan. The present system comprises 64 electrodes fixed in a line 3 in. long across a crystal. Diode switching brings in the electrodes consecutively. A scan of the line takes 1/300 sec. Experiments with a rotating sonic mirror indicate that a sonic image can be moved across the line of probes in 15 sec. The system then gives a video signal allowing the construction of a converted sonic picture comprising 4000 picture elements 5 times each second. Noise levels depend mainly on the switching diodes and since band widths can be quite restricted, are expected to be in the tens of microvolts. Illustrations of the video signal obtained from a parallel beam of 3 Mc/sec continuous wave ultrasound focused onto the array and from an image of two slots 116 in. wide and spaced 18 in. will be shown.
Evaluation of the Pohlman Technique—a Historical Note
Authors: Van Valkenburg H. E.
Published: November 2005

A brief report on a program sponsored by the Department of the Navy in the late 1940's to evaluate the Pohlman acoustic imaging technique for nondestructive testing. Reports were issued under the contract (NOas 8868), but no information was published. The results obtained, some very impressive, and the basic limitations encountered, are of current interest with respect to visualization technology. The system comprised a small water tank having a 20-in. beam path, transducer, sample holder, plastic lens, Pohlman window, and rf power source. Transducers were 1.0-in. diam quartz of 1 to 10 MHz frequency. The rf source was frequency swept to minimize standing waves. Best results were obtained on thin, flat, metal specimens; poorest on contoured samples. The technique appeared to be limited to the through-transmission method of inspection. Photographs of the equipment and of the images obtained on a variety of specimens will be shown.
AUTEC Acoustic Measurement Range
Authors: Alspaugh R. B.
Published: November 2005

The AUTEC Acoustic Range is a 5-by-20-mile facility for measuring and analyzing noise radiated from surface ships or submarines. The instrumentation system is discussed in terms of data acquisition and processing, preliminary analysis system, communications and navigation and underwater instrumentation. The bottom-moored hydrophone array will become operational by December 1967.
AUTEC Sonar Calibration Range
Authors: Herring F. P.
Published: November 2005

The AUTEC Sonal Calibration Range will be developed in three phases. Phase I will provide sonar hearing alignment and a range calibration. Phase II and Phase III will provide on-site sonar directivity pattern measurements in receiving and transmitting modes, source-level calibration, etc., for surface ships and submarines. This paper presents environmental and electroacoustical characteristics of the range.
Calibration of a Long-Base-Line Underwater Acoustic Tracking Range
Authors: McLennan Miles W.
Published: November 2005

In 1967, AC-DRL completed its Santa Cruz Acoustic Range Facility (acronymed SCARF) in the Santa Cruz Basin off Southern California. The range consists of four broad-band hydrophones set in a 6000-ft rhombus in 4000 ft of water. Cables run to signal processing electronics and a digital computer at a fixed site on Santa Cruz Island. The range is intended for precision multitarget underwater three-dimensional tracking and noise measurement. This paper describes the acoustic calibration experiment that determined the separation and depths of all hydrophones to less than a foot. A surface ship with fixed pinger was positioned at points in a 10 000-ft-square grid centering on the array, and 175 acoustic pings were emitted and recorded by the signal processors and computer. After the run, the computer did a least-squares fit of the hydrophone and pinger locations to the recorded transit times, using local tides and ray bending and transit time corrections form sound velocity profiles taken during the experiment. Using an edited set of 166 pings, the solution residual was 0.68 ft.
A Probabilistic Model for Acoustic Sound Ranging
Authors: Lee Robert P.
Published: November 2005

A probablistic model for acoustic sound ranging in a nonhomogeneous atmosphere has been developed. The model is based on a linear array of microphones. Error contour curves are presented that characterize the effects of of the nonhomogeneous atmosphere upon sound ranging results.
Sonar Transducer Calibration in a Controlled Pressure-Temperature Environment
Authors: Green C. E. , Roshon J. R.
Published: November 2005

