bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification and Discrimination of Phonemic Vowel Duration
Authors: Bastian Jarvis , Abramson Arthur S.
Published: September 2005

Hunter College, New York, New York Experimental findings on the perception of certain consonants are consistent with an articulatory feedback hypothesis that relates discontinuity of articulation to the discontinuous perception of what would be an acoustic continuum. An extension to a phonemic distinction in which an articulatory and an acoustic continuum are possible would lead one to expect no discrimination peaks in the perception. This extension of the hypothesis has been tested on the feature of relative vowel duration, by which words can be minimally distinguished in the Thai language. Fourteen length variants generated by tape cutting from the long member of a minimal pair of words were identified phonemically by Thai subjects with a definite but not sharp phoneme boundary. In forced-choice discrimination tests, the Thai speakers showed no discrimination peak at the phoneme boundary, and, in mimicry experiments, they tracked the stimuli continuously, equally well at the phoneme boundary and within the phoneme category. These results contribute to the validation of the hypothesis. For the purpose of making a cross-language comparison, American subjects were also tested. In their mimicry and discrimination of the stimuli, they behaved as the Thai did. In the identification test, the American subjects labeled the stimuli as “short” or “long” (since no phoneme boundary was relevant), but showed a wider range of indeterminacy and greater context effects than the Thai.
Experimental Investigation of Jet Noise Generated by Cold Air Flow through a Wide Variety of Small Nozzles
Authors: Sperry William C.
Published: September 2005

Over-all sound-pressure levels were measured in an anechoic room for 20 different nozzle configurations, including converging, converging-diverging, slot, and annular types, the latter with and without center-core flow. The results are examined in terms of over-all acoustic power vs mass flow, and they are compared with various eighth-power relations. The acoustic performance of most nozzles was similar in the subsonic region. Howere, certain annular-type nozzles exhibited a marked superiority in the supersonic region. (This work was supported by Propulsion Laboratory, Aeronautical Systems Division.)
Aeroacoustic Coupling for Jet-Noise Suppressors
Authors: Morgan James A. , Oran Frederic M.
Published: September 2005

The audible broad-band noise generated by the discharge of high-velocity gases into a relatively static medium can be reduced by effectively changing the discharge area to a multiplicity of smaller jets. Therefore, the normally audible noise is partially transformed into the inaudible range. The MULTI-JET, essentially a perforated colander, utilizes this principle. To obtain satisfactory performance with this type of diffuser, it has been found necessary to match accurately the diameter of the colander to that of the jet-exhaust nozzle. This matching involves a careful correlation between the diameter of the engine nozzle and the diameter of the colander together with the proper spacing between the nozzle and the colander entrance so that a close coupling is realized. Field tests have proven that maximum performance is obtained when the diameter of the colander is equal to or slightly larger than the diameter of the jet. In view of the many engine configurations presently operational and in view of continuous changing engine types, maximum utilization of a single colander cannot be realized. In addition to degradation in acoustic performance, mismatching also engenders other problems. In the case of an oversized colander, “boom” phenomena have been observed. In addition, backflow is created. This backflow causes temperature rise that complicates engine calibration and may even damage engine accessories. Aside from the problem of mismatching, present colander-type suppressors have limited use. During afterburner operation, exhaust temperatures reach the neighborhood of 3000°F. Therefore, it has been the practice to employ the MULTi-JETS only during the so-called military operation of the engines. This limitation has persisted, notwithstanding the attempted uses of a liquid coolant, since severe thermal shocks generated by application of coolant produce rapid suppressor deterioration. The aeroacoustic-flow diffuser evolved from a series of design and through numerous field tests has resolved the three major problems: acoustic performance, aerodynamic capacity, and structural durability. Field experience and test data relevant to the final design of a water-cooled aeroacoustic diffuser are discussed.
Combination of Noise and Pure-Tone Masking
Authors: Green David M.
Published: September 2005

Consider a pulsed sinusoid of 110-sec duration partially masked by white noise. It is well known that the level of signal must be varied linearly with the level of the noise to maintain some constant degree of masking. That is, the degree of masking is constant if the signal-to-noise ratio is constant. A similar relationship holds for a pulsed tone masked by a continuous sinusoid of the same frequency. Suppose, in separate experiments, the level of noise and level of the continuous sinusoid are adjusted so that each has equal masking effectiveness on a signal of some given level. If now the noise and sine-wave masker are combined, how much must the level of the signal be increased in order to achieve the same level of masking effectiveness as before? Rather than 3 db or some lesser number, the increase appears to be somewhere between 6 and 8 db. Other experiments related to this phenomena are discussed. [This work was supported by the U. S. Army Signal Corps, the U. S. Air Force (Operational Applications Laboratory and the Office of Scientific Research), the Office of Naval Research, and the National Science Foundation.]
Auditory Adaptation
Authors: Harbert Fred , Young I. M.
Published: September 2005

