bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Analog for a Psychophysical Task
Authors: Schoeffler M. S.
Published: September 2005

In the theory of signal detectability, it is assumed that the perceived magnitude of a stimulus can be represented as number, and the biases resulting from response preferences or decision theoretic considerations affect only the criterion that is used. In order to examine these assumptions, an experiment was conducted in which observers were presented three digit numbers, each of which was drawn from one of two normal distributions. Observers were required to respond “high” or “low” to each number and feedback was provided. Three a priori probabilities were used. The results indicate that the variance of the criterion and response latencies decrease with practice; that correct responses for extreme values of the stimulus have shorter latencies than those for intermediate values; and that the response corresponding to the more frequently presented stimulus has a shorter latency than the other response. The relevance of the results to the interpretation of psychophysical data is discussed.
Detection of Auditory Signals in Restricted Sets of Reproducible Noise
Authors: Pfafflin Sheila M.
Published: September 2005

The detectability of auditory signals in reproducible random noise was studied under two conditions: a single noise used throughout a block of 288 trials, and 12 noises occurring at random but with equal frequency throughout a block of trials. Both 2-interval forced-choice judgments and judgments of the presence or absence of the signal in single-noise samples were obtained in separate blocks of trials. On individual trials of the forced-choice judgments, the same noise appeared in both intervals. The noises were stored numerically in a PB-250 computer and converted to sound during the experiment by means of a digital-to-analog converter. The signal frequency was 312.5 cps. Signal detectability was found to be significantly better when a single noise was present in a block of trials. Performance was poorer for presence-absence judgments than for forced-choice judgments. The results support the importance of memory from trial to trial in the detection process.
Influence of D-amphetamine, Benactyzine, and Chlorpromazine on Performance on an Auditory Vigilance Task
Authors: Loeb M. , Hawkes G. R. , Evans W. O. , Alluisi E. A.
Published: September 2005

Detections, false responses, and response latencies were measured for subjects monitoring auditory signals (more-intense noise pulses in a periodic-noise pulse train) over a 1-h period following administration of a stimulating drug (D-amphetamine), an antiadrenergic tranquilizer (chlorpromazine), an anticholinergic tranquilizer (benactyzine), and a placebo. It was tentatively concluded that changes in performance over time following administration of the placebo could be explained in terms of shifts in subjects' criteria for responding and that, following administration of the tranquilizer, shifts both in effective sensitivity and response criteria were occurring. Following injection of D-amphetamine, performance remained relatively constant throughout the monitoring period.
Effect of Very-Low-Frequency Pure Tones on Auditory Threshold
Authors: Jerger James , Alford B. , Coats A. , French B.
Published: September 2005

Nineteen human subjects were exposed to high-intensity (119–144 dB SPL) low-frequency (2–12 cps) sinusoids for successive 3-min periods. Auditory thresholds over the range from 100 to 8000 cps were continuously monitored before, during, and after exposure by a Békésy-type tracking technique. Eleven subjects showed temporary threshold shifts (TTS) of 10–22 dB after a variable number of exposures. All TTS's were confined to the frequency region from 3000 to 8000 cps. Frequencies of 7 and 12 cps produced considerable masking over the range from 100 to 4000 cps. [This study was supported by the National Aeronautics and Space Administration.]
Reliability of Temporary Threshold Shifts Resulting from Repeated Exposure to Impulse Noise
Authors: Hodge David C.
Published: September 2005

Twenty-two subjects were trained in the use of a Békésy-type audiometer and subsequently exposed 9 times to the same noise condition. The noise exposure consisted of 50 rounds fired from a .30-cal small arm, 5 sec between rounds, with the subject's left-ear canal oriented normal to the gun muzzle at a point where the peak SPL was 155 dB. Measurements of TTS at 6 frequencies between 500 and 6000 cps were converted to TTS2 for ease of comparison. The over-all fluctuation in mean TTS2 was 5 dB or less for all 6 test frequencies, and fluctuations in the standard deviations were likewise small. No obvious upward or downward trends in mean TTS2 were found to extend across the 9 exposures. Individual differences in TTS2 were quite large, however, and the reliability coefficients in general were small. These findings were interpreted as indicating that group data are more meaningful than those for individual subjects, and that the use of very small samples of subjects in impulse-noise studies should be avoided.
Ultrasonic Absorption in Biological Media
Authors: Dunn Floyd
Published: September 2005

A selected review of the ultrasonic absorption characteristics of biological media, including tissues and solutions of biologically important molecules, as a function of frequency, temperature, amplitude, etc., is presented.
Ultrasonic Absorption in Aqueous Solutions of High-Molecular-Weight Polysaccharides
Authors: Hawley S. A. , Kessler L. W. , Dunn Floyd
Published: September 2005