It is known that both temperature and pressure affect the performance of most sonar transducers. A system has been installed at the Transdec facility of the Undersea Warfare Center, San Diego Division, so that a transducer can be subjected to controlled temperature from 40° to 90° F and/or pressure from 0 to 2000 psi during calibration. The transducer to be calibrated is mounted inside an acoustically transparent vessel 3 ft in diameter by 6 ft long. Water is circulated through the vessel and through a deck-mounted refrigerating-heating unit. A standard transducer known by other means to be independent of temperature and pressure shows no pattern or response deterioration when checked in the vessel. Examples will be presented that demonstrate the changes in performance in other transducer due to variations in temperature and pressure.
Acoustic Vestibular Stimulation in the Guinea Pig
Authors: Parker Donald E. , Reschke Millard
Published: November 2005

Observations of guinea pig eye movements associated with periodic (AC) and static (DC) pressure variations in the external auditory meatus are presented. Eye movements that are associated with normal vestibular stimulation were studied. These eye movements were determined by direct observation with a microscope and by electronystagmography. Stimulus intensities ranged up to 7 in. Hg. AC pressure variations were in the range of 0.25–10 Hz. DC pressure shifts were maintained for periods up to 15 sec. These stimuli produced three general types of eye movements: oscillatory eye movements, “counterrolling,” and nystagmus. Oscillatory eye movements at the same frequency as the stimulus, were observed in conjunction with AC stimuli at intensities of 2–3-in. Hg. Increasing stimulus intensity to approximately 5-in. Hg produced a movement analogous to that seen in normal counterrolling and, in some cases, nystagmus. DC pressure shifts in the range of 2–3-in. Hg produced counterrolling. With DC pressures of 3–4-in. Hg nystagmus was generally observed in conjunction with the counterrolling. These observations provide support for the hypothesis that acoustic stimuli may produce activity in vestibular receptors.
Echolocation: Resolution of Target Range by Bats
Authors: Simmons James A.
Published: November 2005

Echolocating bats (Eptesicus fuscus) were trained to discriminate between identical targets located at different distances from the bat. By means of a simultaneous discrimination procedure, the threshold for detection of differences in target range was determined. At an over-all range of 30 cm, the minimum detectable difference between the nearer and farther targets was 11 mm. The bats were blinded, and they emitted characteristic echolocation cries throughout the discrimination process. Three cues are available to the bats for detecting the difference in target range: the apparent size difference between the targets, the longer travel time for the echo from the farther target than for the nearer target, and the instantaneous frequency differences between the returning FM echoes slightly offset in time. Concurrent experiments indicate that Eptesicus probably measures target range by echo time delay.
Differential Effects of Cortical Lesions upon Various Types of Auditory Discriminations in the Monkey
Authors: Elliott D. N. , Frazier L. A.
Published: November 2005

Following preablation training on frequency, intensity, duration, and complex spectral difference discrimination tasks at three different frequencies, postablation performance was determined. Variations in the testing procedure were also introduced to determine the extent to which changes in discrimination performance reflected the specific nature of the discrimination task. For most animals, bilateral ablations of the primary auditory area produced amnesia, though occasionally this did not occur. (Presumably, the lack of even temporary amnesia reflects incomplete ablations, though final histopathological evaluations are not yet available.) For some animals, amnesia proved to be temporary in the sense that the discrimination tasks could be relearned (though they did not reappear spontaneously), while for others, discrimination performance was permanently affected. The various tasks can be ranked in terms of the probability that the lesion would produce either temporary or permanent amnesia, and these ranks are related to the initial ease of learning. However, since significant individual differences appeared in the ease of initial learning the various discrimination tasks, such a ranking is only of limited accuracy for the group of experimental animals as a whole. It was also found that varying the manner in which the discrimination tasks were structured often significantly altered the accuracy of postablation performance. It is clear that some type of explanative principle similar to Neff's theory of neural habituation for ablated animals is needed.
Amplitude of Auditory Evoked Vertex Potentials as a Function of Interstimulus Interval During Slow Repetitive Stimulation
Authors: Nelson David A. , Lassman Frank M.
Published: November 2005

