bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Ultrasound on Permeability of Cell Membrane
Authors: Braungart Dale C.
Published: September 2005

Current research in this laboratory indicates that ultrasound, at the intensity and frequency employed, alters the permeability of cell membranes. Investigations were carried out, both in vivo and in vitro, in several biological systems, including various cancer cell lines. Findings indicated that ultrasound increased the uptake of labeled isotopes and other chemical agents. Furthermore, cancer chemotherapeutic studies indicated that in combination with certain drugs ultrasound apparently inhibited the growth of tumor cells, both solid and ascitic forms.
Physical Mechanisms for Biological Effects of Sound
Authors: Nyborg Wesley L. , Chuongvan C. , Claes H. P.
Published: September 2005

Understanding and control of sonic action on biological cells requires continued development of acoustical theory and of experimental procedures. Available nonlinear theory is helpful in explaining intracellular stresses, displacement, and circulations produced by sound; but the analysis must be generalized to deal with gellike media. When cellular envelopes are ruptured by sonic irradiation of cell suspensions, the destruction is usually ascribed to “cavitation,” whose role is not well understood. In recent experiments with red cells, bubble activity is controlled by degassing the suspension and then deliberately providing air in one or more “pockets” of suitable size. On studying effects of various parameters, it is found as in earlier work [Hughes and Nyborg (1960)] that cellular changes result at much smaller amplitudes than are required for such phenomena as sonoluminescence. These changes probably result from small-scale motions of and near the bubbles. Details of bubble-associated motions are being studied with low-frequency large-scale arrangements. [Work supported in part by the National Institutes of Health, U. S. Department of Health, Education, and Welfare.]
Changes in Behavior of Mosses Treated with Ultrasound
Authors: Dyer Hubert J.
Published: September 2005

Short, growing filaments of moss protonema [Physcomitrium turbinatum (Mx.) Bridel] develop readily on mineral agar into normal plants; they produce branch filaments by a regular pattern of lateral divisions of the subapical cells and extend themselves linearly by divisions of the apical cell. Divisions of intercalary cells that produce two in-line daughters in the main axis are quite rare, elongation of the axis being essentially restricted to the apical cell. Brief, low-amplitude, topically applied sonic vibration of subapical, individual cells in the filament frequently results in the division of the treated cell or one of its near or distant intercalary neighbors so as to produce in-line daughters. Persistent differences in growth pattern as compared to normal plants have been observed in several cultures of moss plants derived from single, treated, apical cells; they are described.
Transmission of Sound in a Moving Fluid
Authors: Hemond C. , Zadnik T.
Published: September 2005

A summary of work currently in progress at the University of Hartford Research Laboratory [under sponsorship of the U. S. Office of Naval Research] concerned with noise created by fluids moving through piping systems at various flow rates. The purposes of this project are to develop adequate test methods for determining the noise level within the pipe at any given point along the system and from analysis of test data to predict the behavior of both discrete and random input signals as they pass through the piping network. The signals under consideration here are low frequency in the range from 20 cps to 1 kc/sec. Discussion of problems involved include the selection of an input transducer capable of giving the desired performance (i.e., frequency response and signal strength) and the installation of the transducers and test equipment in the system. A brief indication is given of the results obtained thus far from the analysis of test data.
Aerodynamic Noise from Uncased Centrifugal Fan Rotors
Authors: Chanaud R. C.
Published: September 2005

The broad-band sound generated by rotation of small uncased centrifugal fan rotors with forward-curved blades was found to be described best in terms of randomly oriented dipole sources. The dependence of the over-all sound power on rotor size and speed did not agree precisely with the dependence predicted for a dipole source. The lack of agreement was determined to be a result of making measurements in the near field of the source. This conclusion can also explain why the empirical fan law for sound does not agree with the dependence predicted for a dipole source. A fixed edge placed near the rotor periphery (to simulate a cutoff) caused generation of sound at the blade-passage frequency. The directionality of the sound field and the dependence of the tone sound pressure on rotor speed was exactly as predicted for a dipole source. Quadrupole radiation, due to fluctuating fluid stresses, appeared to be negligible.
Research towards a High-Efficiency Voice-Communication System
Authors: Olson Harry F. , Belar H. , Rogers Edward S.
Published: September 2005