The absorption of ultrasound in tissue exhibits a linear dependence upon frequency over several decades. It has been shown that measured values of the protein absorption coefficients for blood and its components fall in the magnitude range to account for the major fraction of the tissue absorption [Carstensen and Schwan, J. Acoust. Soc. Am. 31, 305–311 (1959)]. The present study was undertaken to determine the importance of a contribution absorption in tissue by molecules not constrained by a tertiary structure. The absorption in high-molecular-weight polysaccharides in aqueous solution were investigated as a function of frequency, concentration and molecular weight. The results presented lend support to the current view that protein structures are considerably more responsible than molecular configurations lacking tertiary structure for the observed absorption spectrum in tissue. [This work is supported in part by the U. S. Office of Naval Research and in part by the National Institutes of Health, U. S. Department of Health, Education, and Welfare.]
Effects of Ultrasound on the Ultrastructure of Liver Cells of the Mouse
Authors: Curtis Joseph C.
Published: September 2005

Previous studies have shown that the frequency distribution of mice with hepatic lesions produced by ultrasound is strongly dependent upon heating effects. Alterations in cell fine structure by focused 1-Mc/sec ultrasound have been examined in an attempt to determine the nature of subcellular changes characteristic of dose levels producing little or no tissue heating. Liver was irradiated in situ, the animals sacrificed immediately, 1, and 24 h later, and the exposed tissue examined with the light and electron microscopes. While all subcellular components were altered by ultrasound at high dose levels, the endoplasmic reticulum and mitochondria appeared most strongly affected. Extensive damage to the endothelial cells forming the walls of the blood vessels was also apparent. Pulsed ultrasound, at moderate dose levels, produced a marked, localized disruption of cell fine structure, cytoplasmic organelles in adjacent regions appearing relatively undisturbed. Histochemical and ultrastructural changes indicate that the cytoplasmic membranes involved in glycogen storage are particularly sensitive to ultrasonic energy. The electron-microscopic observations are discussed in terms of several possible mechanisms of ultrasonic action.
Ultrasonic Absorption in Solutions of Amino Acids
Authors: Barrett Robert E.
Published: September 2005

Measurements of the ultrasonic absorption coefficient in aqueous solutions of amino acids have been made. The dependence on frequency resembles that found in some salt solutions. In particular, for solutions of valine and of glycine ethyl ester hydrochlorie, the value of 2 α/ν2 is greater than that in pure water at the lower frequencies—by about 50% at 15 Mc/sec—and below that in water at the higher frequencies—by about 10% at 150 Mc/sec. [Work supported by the National Institutes of Health, U. S. Department of Health, Education, and Welfare.]
Acoustic Power Radiated by a Source of Sound in a Duct
Authors: Maling George C.
Published: September 2005

The acoustic power radiated by a point monopole in a duct has been calculated. The contributions from the 2-dimensional array of images have been added by an IBM-7094 computer. The method used ensures that rapid convergence of the series is obtained. Calculations are presented for pure tones and for bands of noise, as well as for constant-strength and constant-pressure sources. The results are compared with measurements of the power radiated by an aerodynamic noise source in a 50-ft duct terminated by a 16-ft absorbing wedge.
Laboratory Simulation of the Response of Structures Exposed to Intense Acoustic Environments
Authors: Bozich Daniel J.
Published: September 2005

The primary state-of-the-art laboratory method for the evaluation of the response and fatigue characteristics of skin panels exposed to intense noise is the progressive-wave or parallel incidence test facility. This method obtains the highest sound-pressure levels per unit input power by minimizing the cross-sectional area of the duct and also maintains a relatively flat frequency response. However, many of the current configurations provide excessive radiation damping to the panel in its lower modes. This paper summarizes analytical and experimental investigations of the radiation damping of panels mounted in progressive-wave test sections. The results are presented in generalized form, which give the dependency of the radiation damping on the ratio of the panel area to test duct cross-sectional area and pertinent panel parameters. In addition, the paper reviews an analytical study of the response of panels to variable incidence progressive waves and to a reverberant field. These results demonstrate the possible future importance of reverberant fields as a replacement for progressive-wave tests.
Noise Environment of Restaurants
Authors: Harris A. S. , Watters B. G.
Published: September 2005

In recent field and laboratory studies, we have investigated the reactions of diners to the noise environment in restaurants. Two dominant components of such an environment are typically a continuous level of reverberant, unintelligible speech sound, and clearly intelligible speech from diners at nearby tables. Our studies show that the unintelligible speech is important in masking otherwise intelligible speech. Ideally, the level of the masking sound will be great enough to cover up speech from nearby diners, but not so high that it interferes with conversation between diners at the same table. It appears that the range of levels over which both of these requirements are satisfied is rather narrow.
Vehicular-Traffic Noise near High-Speed Highways
Authors: Brasch Jerome K.
Published: September 2005