Averaged auditory evoked potentials were recorded from human vertex in response to repetitive tone bursts presented at different interstimulus intervals. Interstimulus intervals were varied in discrete steps from 0.25 to 10 sec with a counterbalanced order between subjects. Tone bursts were 20-msec pulsed pure tones with 20-msec rise and decay times. Frequencies used were 500, 1000, and 2000 Hz. Although large variance exists in averaged evoked response amplitudes (N1−P2 peaks) within and between subjects, group means show N1−P2 amplitude to be an increasing function of interstimulus interval: as interstimulus intervals are changed from 0.25 sec to about 2.0 sec, response amplitude increases sharply to a partial asymptote between interstimulus intervals of 2.0 and 3.0 sec, then from about 3.0-sec through at least 10-sec interstimulus intervals, response amplitude continues to increase but the slope of the function is greatly reduced.
Short-Period Ocean-Bottom Seismograph—Development and Application
Authors: Guidroz Ralph R.
Published: November 2005

Natural and man-made seismic activity in ocean environments can be recorded in situ by self-contained ocean-bottom seismograph stations. Development of such operational capability was accomplished during 5 yr of testing and evaluation of three generations of ocean bottom systems. The first and second generation systems were attached by cable to a surface buoy and had less than 12-h recording capability. The present system is allowed to free-fall to operational depths of 4100 fathoms without the requirement of cable or attachment to the surface. The unit records three components of seismic activity and water pressure in the band 1–10 Hz on a 30-day tape recorder. Signals are amplified by low-frequency parametric amplifiers. A digital clock with a timing accuracy of 0.5 sec within a 30-day period is used for timing of data. Release of the system is accomplished by burning a fuse wire. Upon release, the sphere rises to the surface, where a beacon light and radio transmitter are activated to assist recovery operations. With existing technology other parameters can be measured; such as, salinity, temperature, ambient light, sound velocity, depth, gravity, magnetics, and water currents.
Geoacoustic Applications of Electro-Seismic Sources
Authors: Nash David M. , Barnes Thomas G.
Published: November 2005

A mobile high-energy source for electrically producing and controlling seismic pulses is described. Applications that employ one or more of these electroseismic sources include: (1) profiling of stratigraphy anomalies by complete insonification of the target, and (2) propagation investigations associated with a seismic network for detecting missile reentry. The high-frequency characteristics present in the source and the controllability of those characteristics is cited as a means, when used with appropriate sensors, of expanding the application to problems requiring greater resolution of detail.
Rôle of Digital Computers in Exploration Seismology
Authors: Judson Roger D. , Sherwood J. W. C.
Published: November 2005

In exploration, seismology surface sound sources and detectors are utilized to indicate variations in the elastic properties of the subsurface of the earth and from these infer the geological structure. It is helpful to pose the basic problem in a form that is common to most scientific investigations. One possesses data (time series from known seismic sources and detectors) plus a conceptual model (elastic wave propagation) with unknown parameters (the elastic variables as a function of space). The problem is to estimate the unknown parameters so as to get some best fit between the model and the data. At the present time, it seems impractical to attempt to solve this total problem directly. Instead, conceptual approximations are made that lead to a number of consecutive problems, each of which normally involves input data, some particular simple model and unknown parameters that need to be estimated before providing output data. A digital computer is a flexible device with which it is feasible to fit a variety of simple models to data, estimate parameters and transform input data to output data. This has caused a major revolution in the processing of seismic data during the last few years and has undoubtedly improved the over-all effectiveness of seismic exploration. Examples will be given of some of the processing.
Some Temporal Relationships between Speech and Hearing
Authors: McDill Jim D. , Mahaffey Robert B.
Published: November 2005

This study was designed to explore whether certain temporal patterns of speech are related to temporal aspects of hearing. The results of the study were obtained by correlating the tone-burst durations most accurately matched at each of three frequencies and the critical fusion frequency with three measures of speech. These measures were average phonation time, average pause time and the number of pauses per second. Twenty-one male and 21 female persons with normal hearing served as subjects. The results indicate that significant relationships exist between the average pause time and critical fusion frequency and tone-burst duration most accurately matched at 150 Hz. The same relationships existed for the average phonation time. These relationships would indicate a possible dependency of speech timing upon certain primitive aspects of temporal processing by the auditory system.
Discrimination of Vowel Spectrum in Sensorineural Hearing Impairment
Authors: Pickett J. M. , Martin Ellen S.
Published: November 2005