An interpretation of Békésy audiograms is presented indicating that small amplitude of excursions is due to abnormal rapid adaptation and not to a phenomenon of recruitment. The slow form of adaptation is illustrated by threshold drift of fixed-frequency tracings. The level of Békésy threshold audiograms on cases showing abnormal adaptation is shown to be dependent on the length of off-time when the stimulus is presented with various on-off ratios. Auditory flutter is also dependent on a minimum off-period. It is suggested that these phenomena are related to recovery from adaptation. Since cochlear microphonics (presumably a hair-cell phenomenon) show no reduction over time at all nondamaging intensities, adaptation is considered a ganglion-cell phenomenon. It is further postulated that adaptation in nerve lesions may be normal as in many cases of presbycusis. In such cases, the majority of nerve cells are normal. When there is significant partial injury, abnormal adaptation may be expected. Dendrite injury may be associated with abnormal rapid adaptation and axone injury to abnormal slow type.
Temperature and Amplitude Dependence of Acoustic Absorption in Tissue
Authors: Dunn Floyd
Published: September 2005

The acoustic-intensity-absorption coefficient of tissue of the central nervous system has been determined at the sound frequency of 1 Mc/sec in the temperature range from 2 to 28°C at incident sound intensities in the approximate range from 5 to 200 w/cm2. The absorption coefficient exhibits an increase with increasing temperature and no variation with acoustic intensity. (This research was supported by contract USPH B-1017, Institute of Neurological Diseases and Blindness, National Institutes of Health, Public Health Service, U. S. Department of Health, Education, and Welfare.)
Factor Analysis of Tests for Listening in Noise
Authors: Harris J. Donald , Cohen Burton H.
Published: September 2005

A battery of 21 contact-detection tests was prepared consisting of a variety of signals immersed in one of three types of background noise. Signals were pure-tone pulses, filtered clicks, speech, and several other complex sounds. Backgrounds were either white noise, a frequency-modulated noise band, or an interrupted noise. The fundamental question is whether performance in handling tasks involving unfavorable S/N ratios is an unitary trait or whether several different (though perhaps related) abilities are involved. Two groups of young men, of average or better intelligence, were given the battery: a group of 72 given special motivation and more prolonged testing, and a group of 700 given more-routine treatment. Four factors emerge from a Thurstone centroid treatment: an ability to detect complex noises, an ability to understand masked speech, an ability to detect tone pulses in a noise, and an ability to detect clicks in an interrupted noise. Interpretations of these factors are offered. Evidently, the area of contact detection is factorially complex; parameters involved in any particular experimental situation may not necessarily be involved in the same way in other situations.
A Study of /w/ and /y/ in American English
Authors: Lehiste Ilse
Published: September 2005

The study reported in this paper deals with the acoustic manifestations of various allophones of /w/ and /y/ in American English. Occurrences of initial /w/ and /y/, followed by different syllable nuclei, are described. The manifestations of initial /w/ and /y/ are compared with the syllable nuclei /u/, /ᴜ/, /i/, and /ɪ/. In addition, the second components of the glides /eɪ/ and /oᴜ/, and of the diphthongs /ɑᴜ/, /ɑɪ/, and /ɔɪ/ are considered. The characteristics of initial /w/ and /y/ include both steady state cues and transitional cues. The second component of the diphthongs /ɑɪ/ and /ɔɪ/ falls approximately in the range of /ɪ/ as a syllable nucleus; the second component of the diphthong /ɑᴜ/ has no obvious overlap with the ranges of either /u/ or /ᴜ/. No immediate identification of initial /w/ and /y/ with the second components of glides or diphthongs appears possible.
Vibration Reduction in Plates with Joints and Stiffening Ribs
Authors: Pallett David S.
Published: September 2005

Previous studies conducted in this laboratory on the vibrations of plates with joints were concerned primarily with rigid bar joints presenting essentially a one-dimensional constraint. Photographs of this system's nodal patterns clearly demonstrate transmission of those modes having nodal lines parallel to the joint, in agreement with theory, while for more complex patterns only the component parallel to the joint is transmitted. Present work centers about an investigation of multiple-joint and joint-stiffener rib combinations that approximate a two-dimensional constraint. Measurements made of the velocity distribution of freely suspended plates with such joints are discussed.
Correlation Measurements of Surface-Reflected Acoustic Signals for Several Sea States
Authors: Olson John R.
Published: September 2005

A study was made at various sea-state conditions of the coherence of an acoustic signal that has undergone one surface reflection. The source and receivers were bottom-mounted in deep water near Bermuda. Two types of correlation measurements were made: (1) crosscorrelation of a surface-reflected signal received at two hydrophones 500 ft apart, and (2) crosscorrelation of a surface-reflected signal with a replica of the transmitted signal. The signal consisted of random noise for (1) and pseudorandom noise for (2). In both cases, the signal was limited to a 300-cps band centered at 750 cps. Results indicate that the coherence decreases with increasing sea state in a linear manner. Normalized crosscorrelation coefficients obtained from the two hydrophones decrease from about 0.9 for a waveheight of 5 ft to 0.5 for a waveheight of 20 ft. Values obtained for the single-hydrophone output and replica fall off at a much slower rate. [Work supported by the Bureau of Ships, U. S. Navy.]
Measurement and Analysis of Underwater Acoustic Backscattering from a Model Ocean Surface
Authors: LeBlanc Lester R. , Hill R. F.
Published: September 2005