Magnetic-tape recording near an interstate dual highway—in area of level terrain, at distance of 100 ft from pavement, with taffic counts being made—has been conducted with the purpose of describing, physically and quantitatively, vehicular-traffic noise near high-speed highways. Playback of recorded noise and preparation of charts with over-all and octave-band sound-pressure levels, and with A- and B-frequency-weighted sound levels, have been accomplished. Peaks of traffic noise having over-all levels at and above 80, 85, 90, and 95 dB have been tabulated. Graphs of cumulative time versus overall level, and octave-band analyses for approximately 200 peaks of 85 dB or greater over-all level, have been made. Loudness and loudness level have been calculated according to the method (Mark VI) of S. S. Stevens. Over-all sound-pressure levels were mainly in the range of 65–100 dB, with significant numbers of peaks over 90 dB. Virtually all peaks in excess of 80 dB over all were due to trucks and of a low-frequency nature. The best quantitative index of such noise exposure may be the graph of cumulative time versus level cited above.
Selection of an Objective Measure for Motor-Vehicle Noise
Authors: Galloway W. J.
Published: September 2005

Subjective rating experiments performed by Callaway et al. with 15 observers rating 97 Diesel truck noises and by Robinson et al. with 57 observers rating 147 passenger car, truck, and motorcycle noises have been analyzed to evaluate an optimal measure for predicting average response on category rating scales. The Callaway data were used to compute loudness level (Stevens), perceived noise level, speech-interference level, and A-scale sound level. Callaway's over-all SPL and equivalent-tone loudness calculations were used to compute the same functions. His computations of loudness level (Zwicker) were also used. Regression analyses, correlation coefficients, and confidence intervals relating each computed or measured quantity to mean subjective rating were computed for each vehicle class and the composite of all vehicles. It is concluded that A-scale sound level performs as well or better than any of the other measures as a predictor of average subjective rating, yielding correlation coefficients in the range from 0.86 to 0.98, with a coefficient of 0.97 for the composite set of vehicles.
Implementation of Vocal-Response Synthesizer
Authors: Hogue V. D.
Published: September 2005

A circuit-implementation method is described for the improvement of synthesized speech, using a channel vocoder, by trying more closely to approximate the actions of the vocal tract that produce the original speech sounds. The method described electronically shapes the synthesized speech without the necessity of bandpass filters. Particularly, the description relates to the method and the apparatus needed to synthesize the characteristics of the human vocal mechanism with respect to the bandwidth and transient response of the vocal cavities.
Speech-Compression Simulation Compiler
Authors: Rader Charles M.
Published: September 2005

Speech-compression systems can often be profitably studied by digital-computer simulation. The computer programming of such systems can be greatly simplified by the use of a compiler called PATSI, which is described in this talk. Using PATSI, which has been realized on the TX-2 computer, an engineer without programming experience can produce a system-simulation program by inspection of the block diagram of the system. If his system contains unusual elements, he can define them for the compiler, again without programming experience. Unlike BLODI, the other major block diagram compiler known to the author, PATSI is intended for on-line computer investigations. Thus a simulation may, if desired, include elements whose parameters the user can vary while the system is operating. The user may also view on an oscilloscope the waveforms, Lissajous figures, etc., at any points in the system. These properties often make it easier to study the simulated system than the actual system in the laboratory. Several new speech compression devices have been studied using PATSI, and the results of the simulations have been available much sooner than would have been possible with conventional programming techniques.
Medium-Bandwidth Speech-Compression Device
Authors: Teacher C. F. , Jurenko D. M.
Published: September 2005

This paper describes a medium-band-width compression system that is aimed at system simplicity, high intelligibility, and good voice quality. The system is designed to operate between 4800 and 9600 bit/sec. The device, called MAFAC (Multiple Amplitude and Frequency Audio Communicator), divides the speech spectrum into four unequal parts. The analyzer extracts an amplitude and frequency parameter from each of the channels. The parameters are band-limited and digitalized in such a way as to enable the transmission to fall within acceptable limits. Speech is resynthesized at the receiver by means of four multivibrators and modulators. Several variations of this system are discussed and results given. The MAFAC system is compared to other speech-digitalizing techniques such as delta modulation, pulse-code modulation, and clipped speech. [This work has been partially supported by the U. S. Army Electronics Laboratory, Fort Monmouth, New Jersey.]
Interpretation of Results Obtained in Medical Ultrasonic Tomography
Authors: Belford John F. , Uphoff R. L.
Published: September 2005

The use of ultrasound in medical diagnosis has been known and experimented with for some 20 years. It is only in the last few years that its application has become fairly widespread, primarily because of the high correlation factors obtained by investigators in the neurological field in the Scandinavian countries using stykographic (A-scan) techniques. Now, more-sophisticated methods, such as ultrasonic tomography, are beginning to appear in the neurological area. While some equipment is available that is capable of localizing many intracranial masses, work remains to be done in the interpretation of the resulting tomograms. Because physicians, on the one hand, are generally unfamiliar with the properties of ultrasonic waves and their interaction with matter and physicists, on the other hand, are not well-acquainted with human anatomy, physiology, and pathology, close cooperation is needed between the disciplines of acoustics and medicine to ensure successful advancement of medical ultrasonography. A discussion of some of the biological and physical factors involved and a report of recent progress is given. The neurological area is chosen for discussion because almost all possible factors of importance in interpretation are found here. The conclusions apply to other body areas.
Periodicity Patterns of Bullfrog and Cat Neurons
Authors: Moushegian George , Rupert Allen , Langford Ted L.
Published: September 2005