Measurements are reported comparing normal and impaired auditory discrimination for formant frequencies of synthetic vowels. Vowel spectra were shaped by two formant resonators with controllable center frequencies, F1 and F2. For discrimination measurements three vowels were presented on each trial. For two of the vowels, F1 and F2 were held constant. For the third vowel, F2 was set at a higher frequency. The task of the listener was to tell which one of the vowels was different from the other two. A programmer controlled the synthesizer so as to present a sequence of trials with downward adjustment of amount of F2 difference after each correct response and upward adjustment after each wrong response. Thus, over a sequence of trials the amount of F2 difference typically decreased from above the difference limen until oscillatory adjustments occurred above and below the limen. Results: frequency position and relative amplitude of F1 has a marked effect of the F2 discrimination limen. All groups show good F2 discrimination when the formants are separated by more than 1 oct. Some subjects demonstrated abnormally poor discrimination when F2 was 10 dB lower than F1, but improved when the amplitude difference was reduced. [Work supported by U. S. Public Health Service grant.]
Index of Criterion for Sentence Identification Tasks
Authors: Speaks Charles
Published: November 2005

At a previous meeting, the applicability of a statistical-decision model to a sentence identification task was described. The observer's task is to decide if a message belongs to a primary or secondary subset of messages. If primary, he is to decide which alternative primary message was presented. The observers generated ROC curves consistent with the model. A fortunate by product of the model is that in addition to describing performance by a criterion-free measure, it also is possible to specify, quantitatively, the criterion adopted by the observer for the task. The criterial index yields a value on a linear scale that ranges from −0.50 (extreme strict criterion) to +0.50 (extreme lax criterion). The theoretical distributions of the index for various values of d′ and empirical data from hearing-impaired persons will be presented.
Evaluation and Optimization of Nonlinear Quantization Characteristics in PCM Transmission of Speech
Authors: Fujisaki Hiroya , Kataoka Masanori
Published: November 2005

Nonlinear quantization has been introduced into PCM transmission of speech in order to reduce the quantization effects. Although signal-to-noise ratio has been conventionally adopted for the evaluation of such systems, assuming a negative exponential distribution for speech amplitude, there is little evidence for its validity. An evaluation theory is presented based on the information transmission rate of a quantized channel and approximating the temporal structure of speech by two distributions corresponding to voiced and unvoiced sounds. Articulation tests have been performed using both actual PCM systems and a flexible simulator and the results have been analyzed both in terms of the articulation score and the amount of information transmitted per syllable. The results indicate poor correlation between conventional calculations and articulation scores, and prove the validity of the proposed theory. Comparisons of known nonlinear characteristics lead to an optimum one that is somewhere between the logarithmic and the hyperbolic characteristics.
Study of Relations Among Terms Used for Subjective Evaluation of Telephone Transmission Quality
Authors: Duncanson J. P.
Published: November 2005

Many different rating scales have been used in the study of telephone transmission quality (for example: excellent, good, fair, poor). Twenty-one terms from five such scales were studied using two experimental techniques, paired comparisons and sorting by similarity of meaning. The first method yielded a scale value for each term along a single dimension of transmission quality. These values revealed that the five original rating scales vary widely in the range of quality spanned and in the evenness of spacing of the steps within the scale. The sorting method yielded a hierarchial clustering of the terms. It was found that the 21 terms can be sorted into five groups, the terms within a group being more or less equivalent in meaning. These two sets of data can be useful in constructing rating scales for particular applications by permitting (1) selection of terms to cover the desired range of quality, (2) selection of terms spaced approximately equally over the desired range, and (3) construction of two or more equivalent forms for use in repeated or reliability testing.
Shifts in Masking with Time
Authors: Bilger Robert C. , Melnick William
Published: November 2005