A 12×4×4-ft model tank is utilized to measure the underwater acoustic backscatter from a wind-driven surface. A single transducer is used to transmit and receive a 0.1-msec pulse at a repetition rate of 1000 pulses/sec. The carrier frequency is varied in the range from 200 kc/sec to 2 Mc/sec, which gives an acoustic wavelength/root-mean-square water-waveheight ratio from 0.2 to 2.0. Observations of the relative energy return are made as a function of the incident angle for a fixed path length. A mathematical model is hypothesized that predicts the backscattered energy as a function of incident angle, transducer-beam pattern, frequency, and surface statistics. Curves are presented that compare the observed data with the mathematical model. [This investigation supported by the Acoustics Program, U. S. Office of Naval Research, and the U. S. Naval Underwater Ordnance Station, Newport, R. I.]
Acoustic Phonetic Transcription of Written English
Authors: Bhimani B. V. , Dolby J. L. , Resnikoff H. L.
Published: September 2005

The function that maps the words of written English onto the corresponding words of spoken English is described. The simplest hypothesis is that this function F, defined on the symbols forming the letters of the alphabet, maps each letter onto a sound, and maps the sequence of letters L1L2 as F(L1L2) = F(L1)F(L2). This hypothesis is false, since F is not always well-defined in the sense that its values are not always unique and the equation does not always persist. On the basis of an exhaustive dictionary search, we have shown that: it is possible to define F in a context-dependent manner such that its restriction to consonant strings is uniquely defined; with this new definition, the equation holds for consonant strings of the gramatically homogeneous one-vowel string words of written English; the consonant strings in these words coincide with those uninfluenced by the rules of euphonic combination. [B. V. Bhimani, J. Acoust. Soc. Am. 35, 1912 (A) (1963); J. L. Dolby and H. L. Resnikoff, Language 40, No. 2, 167–196 (1964).] [Work supported by Lockheed Independent Research.]
Phoneme Proportion Constancy in English
Authors: Schultz M. C. , Bogardus L. J.
Published: September 2005

It was hypothesized that results would differ for phoneme proportions taken from markedly different sources—for example: written versus oral material; highly familiar versus less familiar material; polysyllabic versus monosyllabic words; etc. Counts were made from phonemic transcriptions, using General American as a pronunciation guide, of the following samples: 500 most frequently occurring words of Thorndike-Lorge; 500 words, each occurring less than once per million; all monosyllables from the first 500; a random sample of 100 of the first 500. These counts, in addition to the Dewey phoneme-frequency count, and Tobias' transcription of the French, Carter, and Koenig data were evaluated by product-moment correlations for raw data and coefficients of concordance for ranked data. Both types of indices yielded comparable magnitudes, varying between 0.85 and 0.97. The phoneme counts were correlated with acoustic and psychophysical measures from several sources but no simple relations were forthcoming. [This investigation supported by the National Institute of Neurological Disease and Blindness, National Institutes of Health, U. S. Department of Health, Education, and Welfare, grant NB-03162.]
Elastic Properties of Solids at High Pressure and Temperature
Authors: Hughes Darrell S.
Published: September 2005

The design for a 30-kbar pressure apparatus is presented. A sample holder containing a heater winding was designed to permit the measurement of the dilatational and the rotational wave velocities in solids. The experimental procedure for the apparatus is discussed. Dilatational and rotational wave velocities were measured, by the single-pulse method, as the pressure and temperature were varied at pressures from 4.5 to 18 kbar and a temperature range from 22° to 1000°C. Samples investigated were Armco iron, 0.7% carbon steel, normal uranium, Burma jadeite, and Labradorite. A computer program was written to adjust the velocities for the change in the sample's dimensions due to the change in temperature and the change in pressure. The program calculates the elastic moduli of the sample and fits a linear or quadratic curve to the points (linear or quadratic in pressure and temperature).
Propagation of Low-Frequency Sound near the Earth's Surface
Authors: Tedrick Richard N.
Published: September 2005

The output of a high-intensity directional noise source was investigated over transmission paths of nearly two miles in length. Data are presented showing the quantitative effects of refraction upon the measured sound-pressure levels. The variations from classical inverse-square-law propagation are examined in depth as a function of the velocity of sound gradient with altitude. More-exact values of the attenuation due to atmospheric effects are given for discrete frequencies in the 40- through 160-cps band. The long path length was sufficient to provide some measure of the complex effects of relative humidity on low-frequency propagation.
Receiver-Operating Characteristics by Rating Scale for Antiphasic Stimulation
Authors: Watson Charles S. , Rilling Mark E. , Bourbon Walter T.
Published: September 2005