Interspike-interval distributions to acoustic stimulation were obtained from neurons located in homologous structures of bullfrog (Rana catesbeiana) and cat (Felis domestica). When stimulating frequencies were the same, distributions of periodicities for these presumably homologous neurons were strikingly similar. This remarkable comparability was also the case when intensity was varied and frequency held constant. These results indicate that some neurons at lower levels of the brain of phylogenetically disparate organisms respond to acoustic stimulation in an identical manner. An important difference, thus far observed, between neurons in frog and cat is the frequency beyond which no intrafiber volleying is possible. In frog, it is near 400 cps, whereas in cat it is around 2.0 kcps. Some neurons in frog that are unresponsive to sound are driven by vibratory stimuli and give interspike-interval distributions that cannot be distinguished from distributions in which the stimulus was sound. Evidence is also presented for a type of neuron, in frog, that has a trimodal interspike-interval spontaneous pattern. Upon acoustic stimulation, these neurons evidence only inhibition that acts selectively, depending upon intensity, on one of these modes.
Single-Unit Activity in the Inferior Colliculus of the Guinea Pig
Authors: Marseillan Ricardo F. , Mundie J. Ryland
Published: September 2005

The sound-induced electrical activity of 124 units was recorded with glass microelectrodes in the exposed inferior colliculus of 34 guinea pigs anesthetized with sodium pentobarbital. Pulse-occurrence histograms and discharge-rate analyses were carried out in real time with a digital computer. The response patterns varied from complete suppression of background activity to continuous firing, but generally showing both excitatory and inhibitory effects, in most instances dependent on frequency and/or intensity of the stimulating sound. The individual neurons showed a consistent low- to high-frequency tonotopical arrangement in depth from the collicular surface.
Pure-Tone Masking in the Cochlear Nerve of the Golden Hamster
Authors: Finck Alfred
Published: September 2005

Slow, negative-potential elevations were recorded by microelectrode from the hamster cochlear nerve in response to pulsed tones. Masking effects produced by continuous tones on the response to a single pulsed tone were studied. Masking was defined as the ratio between the pulsed-tone response and the response to pulsed-continuous tone combinations. The results indicated rather broad, complicated masking patterns for tonal combinations having similar intensity levels (dB SPL). When the continuous-tone (the masker) intensity was decreased relative to the pulsed tone, response amplitude often appeared reduced at frequencies just above the pulse-tone frequency. The effects of varying masker frequency and intensity on the slow eighth-nerve potential appear favorably related to psychological studies of tone-on-tone interactions. [This work supported in part by the National Institute of Neurological Diseases and Blindness, National Institutes of Health, U. S. Department of Health, Education, and Welfare.]
Subharmonic Generation in the Peripheral Auditory System of Rodents
Authors: Dallos Peter J. , Linnell Craig O.
Published: September 2005

Of the various types of distortion evident in the cochlear-microphonic potential during stimulation with high-intensity sound, the generation of subharmonics has received very little attention in the past. This paper presents a systematic investigation of this phenomenon. Cochlear potentials were recorded from pairs of wire electrodes placed into various turns of guinea pig and chinchilla cochleas. Pure-tone sound stimuli in the frequency range of 100 cps–20 kcps were delivered by the closed-tube method. The presence of subharmonic components was demonstrated in all turns of the cochlea. The subharmonic potentials possess very high threshold, after which they immediately jump to a high magnitude. Increase in stimulus intensity above the threshold level first produces a gradual increase in the subharmonic; rapid saturation and eventual decline follows within an extremely narrow dynamic range. The predominant frequencies of the subharmonic distortion products are 12 and 14 of the driving frequency; their magnitude is commensurate with that of the fundamental. [Work supported by the National Institutes of Health, U. S. Department of Health, Education, and Welfare.]
Effect of Potassium Chloride on the Effective Resistance of the Cochlear Partition
Authors: Konishi Teruzo , Singleton George T.
Published: September 2005

By measuring potential drop produced by a constant current across the cochlear partition between scala media and scala tympani of the basal turn in guinea pigs, the effective resistance was found to be 3500 to 5000 Ω. Simultaneous recording of the effective resistance and of the cochlear potentials, as the exploring electrode penetrated the organ of Corti, revealed that the reticular lamina possesses the main part of this resistance. When potassiumrich isotonic solution was injected into scala tympani, it caused a temporary increase of the effective resistance, accompanied by a temporary increase of the negative summating potential. The recovery of the summating potential preceded that of the effective resistance. The locus of this reversible change in the effective resistance across the cochlear partition was found to be in the reticular lamina, not in the basilar membrane. Increasing the potassium concentration in scala tympani served to abolish temporarily the action of the hair cells and also temporarily the electrical resistance of reticular lamina. The relation of the effective resistance across reticular lamina to other electrical events in the cochlea is discussed.
Input-Output Characteristics of the Lateral-Line Organ of Xenopus laevis
Authors: Harris G. G. , Petraitis R. , Milne D. C.
Published: September 2005