A speech analyzer and synthesizer with a capacity of 200 speech elements has been developed with the objective of evaluating the performance. The speech analyzer consisting of normalizers, syllable and syblet segmenters, sound recognizers, sequencers, and memories converts the speech elements into a code. The speech synthesizer converts the code to speech by reproducing prerecorded speech elements. The advantages of the voice-communication system employing the analyzer and synthesizer are the high intelligibility and the low transmission rate of only 23 bit/sec.
Performance Evaluation of the Vocal-Response Synthesizer
Authors: Voiers William D. , Smith Caldwell P.
Published: September 2005

The vocal-response synthesizer was evaluated from the standpoint of speech intelligibility, speech quality, and speaker recognizability by tests that included the diagnostic rhyme test, the Fairbanks rhyme test, and a specially developed test of speaker recognizability. Synthesized speech was also evaluated after being successively processed from two to four times by the vocal-response synthesizer. Comparative data for a conventional vocoder and a voice-excited vocoder were also obtained. [The research reported in this paper was sponsored by the U. S. Air Force Cambridge Research Laboratories, Office of Aerospace Research.]
Middle-Ear Movement in Anesthetized Cats
Authors: Peake William T. , Guinan John J.
Published: September 2005

Amplitude and phase measurements of ossicular motion were made from 20 to ∼15 000 cps. The middle-ear transfer function obtained in this way can be corrected for changes introduced by opening the bulla and bony septum. The stapes appears to move very much like a piston for stimulus intensities below 140 dB. No appreciable articulation of the incudo-stapedial joint was observed for stimuli in the linear range, although the data indicate significant articulation of the malleo-incudo joint at high frequencies. [This work was supported in part by the Joint Services Electronics Program; in part by the National Science Foundation; by the National Institutes of Health, Public Health Service, U. S. Department of Health, Education, and Welfare; the National Aeronautics and Space Administration.]
Acoustics of the Civic Centre Theatre, San Diego, California
Authors: Purcell Jack B. C. , Wetherill Ewart A.
Published: September 2005

The new Civic Theatre for the city of San Diego forms part of the new Civic Centre complex, which also includes a 10 000-seat convention hall and a high-rise city-administration building. The Theatre has an audience capacity of 3000, with seating arranged on a main floor and two balconies. The auditorium is designed to accommodate the variety of speech and music activities that normally comprise the program requirements for large multipurpose civic theatres. It has a volume of approximately 860 000 ft3 and a design reverberation time (for full occupancy) of 1.7 sec at the midfrequencies. An integral aspect of the acoustical design is the demountable stage enclosure required for orchestral concerts. The paper compares the predicted reverberation time for the auditorium with measurements obtained following completion of the building. Tests prior to opening were conducted with full concert orchestra for purposes of obtaining optimum performance characteristics. A discussion of these tests and some observations on multifunction use are included in this paper. Architects for the project are Rosser, Kennedy, & Ruocco of San Diego, California.
Acoustical Design of the Los Angeles Pavilion
Authors: Veneklasen Paul S. , Knudsen V. O. , Leonard R. W. , Christoff Jerry P.
Published: September 2005

The acoustical design stressed a balance between clarity, envelopment, and reverberance. Both acoustical and optical modeling were used to verify the design advice given to the architects. The hall is multipurpose, wide fanshaped, seats 3250 persons. A versatile, movable, orchestra enclosure is used to convert to an orchestra hall and the stage is terraced to optimize sound projection and orchestral balance. Classical music does not need electroacoustic sound reinforcement; however, it was stressed that reinforcement would be required for light opera and stage plays. The absorption versus frequency of the auditorium seats was specified. Elaborate precautions were taken to exclude city noises and noise from mechanical and plumbing equipment. A permanent, but movable, acoustical canopy projects outward from the proscenium arch to enhance clarity. The side-wall shapes are designed to promote early sideward reflections for envelopment. The reverberation time is adjustable between nominal values of 1.6–2.5 sec. Performers approve the playing ease and musicians and critics comment favorably, with reservations that emphasize the challenges of the future.
Acoustical Spectroscopy Using Optical Masers
Authors: Stoicheff Boris
Published: September 2005