This paper describes the replication by the same authors of an experiment that was reported earlier [J. Acoust. Soc. Am. 36, 283–288 (1964)]. The replication differs from the original experiment in employing an antiphasic stimulus condition N0Sπ. The equipment, a mechanical, rating-scale device, was the same as used formerly, and with the same procedure. The new ROC curves are strikingly different from those obtained earlier for the same subjects under the diotic stimulus condition N0S0, and imply substantially different noise and noise-plus-signal distributions. The rating-scale procedure appears to be a useful tool discovering the nature of the underlying distributions for noise and noise plus signal. [Work supported by USN Bureau of Ships contract NObsr-72627 and under a grant from the National Aeronautics and Space Administration R-129 through ONR contract 3579(04).]
Reflectivity of Deep Sedimentary Bottoms
Authors: Lallement Bruno , Stangerup Paul
Published: September 2005

A model for bottom-reflectivity loss has been developed in connection with bottom-reflection experiments made with explosive sources in the Mediterranean Sea. The bottom is considered as a fluid medium with attenuation losses. This model has been found to be a good approximation of variations of the reflection coefficient versus frequency and angle of incidence on the sea floor in the case of flat bottoms. Experimental results have been obtained for frequencies varying from 70 cps to 8 kc/sec and angles of incidence from 20° to 85°. Examples of these results are given, including computation of critical angle, of ratios of densities and velocities in the different media, and of attenuation coefficient, and evidence of two sediment layers in a particular case. An attenuation law has been derived from the frequency dependence of the reflection coefficient. Pulse shapes of the first and the second bottom bounces have been related to theoretical phase shift. It is felt that this model is useful to predict bottom reflectivity and pulse distortion in smooth deep bottoms and will have to be improved for rough areas.
New Technique for the Investigation of Ocean-Bottom Acoustic Structure
Authors: Fox George R.
Published: September 2005

A technique is described for investigating the acoustic structure of the ocean bottom by spectral analysis of signals radiated from a broad-band sound source at the surface and received at hydrophones on or near the bottom. Spectrograms made of the received signals show a periodic structure, due to the interference between direct and bottom-reflected sound. The spacing in frequency between maxima depends on the sound speed, arrival angle, and distance between the receiver and the plane of reflection. Spectrograms recorded in an area south of Bermuda exhibit a complex interference pattern apparently associated with reflections from several sedimentary layers. To obtain quantitative measurements of the characteristics of the layers, the output of a sound spectrograph, making successive sweeps through a given range of frequencies, was itself analyzed on a second spectrograph. In this spectrogram, which displays the so-called cepstrum, each maximum corresponds to a bottom-layer reflection. Examples are shown of both types of records, along with their interpretations. [Work supported by the Bureau of Ships, U. S. Navy.]
Periodic Variations of the Underwater Ambient-Noise Level of Biological Origin
Authors: Clapp Gerald A.
Published: September 2005

Two distinct periodic variations in the underwater noise level have been observed in coastal waters off San Diego. The first has been previously reported and appears diurnally before sunset, reaches maximum amplitude just after sunset, and then fades away within 3 h. This variation is observed in the 100- to 1000-cps band and raises the sound-pressure level 5–20 dB above the normal background, with maximum duration and intensity occurring in the Summer months. This effect is occasionally noted at sunrise, though with lower amplitude than at local sunset. The second periodic variation has a period of 25–40 sec and is observed only at night in the late Spring and Summer months. Its amplitude is commonly from 3 to 6 dB but maximums of 16 dB have been noted. It is observed above the background in the 300- to 800-cps band, with peak amplitude occurring at about 450 cps. Two members of the croaker family—spotfin, Roncador stearnsi, and yellowfin, Umbrina roncador—are in part responsible for the periodic variations.
Temperature- and Wind-Dependent Ambient Noise under Midwinter Pack Ice
Authors: Milne A. R. , Ganton J. H.
Published: September 2005

Underwater ambient-noise spectra are described for data acquired during early February 1964, west of Ellef Ringnes Island in the Canadian Arctic Archipelago. Weather conditions enabled a separation of temperature- and wind-dependent contributions to the underwater noise to be made. Declining air temperatures caused tensile cracks to occur at the surface of the sea ice. This cracking produced highly impulsive non-Gaussian noise. With increasing ice temperatures, cracking activity ceases. Then wind-dependent Gaussian noise is observable with an entirely different spectrum. The wind noise, between 100 cps and 10 kc/sec at least, appears to be frequency-independent and increases in level in the order of 16 dB per doubled wind speed.
Application of Digital-Computer Techniques to the Study of the Impact Dynamics of Lunar-Landing Vehicles
Authors: Walton W. C. , Durling B. J. , Leonard H. W.
Published: September 2005

The Langley Research Center is currently conducting a combined analytical and experimental study of the dynamics of lunar-landing vehicles. This paper deals with the analytical phase of this work. It outlines the general mathematical model and the idealizations of the structure and landing surface employed to simplify derivation of the equations of motion in 3-dimensional space. Special attention is given to idealization of shock absorbers and interactions between footpads and the surface. A digital-computer program for solution of the equations of motion is discussed. Computed motion-time histories are presented that show shock-absorber action and vehicle accelerations for a realistic lunar-landing vehicle during the landing process from touchdown to rest.
Vibration and Acoustics Facilities at Manned Spacecraft Center
Authors: Griffith G. , Wren R.
Published: September 2005