In Xenopus laevis, the lateral-line system may be considered as a single organ, containing about 20 000 hair cells, that is used to detect moving objects. From anatomical and neurophysiological evidence, it appears to be organized in groups of sensory buds, called stitches, which are directionally sensitive, probably to velocity. Each stitch is innervated by two large myelinated afferent fibers and by a few small myelinated and unmyelinated fibers, which may be efferent. Electrophysiological recordings made from a piece of skin in vitro show that the two large fibers are spontaneously active and sensitive to motion in opposite directions. The spontaneous activity in each fiber is independent of spontaneous activity in the other, indicating that the origin of spontaneous activity cannot be Brownian motion of the cupula. Interval histograms of spontaneous activity show an exponential tail for long intervals and a decrease in the number of small intervals. There is a characteristic absence of intervals less than about 10 msec. Evoked responses are repetitive with rate, number of spikes, and latency, dependent on intensity. These results indicate that both place and pulse-position coding is used to convey the information necessary for the perception proper to this organ.
Problems Presented by Theatre-in-the-Round
Authors: Fitzroy Dariel
Published: September 2005

For Theatre-in-the-Round, the stage is located in the center, with the audience seated 360° around the presentation. Lighting, microphones, and other similar accessories are suspended above the acting areas. This type of theatre originally started in relatively small rooms, where acoustical problems were much less complicated. When such a type of entertainment is presented in an auditorium intended for large audiences (2500–3000), there are substantial problems presented. This paper details expedients employed in solving these problems.
Sound Reinforcement for the Los Angeles Pavilion
Authors: Veneklasen Paul S.
Published: September 2005

The requirement of sound reinforcement in the 3250-seat auditorium for performance of plays and light opera was recognized and stressed from the beginning of design. Successful reinforcement must be carefully integrated with good acoustical design. A basic 5-channel stereophonic system is used to preserve naturalness, apparent source position and movement, and apparent perspective on stage. Either nondirectional microphones can be used to preserve stage reverbance with musical ensembles, or cardioid-type microphones can be used to accentuate intelligibility. Five loudspeakers are hidden in the proscenium arch. Microphones can be suspended or mounted invisibly in the floor. Data is presented to demonstrate the degree of coverage over the stage area of a single set of microphones. Three channels of additional loudspeakers are provided upstage for solo balance or for pit-orchestra transfer. Operation can be from the audience area or from the equipment room using CCTV and a binaural transfer. In the latter case, the operator has many other monitoring facilities available. Data on available gain are also presented. The success of natural reinforcement without visible appurtenances has been verified.
Provision for Adequate Loudness in Recently Built Auditoria
Authors: Doelle Leslie L.
Published: September 2005

Provision for adequate loudness is one of the five basic requirements for good hearing conditions in auditoria. It has been achieved in the discussed and illustrated examples by the following means: acoustically beneficial room shape, keeping floor area and room volume at a reasonable minimum, the use of suitably dimensioned and properly located sound-reflective surfaces, supply of maximum amount of direct sound from source to audience, and strict reverberation control. Ceilings well-integrated with mechanical, structural, and electrical components constitute important elements in the provision for adequate loudness.
Acoustical Design of Small Rooms
Authors: Schultz Theodore J. , Figwer J. J.
Published: September 2005

In the acoustical design of small rooms, such as music practice and rehearsal rooms, small broadcast studios, or monitoring facilities, two aspects of the low-frequency sound field pose special problems: one has to do with the “steady-state” transmission of sound from one place to another in the room and is related to the sparseness of normal modes at low frequencies; the other has to do with the decay of sound (i.e., the transient response of the room) and is related to the inefficiency of most sound-absorbent materials at low frequencies. Both aspects of the problem lead to conditions that are described as “boomy,” but for different reasons. Both problems can be dealt with by providing adequate absorption at low frequencies. Design criteria, quite different for rehearsal rooms, speech studios, and monitoring facilities, are presented; and recommendations are made for meeting these criteria.
Spectrum-Envelope Method for Synthesis of Oboe Tones
Authors: Strong William J.
Published: September 2005

Oboe tones ranging in fundamental frequency from 232 to 931 cps were synthesized with an IBM-7090 computer. Each oboe tone was synthesized by using up to 30 harmonics separated into three groups. Each group was controlled independently of the other two groups with respect to its amplitude as a function of time. For synthesis purposes, the relative amplitudes of the harmonics were obtained from an idealized spectrum envelope for the oboe. In forced-choice testing, the synthetic oboe tones were identified as oboe tones 73% of the time. (The natural oboe tones were identified as oboe tones only 75% of the time.) The spectrum envelope is discussed in terms of how it affects the identification of oboe tones. [Work performed at the Massachusetts Institute of Technology with support from the National Association of Music Merchants.]
Bass Violin and the Seven-Foot Contrabass Violin
Authors: Hutchins Carleen M.
Published: September 2005