The paper discusses laser techniques for the optical measurement of the absorption and propagation velocity of hypersonic waves.
Survey of Auditory Discrimination Abilities of Unpracticed Subjects
Authors: Riach W. D. , Trahiotis Constantine
Published: September 2005

400 normal-hearing high-school students drawn from Metropolitan Detroit were administered a battery of discrimination tests. The battery consisted of 5 pure-tone (1000-cps) tests and 1 speech-discrimination test. The parameters of the pure-tone stimulus investigated were frequency (monotic and dichotic). intensity (monotic and dichotic), and duration (monotic only). For each of the pure-tone tests, difference thresholds were obtained using a 2-alternative forced-choice procedure. The speech-discrimination test was presented at various V/N ratios and percentage correct scores recorded. These normative data are compared to previous studies that have utilized well-trained subjects. Additionally, multiple regression and factor analyses were carried out on these normative data and the results are discussed. [Work supported by the National Institutes of Health, U. S. Department of Health, Education, and Welfare.]
Effects of Stimulus Presentation Rate upon Intelligibility-Test Scores
Authors: Cohen Marion F.
Published: September 2005

There is a need standardization of intelligibility testing as it is used for evaluating communications systems. The purpose of this experiment was to evaluate the effects of different rates of stimulus presentation upon intelligibility scores. Stimulus materials provided by the Fairbanks rhyme test and the diagnostic rhyme test were recorded several times with various time intervals between words. They were presented to listening crews under two different conditions: (1) bandpassed from 200 to 4000 cps; (2) processed by an 18-channel vocoder. The data for each condition were analyzed to determine the effects of the various stimulus rates upon both the intelligibility scores and the standard error reliability of these scores. [The research reported in this paper was sponsored in part by the U. S. Air Force Cambridge Research Laboratories, Office of Aerospace Research.]
Propagation of Stress Waves in Linear Viscoelastic Solids
Authors: Kolsky H.
Published: September 2005

A number of problems associated with the propagation and reflection of stress pulses in linear viscoelastic solids are discussed. The correlation between experimental observations and theoretical predictions for specimens of various plastics are considered and computational methods for predicting the changes in pulse shape that result from the dispersion and attenuation produced by viscoelastic solids are described. The changes in pulse shape that take place when a mechanical pulse is reflected at the boundary between two viscoelastic solids is also considered. It is shown that under some conditions a pulse of compression may produce an s-shaped reflected pulse, part of which is tensile and part of which is compressive. Some recent work on the propagation of dilatational pulses in blocks of plastics is also described, and it is shown that this work throws considerable light on the viscoelastic losses associated with volume changes in these materials. Finally, a brief discussion of wave propagation under conditions where linearity no longer obtains is included.
Characteristics of Sound Propagation in an Isothermal Atmosphere with Constant Winds
Authors: Pierce Allan D.
Published: September 2005

A dispersion relation for low-frequency disturbances in an isothermal atmosphere is derived that relates the three components of the wave-propagation vector k to the angular frequency ω and that depends on the sound speed, the wind velocity v, and the acceleration of gravity. The relation is obtainable from that for propagation without winds if ω is replaced by ω−k⋅v. It is shown that the cross section of the surface in k space taken perpendicular to the kx, axis are conic sections, and a nomograph is produced that enables one to predict qualitatively the topology of the surface. The topology is classified on the basis of wind Mach number and frequency. Parametric equations are derived for the surfaces of equal arrival time and the topology of these surfaces is interpreted by use of the nomograph. The theory predicts the existence of a wind-wave mode, which tends to travel at approximately the wind speed and which has wavelengths in the wind direction of the order of 2πυ/ω. The author believes that the wind-wave mode may afford an explanation of the noise that is regularly detected by microbarograph arrays and that is minimized by noise-reducing lines of pipe.
Improving Headphone Listening Comfort
Authors: Bauer B. B.
Published: September 2005