A time shift of remotely masked thresholds during the first 2 min after onset of noise has been contrasted to a presumed invariance of directly masked thresholds over time by earlier investigators. The time course of masking of a 500-Hz signal was determined for remote masking (noise from 2000–4000 Hz) and for direct masking (noise from 200–4000 Hz). Masking was determined for simultaneous onset of the noise and test signal and for delayed (2 min) onset of the tracking task. For half of the conditions, listeners varied level of the tone against a constant background noise, and in the other half they varied noise level to mask a constant level of pure tone. The results, in terms of signal-to-noise ratios, show that a downward shift in directly masked threshold (3 dB) occurred during the first 2 min of tracking. This shift in direct masking was influenced by both time of onset of the tracking task and by mode of control. The shift in remote masking with time (4.5 dB) in 2 min was independent of both onset and control.
Agreement in Detection: Observers and Electrical Model
Authors: Williams Paul I. , Jeffress Lloyd A.
Published: November 2005

At the Los Angeles meeting, Nichols reported that an electrical model (narrow filter-rectifier-envelope filter) predicted the responses of four observers in a single-interval detection experiment better than either a different electrical device (envelope-maximum detector) or the presence or absence of the signal. He suggested the desirability of employing multiple signal levels and a two-alternative, forced-choice method with a similar detector. The present paper reports such an experiment, with the first electrical model and three observers responding to the same stimuli. Seven signal levels were employed, and on some trials, noise alone occurred in both intervals. P(C) ranged from about 0.99 to chance (for noise-alone trials). The data show that the model predicts observers' behavior better than the presence or absence of the signal does, and better than one observer predicts another. When the three observers agreed in their responses (whether right or wrong) the model agreed with them on more than 81% of the trials. The weaker the signal the greater was the superiority of the model over the signal as predictor. (Noise: 100–3000 Hz, 50-dB spectral level. Signal: 500 Hz, 0.25 sec.) [Supported by the U. S. Naval ship Systems Command and the National Aeronautics and Space Administration.]
Signal Detection with a Fixed Sample of Masking Noise
Authors: Markowitz Joseph , Swets John A.
Published: November 2005

Detection of sinusoidal signals over trials containing precisely the same sample of background noise (“same-noise” condition) was compared with detection over trials in which the sample of noise varied from one trial to another (“different-noise” condition). All noise samples had a duration of 0.1 sec and a bandwidth of approximately 5000 cps. Differences among individual observers, with respect to the relative levels of detectability produced by the two conditions, were marked, and were consistent across several signal-to-noise levels, and across three psychophysical procedures. Preliminary results suggest that the individual differences in detection performance are correlated with differences in the individuals' abilities, assessed in separate tests, to discriminate among the various noise samples used. An observer able rather easily to distinguish different noise samples was substantially better at detecting the sinusoidal signal in the same-noise condition than in the different-noise condition; an observer almost completely unable to discriminate among Parlous noise samples was poorer at detecting sinusoids in the same-noise condition than in the different-noise condition. [This work was supported by the Human Performance Branch of the NASA Ames Research Center.]
Signal Uncertainty in the Multiple-Observation Detection Task
Authors: Swets John A. , Markowitz Joseph
Published: November 2005

Rates of growth of signal detectability, throughout trials containing several successive observation intervals, were compared for two conditions of uncertainty about signal frequency. The signal was a burst of either 700 or 1700 cps for 0.1 sec. The signal frequency was randomly varied within a trial (“simple-hypothesis” condition) or only between trials (“composite-hypothesis” condition). If, in the composite condition, the observer determined early in the trial which frequency was being presented, and used this knowledge to advantage in the later observation intervals of the trial, we should have obtained a rate of growth in detectability in the composite condition that was greater than the rate obtained in the simple condition, where no reduction of uncertainty was possible. In fact, there was no discernible difference in detectability in the two conditions, suggesting that the observers did observe and accumulate information separately at the two frequencies. Nonetheless, the observer's ability to recognize which of the two frequencies was present in the composite condition increased substantially over the first few observation intervals of a trial. [This work was supported by the Human Performance Branch of the NASA Ames Research Center.]