Vibration tests in support of manned space flight have been conducted by MSC since the origin of the Manned Spacecraft Center; this, of course, is ever increasing in both magnitude and scope and now embraces the field of acoustic testing. This paper discusses the sources of dynamic excitation in flight, whether vibration or acoustics, to the spacecraft or its occupants, and relates the resulting forces to the need for certain test facilities. Such facilities, either in existence or currently in construction, are described with regard to their physical make and environmental-simulation potential and their use is illustrated by descriptive examples, experimental programs, test procedures, and technical results.
Two-Signal Paradigm: Whole-Nerve Action-Potential Responses
Authors: Teas Donald C.
Published: September 2005

Action-potential responses were studied for different signal strengths, frequency combinations, and time separations between two brief tone pips. Control and experimental responses were interleaved to provide simultaneously averaged responses to experimental and control conditions. The ratio experimental/control (peak-magnitude) varied as a function of time separation (2, 4, 6, 8, 10 msec), frequency combination (6, 2 kc/sec), and signal strength (0, 6, 12, 18, 24 dB re visual detection on the single traces). For the like-signals case, the ratio E/C increased as the strength of the test signal increased; for the unlike signals, where high preceded low, the ratio E/C decreased as strength of the test signal increased. For time separations of 2 msec, both like and unlike signals produce E/C > 1.0. However, for the high-to-low frequency combination, E/C can exceed 1.0 at some time separations.
Normal Cytoarchitecture of Corti's Organ by Phase-Contrast Microscopy
Authors: Hawkins Joseph E. , Beger Valerie
Published: September 2005

Surface preparations of the organ of Corti, dissected from cochleas fixed and stained with OsO4, or from fresh specimens, can be examined immediately by phase-contrast microscopy, according to the method of Engström et al. [Acta Oto-Laryngol. Suppl. 188, 92–99 (1964)] without the delays and distortions occasioned by decalcification and celloidin embedding. Since both the cytoarchitectural pattern and the condition of individual cells throughout the entire length of Corti's organ can be studied directly and in detail, the method provides information that cannot be obtained from the familiar stained serial sections of temporal bones. Photomicrographs are presented to illustrate the method of preparation and the appearance of the organ of Corti, the stria vascularis, and the basilar, tectorial, and Reissner membranes of the normal guinea pig.
Comparison of the Effects of Cortitoxic Antibiotics and Intense Sound on Cochlear Potentials in the Guinea Pig
Authors: Aran Jean-Marie , Hawkins Joseph E.
Published: September 2005

Treatment with cortitoxic antibiotics, such as kanamycin, and exposure to intense sound have both been shown to bring about selective degeneration of the outer hair cells of Corti's organ. A common factor, such as interference with oxidative metabolism, might be inferred. The cochlear potentials, however, are differently affected by the two types of destructive treatment. In guinea pigs exposed to single tones of 500–4000 cps, at sound-pressure levels of 140–150 dB, the neural (AP) component of the cochlear potentials was depressed before the microphonics (CM). After kanamycin treatment (e.g., 200 mg/kg/day subcutaneously for 20 days), AP showed little or no change, but CM was severely depressed. Measurements of the potentials recorded with round-window, apical, and intracochlear electrodes suggest that these differential effects depend upon different sites of action along the organ of Corti and different modes of action upon the hair cells.
“Cortical Conditioning” in Auditory Evaluation
Authors: Pollock K. C.
Published: September 2005

The use of evoked cortical potentials as an indicator of auditory acuity is limited by the small number of stimulations possible before the acoustic signal no longer produces this response. The present study employed a form of “conditioning” in order to prolong responsiveness; a test tone was temporally associated with light flashes until the tone came to produce an EEG response in anticipation of the photic stimulus. Auditory thresholds obtained with this electrocortical anticipatory response were comparable to those given voluntarily by 23 of 24 normal-hearing young adults. Pure-tone frequencies of 500, 1000, and 2000 cps were used in a counterbalanced design to examine transfer of the EEG response between frequencies; no difference in transfer was found. The electrocortical anticipatory response is viewed as a promising tool in assessing the auditory capacity of persons who are unable or unwilling to respond voluntarily in current audiological procedures. This technique is also considered an indicator of the functional integrity of the higher auditory system in that it entails learning to associate acoustic with photic events.
Some Acoustic Relations of the Slow Cortical-Evoked Response
Authors: Davis Hallowell
Published: September 2005