The development of the two largest instruments in the new violin family, the bass violin and the contrabass violin, present some interesting complications in scaling for desired resonance placement and other physical factors, as well as for tone quality and size of musicians. The two instruments are discussed and demonstrated. [Work supported by the John Simon Guggenheim Memorial Foundation and the Catgut Acoustical Society.]
Measurements of Clarinet Resonance Frequencies
Authors: Backus John
Published: September 2005

Equipment has been constructed to record the resonance frequencies of the modes of vibration of the clarinet air column when closed at the mouthpiece end and to compare these with the harmonic frequencies of the fundamental mode. An external driver provided with a servo regulator maintains a constant sound pressure at the open end of the clarinet as the frequency is swept through the desired range. A microphone is inserted in the clarinet mouthpiece and records the relative amplitudes of the resonances on a strip-chart recorder. A specially constructed electronic circuit provides marks on the same chart at the harmonic frequencies of the fundamental mode for comparison purposes. A brass tube sounding the same fundamental frequency as the full length clarinet shows 25 resonances, the first 7 coinciding well with the odd harmonics 1–13. The full-length clarinet shows only 11 prominent resonance, of which only the first 3 coincide reasonably well with harmonics 1, 3, and 5. On ascending the scale, the number of resonances decreases to three just before the “break.” Above this point, the resonance frequencies apparently bear only a random relationship to the harmonic frequencies.
Demonstration of a Hydraulic Model of the Cochlea having a Soft Partition Lengthwise
Authors: Meyer Max F.
Published: September 2005

I introduce fundamental facts requiring explanation: First: Giuseppe Tartini in 1704 discovered that, when two musical tones were presented to it, the sense organ not only gave him the musical interval but added one or more bass tones, which he named terbi suoni. In 1954, Max F. Meyer extended this discovery over nonmusical intervals and also showed that the terzi suoni failed to deserve the Helmholtzian term “difference” tones. Example: For the interval 19:13, the terzi suoni are the frequencies 7 and 3, by no means 6. Second: About 1830, Rudolf Koenig made known the remarkable fact that in all mistuned consonances the beats of the higher and those of the lower pitch were never heard at random times: they always strictly alternated. Third: To this, Carl Stumpy in 1895 added the discovery that the beats of 1:2 and 3:2 (because odd:even) mistuned by “d” came at the rate of “2d,” i.e., were doubled.—The demonstrated model prescribes the fruitless place theory and offers a mechanism by which all those facts of audition are explainable as heard frequencies.
High-Temperature Acoustics Techniques and Applications
Authors: Carnevale E. H.
Published: September 2005

A survey of acoustical studies at temperatures above 1000°K is presented. Special emphasis is placed on recent work in gases, molten materials, and solids. Although relatively little has been done in this field, recent interest in high-temperature technology has stimulated the development of new techniques with special applications. The studies include the measurement of thermodynamic and physical properties, as well as provide information on molecular processes. The techniques used in the determination of temperature, transport properties (viscosity, thermal conductivity, and diffusion), relaxation times, elastic moduli, etc., are presented. A description of the high-temperature sources required in the measurements include dc plasma jets, ac induction heaters, ovens, and shocktubes.
Propagation of Hypersound in Benzene
Authors: Piercy J. E. , Hanes G. R. , Turner R.
Published: September 2005

The light scattered from the beam of a single-mode helium-neon laser by the thermal motion of the molecules of liquid benzene has been analyzed with a Fabry-Perot interferometer. From the observed frequency broadening and displacement of the Doppler-shifted (Brillouin) components, values have been derived for the absorption and velocity of sound in the frequency range 1–5 Gc/sec. The absorption is in approximate agreement with that expected from the relaxation of the total vibrational specific heat, and, together with values of the absorption at ultrasonic frequencies from the literature, defines a relaxation frequency of 0.8 Gc/sec. The velocities, however, when compared to ultrasonic values indicate a dispersion approximately half that expected for this relaxation. Possible origins of this discrepancy are discussed.
Acoustic Beam Probing, Using Optical Techniques
Authors: Cohen M. G. , Gordon E. I.
Published: September 2005

It is demonstrated that the amplitude of the light deflected or scattered by an advancing sinusoidal acoustic wave, as a function of the angle between the direction of light propagation and the acoustic wavefront, is proportional to the Fourier transform of the amplitude distribution of the acoustic wave in the plane of the wavefront. Studying the angular dependence of the optical-acoustic interaction determines accurately and directly the angular distribution of far-field diffraction pattern of the acoustic beam and determines incidentally the angular response of the acoustic transducer producing the beam. The angular resolution equals the angular spread in the probing light beam. Experiments illustrating and verifying the technique are described.
Acoustic Beam Probing, Using Optical Techniques in Lossy Media
Authors: Gordon E. I. , Cohen M. G.
Published: September 2005