The variability of the slow cortical response, vertex to earlobe, evoked by acoustic stimuli is so great from one response to the next, across conditions of the subject and across subjects, that we cannot define precise relations to parameters of the stimulus. We have established approximate functions, however, for the input-output relation and for the dependence of amplitude (peak-to-peak voltage) on the interval between stimuli. For 6 young adults, amplitude was a power function of sound intensity with an exponent of about 0.13. The level of the tone pips (2400 cps) was varied from 25 dB to 105 HL (ISO). In a few subjects, the maximum voltage of the response was more than 50 μV. Some subjects seemed to reach a plateau at moderate intensities and at outputs less than 15 μV. With increasing interval between stimuli, the responses grew, roughly exponentially, up to about 10 sec. Responses were very small at 0.5 sec and half-maximal average amplitude was usually reached at about 2.5 sec. Maximum output per minute was nearly constant for intervals from 1.0 to 2.5 sec. Both the input-output function and the relation to the interval between stimuli differ markedly from the corresponding relations of loudness. [Work supported by grant B-3856 from the National Institute of Neurological Diseases and Blindness, National Institutes of Health, U. S. Department of Health, Education, and Welfare.]
Sensation of Hearing in Electromagnetic Fields
Authors: Ingalls Clyde E.
Published: September 2005

A series of experiments is described in which radar transmitters operating at 1, 3, and 10 kMc/sec were heard. The process of hearing did not involve the ear, but apparently included only the brain and nervous system in the immediate vicinity of the brain. The effect takes place at energy levels that are considered safe for exposure all day. The effect is suggested as a means of aiding in the location of hearing difficulties. It is also discussed in connection with reports of the hearing of meteors and aurora.
Harmonic Distortion of Spherical Sound Waves in Water
Authors: McDaniel Oliver H.
Published: September 2005

A study has been made to determine the causes of harmonic distortion in spherically propagating high-intensity underwater sound waves. It is shown analytically that finite-amplitude effects are not negligible and are the predominant cause of second-harmonic distortion. A comparison between calculated third-harmonic finite-amplitude distortion and distortion measurements indicates that third-harmonic distortion is generated by other mechanisms. A brief discussion of the possible causes of the third- and higher-order harmonics is included.
Effect of Turbulence on a Distant Transducer
Authors: Heaps H. S.
Published: September 2005

When a transducer of finite size is used to measure the spectral density of a turbulent sound field, the recorded values are dependent upon transducer size. The dependence has been described in the literature. If the transducer is separated from the turbulence by a nonturbulent madium or by an elastic layer, then the recorded spectral density is a function of both transducer size and layer thickness. Analysis of the resulting situation is the purpose of the present paper.
Ultrasonic Impedance Matching from Solids to Gases
Authors: Lynnworth L. C.
Published: September 2005

Using impedance matching, one may increase the transmission of ultrasound across solid-gas interfaces, and thus increase the transmission range of ultrasound in gases. This is illustrated by theoretical predictions, and experimental results in the 1- to 3-Mc/sec range. Analysis and probe designs are presented for nonresonant, resonant, and composite matching systems. For a fused silica-air system, a nonresonant water layer improves transmission of ultrasonic pulses by 5 dB. A resonant water layer increases transmission by 11 dB. In addition, methods for achieving significantly larger transmission gains are presented. The resonant acoustic system is compared in some detail with analogous cases in optics and microwaves. Expressions for the Q and bandwidth of resonant acoustic systems are derived. An acoustic-impedance nomogram for estimating energy-transmission coefficients between pairs of materials is also described.
Ultrasonic Determination of Elastic Moduli to 2000°C, Using Momentary Contact
Authors: Carnevale E. H. , Lynnworth L. C. , Larson G. S.
Published: September 2005

Earlier determinations of Young's modulus up to 2000°C by pulse and resonance methods are briefly reviewed. A pressurized oven, ultimately capable of operating at 3600°C, is described. This oven, together with pneumalically actuated momentary contact probes, is used for elastic moduli and Poisson's-ratio determinations up to 2000°C. longitudinal- and shear-wave velocities are measnred at 1 Mc/sec in a sample 114 in. diam by 1 in. long. Results are given for refractory and other materials, some of which exhibit phase transformations, recrystallization, and grain growth ill the 1000°–2000°C range. Analysis of the temperature dependence of Young's and shear moduli shows that over wide temperature excursions the percentage changes in both moduli are equal. The determination of elastic moduli from measurement of longitudinal velocity plus either thin-rod compressional velocity or flexural resonant frequency is also described, with tungsten as an example up to 1800°C.
Thermal Stress-Wave Propagation in Hollow Elastic Spheres
Authors: Tsui T. , Kraus H.
Published: September 2005

In conventional transient thermal-stress analyses, the heating rates are sufficiently slow so that the inertia terms in the equations of equilibrium are negligible and time enters as a parameter from the transient temperature in the body. Recently, one has encountered extremely high heating rates and it is necessary to reexamine the role of inertia. Such studies of extremely massive infinite and semiinfinite bodies and extremely slender bodies have been made by others. In the former, thermal-stress wave propagation without reflection was examined; in the latter, thermally induced vibrations were considered. It is of interest now to examine the effect of inertia in a body whose dimensions lie be-between these extremes. As an example, we consider a hollow sphere of arbitrary thickness subjected to a step change of temperature on its inner surface. In the solution, the propagation and reflection of thermal-stress waves in the sphere are observed. For comparison, the results of the conventional analysis are obtained as a special case. After passing to appropriate limits, the results are compared to previous analyses of slender and massive spherical regions.
Analog-Computer Investigation of Velocity Transformers
Authors: Russell L. T.
Published: September 2005