The effect of volume acoustic loss is determined. It is shown that loss does not change the consideration of the preceding abstract [M. G. Cohen and E. I. Gordon. Paper T5, this meeting] apart from a slight reduction in angular resolution, unless the decay distance is comparable to the acoustic wavelength. The loss parameter does introduce a maximum usable acoustic beam width for the interaction (coherence width). In addition, techniques for determining the acoustic loss are described. Particular attention is given to the near- and far-field energy distribution of the scattered light beam. It is shown that the farfield distribution is Lorentzian only under special circumstances. Consideration is given to probing light beams with a uniform intensity distribution of finite width as well as beams with Gaussian intensity distribution. Edge effects are taken into account, and it is shown that these can make important contributions to the lineshape as well as lead to errors in the interpretation of phonon lifetimes from scattering experiments. Experiments confirming the results are described.
Bragg Reflection by Ultrasonic Waves—Fresnel Region
Authors: Klein W. R.
Published: September 2005

By treating the ultrasonic light-diffraction problem as a two-boundary problem and matching solutions of the appropriate wave equations at these boundaries, an expression for the light-intensity distribution in the Fresnel region is obtained for arbitrary experimental conditions. The case of Bragg reflection by high-quency ultrasound is discussed. [Work supported by U. S. Office of Naval Research.]
Monaural and Binaural Discrimination against Competing Sentences
Authors: Carhart Raymond
Published: September 2005

PB-50 lists were presented in a sound field against a background of spoken sentences. Four signal-to-noise ratios plus one quiet condition were used. Test items came from a loudspeaker to one side of the subject and competing sentences from a second loudspeaker, on the opposite side. Sixteen normal hearers underwent both test and retest under one binaural and two monaural conditions. Discrimination functions for these conditions showed similar configurations, but were displaced from one another along the signal-to-noise axis. Head-shadow effects caused poorer discrimination during monaural listening when test items come from the far side of the head. Monaural efficiency with the open ear facing the source of test items was almost as good as binaural efficiency. However, binaural performance here exhibited an advantage equal to approximately a 3-dB shift in signal-to-noise ratio, despite the fact that the head-shadow effect enhanced interference in the far ear by almost 13 dB. [Work supported by the Veterans' Administration and by the National Institute of Neurological Diseases and Blindness, National Institutes of Health, U. S. Department of Health, Education, and Welfare.]
Method for Measurement of Speech Identification
Authors: Speaks Charles , Jerger James
Published: September 2005

A new method for measuring speech-identification behavior is described. Thirty closed-message sets were constructed. Each set contained 10 synthetic sentences, representing 4 levels of approximation to a “real” sentence. Sentence length and informational content were controlled. Message identification under conditions of low-pass filtering and periodic interruption was studied in 30 subjects. Performance varied systematically with informational content. Articulation functions under normal and degraded conditions are compared with analogous functions for more conventional-speech audiometric materials. [This investigation was supported by National Institute of Neurological Diseases and Blindness, National Institutes of Health, Public Health Service, U. S. Department of Health, Education, and Welfare.]
Comparison of Information in Certain Multidimensional Acoustic Signals
Authors: Chaney Robert B. , Webster J. C.
Published: September 2005

In a study of the effect of experience on multidimensional auditory signal perception. 12 SONAR-trained and 12 untrained listeners identified 5 physically similar dimensions (quality, inflection, duration, relative frequency, and source) of speech sounds and SONAR signals. Response time and accuracy measures were obtained. From these, a third measure (information rate) was derived. Results on all criterion measures support a hypothesis that perception is more dependent upon prior experience than upon physical properties of signals per se. A second hypothesis was also supported that suggested that identification difficulty of each of the five dimensions would be rank-ordered differently, both as a function of signal type and listener experience. Auxiliary findings included an apparent superiority of the right ear for listening to speech sounds and of the left ear for other kinds of sounds. Other results suggested that a short-term memory phenomenon was occurring.
Vibration of Resilient Isolators and Structures That Possess Viscoelasticity
Authors: Snowdon J. C.
Published: September 2005

The dynamic mechanical properties of rubberlike materials and plastics are reviewed briefly. The dynamic properties that would make a rubberlike material ideally suited for use as a resilient isolator are described. It is shown that the properties of a mechanical combination of low- and high-damping rubbers can approach these ideal properties more closely than the properties of either of the constituent rubbers. Consideration is given to wave effects that occur in resilient isolators at high frequencies. Results of calculations that describe the vibration of an internally damped Timoshenko beam are presented. In these calculations, damping is associated with both the bending and the shear strain of the beam material. The individual contributions of the bending and shear components of damping are made apparent. The vibration of internally damped Bernoulli-Euler beams is also considered. The beams are driven by two or three forces positioned such that the net force transmitted to the beam terminations is attenuated through significant ranges of frequency. The influence of secondary forces upon the driving-point impedance presented to a primary force at other locations on the beams is also discussed. [Work sponsored by U. S. Bureau of Weapons, U. S. Bureau of Ships, and U. S. Office of Naval Research.]
Multiple-Band Configurations for High Damping
Authors: Lazan B. J. , Sokol G. , Metherell A. F.
Published: September 2005