The solution of the differential equation describing the sound velocity in a rod is dependent on the variation of cross-sectional area of the rod. Analytical solutions for the velocity in the cone, the exponential, and the catinary have been found by Merkulov [L. G. Merkulov, Soviet Phys.—Acoust. 3, 246–255 (1957)]. It has been observed that these solutions are all of the same general form. This fact suggested the consideration of cylindrical transformers of a more general shape with solutions for the sound velocity of the same general form as found by Merkulov. The original differential equation when rearranged in the form of integral equations lends itself to analog-computer solution. This investigation analyzes many shapes that give a solution of the same general form as that found by Merkulov. The results are in graphical form, giving the velocity gain as a function of the ratio of the radius of the large and narrow ends of the transformers.
Phase Variation of Acoustic Surface Waves on a Periodic Surface
Authors: Miller M. K.
Published: September 2005

An analysis is made of the phase variation for a surface wave traveling along a periodic surface. For an infinitely long cylindrical suface that has small periodic variations superimposed upon it, the acoustic reactance is periodic. By application of Floquet's theorem, wavemotion at the surface is described by an infinite series. A waveguide that has a constant reactance with a small periodically varying reactance superimposed upon it is used to illustrate the analysis. Infinite determinants are used to evaluate unknown amplitude coefficients that appear in the series solution. The phase variation for a surface wave with wavenumber h = 2π/λg, which is traveling along the surface with period L, is discussed. It is shown that, as hL → π−, the phase variation is very great in the vicinity of integral values of L along the cylindrical axis and it is very small along the remainder of waveguide.
Circumferential Waves in a Gapped Cylinder
Authors: Goldsberry T. G. , Horton C. W.
Published: September 2005

Experimental evidence establishing the existence of circumferential waves in a thin-walled air-filled cylinder with a finite discontinuity in the shell is presented. The discontinuity is a 0.062-in.-wide air gap extending the length of the cylinder and the full thickness of the shell. Evidence establishing that the principle portion of the circumferential wave travels within the shell and is reflected at the air gap is presented. [Work done under contract with the U. S. Office of Naval Research.]
Speech at High Atmospheric Pressures
Authors: Fant Gunnar , Sonesson Bertil
Published: September 2005

A spectrographic study of speech recorded at various atmospheric pressures in a decompression chamber has revealed certain systematic factors concerning formant-frequency shifts that support an acoustic theory of the origin of these effects. The typical “nasal” quality is due to the shunting effects of the vocal-cavity walls. The relative loading effect of this impedance increases as the impedance level of the air cavities increases with increasing density of the air. A supplementary x-ray study at high pressure showed a normal velar function. The complete theory has implications on normal speech production. [Study supported by the Swedish Medical Research Council grants T 312 and W 267; the Swedish Technical Research Council; the National Institutes of Health, U. S. Department of Health, Education, and Welfare, under research grant NB-04003-02; the U. S. Air Force under grant AF EOAR 64-28; and the U. S. Army under contract DA-91-591-EUC-3080.]
Reflection and Scattering of Sound by the Sea Bottom. Part I: Theory
Authors: Marsh H. W.
Published: September 2005

This paper is Pt. I of a trilogy [Pt. II: T. G. Bell, “Field Data.” Paper K2, this meeting. Pt. III: H. W. Horton, “Model Studies.” Paper K3, this meeting]. Theoretical topics that are relevant to the most important effects observed in the field are discussed. These are grouped under intensity of reflection, distortion of reflected wave, and scattering, and include models predicting effects of absorbing bottoms, layered media, and irregular boundaries.
Study of the Flexural Vibration of Mass-Loaded Rings
Authors: Clark T. F. , Muster D.
Published: September 2005

An energy approach is used to study the flexural vibration of a ring mass-loaded in a plane-symmetric manner. The effects of rotary inertia and shear are neglected. Computed natural frequencies and mode shapes are compared to those obtained experimentally.
Effect of End Constraints on the Damping of Laminated Beams
Authors: DiTaranto R. A. , Blasingame W.
Published: September 2005

The use of laminated elastic-viscoelastic beams as a means for obtaining vibration damping, together with reasonable structural stiffness, has been the object of extensive theoretical and experimental investigations. The particular theoretical and experimental work considered herein is the effect of end constraints on the composite loss factor of vibrating laminated beams. According to theoretical findings, the damping of laminated beams is independent of boundary conditions and depends solely on the geometry of the beam's cross section and properties of the damping material [R. A. DiTaranto, “Theory of Vibratory Bending of Laminated Beams,” (to be published)]. To check the theory, 3- and 5-layer laminated beams were investigated for ends constrained in several different manners: namely, free-free with and without bolted ends, and both ends clamped. For both the 3- and 5-layer beams, satisfactory agreement was obtained with theory, indicating the variation of composite loss factor with frequency of vibration to be independent of end conditions.
Experimental Determination of Mutual Radiation Impedance between Coplanar Circular Pistons
Authors: Flad F. R. , Kuzneski J. A. , Packard W. B.
Published: September 2005