Conventional damping tapes consisting of a single band and a constrained layer of damping adhesive are shown to have limited damping. Although some improvement can be realized by utilizing multiple conventional bands and adhesive layers, this approach does not realize the full potential of the damping adhesives. Considerable improvement can be realized in a multiple-band configuration in which alternate bands are rigidly anchored on opposite sides of the configuration. The energy dissipation in such a configuration is analyzed considering both short (rigid) bands and long (elastic) bands. This analysis, presented in terms of parameters involving geometry and material properties, shows that much larger damping can be realized than in conventional damping tapes and other surface treatments. An experimental program for checking the validity of the theory is reviewed and data are presented. Design approaches are illustrated for surface treatments involving both uniaxial- and biaxial-stress applications.
Use of Plastic Models for Determining the Vibration Characteristics of Large Structures
Authors: Wright D. V.
Published: September 2005

The vibration-transmission characteristics of large structures have been investigated by means of tests on plastic models during studies of methods for reducing the amount of machinery vibration transmitted to the hulls of naval ships. Force and acceleration instrumentation suitable for the vibration testing of plastic models is described and the advantages of plastic as a model material pointed out. The sonic velocity and compressional loss factor of Plexiglas are given as functions of frequency. Vibration spectra measured on shaker-driven plastic models of some large steel structures are compared with similar data measured on the prototypes. The results show that the resonant frequencies, average vibration levels, and mode shapes of large structures are obtained quite accurately from tests on plastic models if the models are accurately scaled, but that the levels of the response peaks are only approximate. For accurate prediction of peaks, the material damping of the plastic must be equal to the effective frictional joint damping of the prototype. [Work supported by the Bureau of Ships, U. S. Navy.]
Infrasound from Geophysical Phenomena
Authors: Young Jessie M. , Greene Gary E.
Published: September 2005

Analysis of records from an array of microphones near Washington, D. C., has revealed frequent occurrence of low-amplitude traveling pressure waves in the atmosphere with periods greater than 1 sec. A systematic study of continuous recordings reveals a number of signal types, and some of them have been classified as to characteristics and/or origin. Signals arising from magnetic storms and aurora are compared and contrasted with waves apparently arising from tropospheric meteorological sources. Radiation from earth-sea-atmosphere coupling is discussed briefly and examples of several types are shown. Two large groups of acoustic waves are separated according to direction of arrival, even though the origin is not presently understood.
Internal-Pressure-Wave Phenomena and Troposphere Winds
Authors: Young Jessie M. , Bowman Howard S.
Published: September 2005

A group of long-period traveling pressure waves that show plane-wave properties with periods between about 4 and 15 min and speeds of 15–70 m/sec has been recorded on infrasonic microphone arrays in the Washington, D. C., area. The occurrence and characteristics of the waves are compared with properties and dynamic behavior of the troposphere, especially with winds and temperatures, in an attempt to understand the origin and propagation phenomena.
Ionospheric Motions Caused by Rayleigh Waves
Authors: Cook Richard K. , Baker Donald M.
Published: September 2005

Rayleigh waves of considerable amplitude from the Alaskan earthquake of March 1964 passed across the United States of America. The waves radiated sound into the atmosphere. The sound pressures measured at infrasonic stations at Boulder and Washington were about 20 dyn/cm2, corresponding to vertical surface motions of 12 cm/sec. The sound waves had periods of the order of 25 sec, and were radiated almost vertically upward. Waves starting upward with an amplitude of 12 cm/sec will increase to 104 cm/sec at an altitude of about 160 km. At higher altitudes, shock waves are formed, and the oscillatory vertical motions are estimated to be of the order of hundreds of meters/second. Observations of the ionospheric motions were made by sending radio waves almost vertically upward at Boulder, and measuring the Doppler-shifted waves reflected from the ionosphere back down to the ground. Doppler shifts, caused by sound from the Rayleigh waves, of more than 3 cps occurred for radio waves at 4 Mc/sec. These correspond to vertical motions of the ionosphere of more than 100 m/sec.
Periodic Interferometer for Measuring Relative Phase Velocity of Sound in Fluids
Authors: Moseley Donald S.
Published: September 2005

Sound of short wavelength (18 in. in water) is caused to travel a pathlength that is varied periodically. Velocity of phase propagation in the fluid is inversely proportional to the total phase difference over minimum and maximum pathlengths. With the aid of quadrature processing and phase comparison between sent and received signals, the total phase angle can be read from an oscilloscopic display, or converted by digital processing to a direct velocity readout.