The normalized mutual radiation impedance between circular piston transducers mounted in a coplanar configuration is determined by an experimental procedure. The transducers used in the experiment are double mass-loaded ferroelectric tubes. The normalized mutual-radiation-impedance coefficients are calculated from the measured value of electrical admittance and the known freefield properties of the transducer. To simplify the interpretation of the data, lumped-constant equivalent electromechanical circuits with frequency-dependent elements are used. The equivalent circuit as synthesized from freefield measurements of the transducer is modified to include the effects of the mutual radiation impedance. The modified circuit permits its use in the analysis of arrays of transducers. By means of this method, experimental results are obtained for a 2-element array with a 30-in.-sq steel baffle plate and also with no baffle. The “ka” value of the piston radiators at velocity resonance is approximately 1.3, where k is the acoustic wavenumber in water and a is the radius of the piston. Data are presented for various center-to-center element spacing and piston-velocity ratios. The results obtained show the mutual-impedance coefficient to be practically independent of piston-velocity ratio. The experimental mechanical-radiation-impedance values agree with analytical results reported previously in the literature.
Random-Bearing Errors in Split-Beam Systems
Authors: Usher Theron
Published: September 2005

The performance of a linear array of 2M transducers in determining the bearing of a plane-wave random signal in a background of isotropic random noise is considered. The processing in the array is arranged by means of wide-band phase-shifting filters and infinite clippers to produce a null response when the array is “on target.” Expressions for the angular uncertainty of the null response are derived, and the filter parameters that minimize this bearing uncertainty are determined. An expression for the minimum bearing uncertainty is also derived for arbitrary signal and noise spectra and also for a case employing well-known models for signal and noise spectra. The bearing uncertainty of a system with simple filter characteristics is determined and compared with the minimum bearing uncertainty. [Work done at Yale University as part of research supported by Electric Boat Company and U. S. Office of Naval Research.]
Pressure Pulses of Small Explosions at Great Depths in the Ocean
Authors: Blaik Maurice , Christian Ermine A.
Published: September 2005

In several underwater-explosion studies during the past 15 years, small charges have been fired at ocean depths as great as 3 miles and pressures recorded nearly vertically above the charge so that refraction and scattering effects were negligible. In these tests, the charge weights varied from several hundredths of a pound to as much as 10 lb. The instrumentation in many cases was capable of reproducing wide-band response from a few cycles per second up to as much as 50 kc/sec. An unclassified sample of these numerous data has been analyzed in detail. The variables considered include shock-wave rise time, peak pressure, and decay time, as well as bubble-pulse critical pressures and times. The results permit an extension of the existing semiempirical formulas by an order of magnitude in many cases. The most significant changes in the equations involve the smallest charges at the greatest depths and distances from the pressure gauges. The reduced distance parameter R/W12 is extended from Arons (1954) limit of about 2000 to the order of 30 000.
Critical Evaluation of SAL Audiometry
Authors: Jerger James , Wood Susan
Published: September 2005

Previous attempts to validate the SAL audiometric procedure by comparison with conventional bone-conduction (BC) audiometry have been subject to two sources of error: (1) the occlusion effect produced by standard earphone cushions and (2) proper masking of the nontest ear during conventional BC audiometry. This study removed the occlusion effect as a source of error by employing earphones enclosing a very large volume (M. P. Pedersen, type B228-A). The masking problem was eliminated by employing, as experimental subjects, only individuals whose nontest ear showed a severe or total sensorineural hearing loss. Under these conditions, SAL and conventional BC thresholds were measured with a Békésy audiometer, in plugged normal ears and in ears with both conductive and sensorineural hearing loss. In all groups, SAL and BC results were equivalent. The effects of force of application of the bone vibrator, linearity of the masking effect, duration of SAL noise exposure, and direction of frequency changes of the Békésy audiometer are also considered. [Study supported by the Vocational Rehabilitation Administration under research grant RD-1297S.]
Temporary Threshold Shift in Males and Females
Authors: Ward W. Dixon
Published: September 2005

In an extended study of auditory susceptibility, 20 different tests involving temporary threshold shift (TTS) have been administered to 24 male and 25 female, young, normal adults. This paper discusses three features of the average results: (1) low-frequency noises and tones, presented via earphones, produce more TTS in males than in females, though at high frequencies the reverse is true; (2) the fact that men have ears that are larger and project farther from the head apparently makes them more susceptible to directional field-exposure noise; (3) significantly less TTS is produced by binaural exposures to low- and mid-frequency stimuli than by monaural exposures, presumably because of middle-ear-muscle action; however, this tendecy is independent of sex. [Work supported by the Public Health Service, U. S. Department of Health, Education, and Welfare, under grants NB04403 and NB-K3-18,740.]