The fatigue resulting from prolonged listening to a headphone appears to be related to the in-phase motion of earphone diaphragms that cause the sound to be localized in a single frontal spot within the head, this being entirely unlike what is experienced in the normal listening mode. Out-of-phase connection for some people shifts the sound spot toward the back of the head, but without any apparent effect on comfort or intelligibility in the presence of noise [J. Acoust. Soc. Am. 33, 851(A) (1961)]. By analogy with previous loudspeaker listening experiments [IEEE Trans. Audio 11, 88–92 (1963)], the following experiment was performed: A speech signal was split into two equal 90° out-of-phase channels and connected to earphones through a crosscoupling network that restores normal interaural delays. The resulting sound is completely spread within the head. eliminating the oppressive feeling of the usual headphone listening. The effect is demonstrated at the meeting.
High-Speed Sound Spectrograph
Authors: Prestigiacomo A. J.
Published: September 2005

A new sound spectrograph is described that incorporates several automatic features facilitating operation and permitting higher analyzing speed. The mechanical assembly includes a tape-handling system for continuous record and playback with flutter below 0.15% and frequency response within ±1 dB from 50 to 12 000 cps. An integral part of the mechanical assembly is a tape scanner and marking drum. The scanner will repeatedly scan any 2.4-sec segment of tape for spectrographic analysis and the tape may be automatically advanced for continuous-signal analysis. A high speed-up ratio enables a spectrogram to be made in 80 sec. Three basic types of spectrograms may be made with either uniform frequency equalization or a special speech equalizer: the normal display of time vs frequency with intensity shown as blackness, an amplitude contour display, and cross-sectional amplitude spectra. Analyzing filter bandwidths of 50 and 300 cps are used with optimal frequency and transient responses. Either a linear or logarithmic frequency scale may be selected and an internal calibrator will automatically mark the frequency scale on each spectrogram. The marking stylus assembly has been designed to provide automatic engagement and pressure adjustment.
Variations in Spoken-Digit Duration in a Restricted Environment
Authors: Li Kung-Pu , Chapman W. D.
Published: September 2005

The purpose of this study was to observe the natural duration of the 10 digits 0 through 9 spoken in a restricted environment. The utterances consisted of digit strings, 1, 2, and 3 words in length, separated by tone bursts presented to the speaker at 1.5-sec intervals to maintain the continuity of each utterance. Each of the 10 digits was placed in every possible environment with relation to adjacent digits and silence. Oscillograms of 850 such utterances from 5 speakers were made which displayed the log of the signal amplitude in 3 separate frequency bands, the linear amplitude scale, the log amplitude scale, and the pitch function. Word and phoneme boundaries were established from these oscillograms by a set of rules, which are described. The durations were then measured and correlated with the position of the word or phoneme in the digit string, the phonemic environment of the word, and its internal phonemic structure. A set of rules is proposed that may be used to describe the duration of a digit in such an environment.
Numerical Calculation of Sound Radiation from a Vibrating Surface of Revolution
Authors: Grosso Marie , Chertock George
Published: September 2005

The method described earlier [J. Acoust. Soc. Am. 36, 1305–1313 (1964)] has been used for a variety of radiation problems and improved in precision and range of usefulness. The present program will calculate the near- or far-field radiation from any surface of revolution on which the normal vibration velocity is specified in the form υ=υ0Ψ(x)cos(mφ)cos(ωt−δ(x)), where Ψ(x) is an arbitrary function of the longitudinal position x, m is an arbitrary integer, φ, is the longitude, ω is an arbitrary circular frequency, and δ(x) is an arbitrary phase. The solution is based on a numerical solution of the von Helmholtz integral equation for the pressure at the surface. Numerical results are given for sound radiation by ring pistons on a spheroid [cf., Hanish, NRL Rep. 6108 (July 1964)]; pulsations of a finite cylinder [cf., Williams et al., J. Acoust. Soc. Am. 36, 2316–2322 (1964)], and circular pistons on a sphere [cf., Chen and Schweikert, J. Acoust. Soc. Am. 35, 1626–1632 (1963); and P. M. Morse Vibration and Sound, p. 325].
Effect of Dipolar Forces between Molecules on Ultrasonic Relaxation caused by Rotational Isomerism
Authors: Piercy J. E. , Rao M. G. Sheshagiri
Published: September 2005

Much of the information concerning rotational isomers that has been drawn from ultrasonic measurements in the liquid state is suspect, owing mainly to the uncertain effects of dipolar forces between molecules. The ultrasonic relaxation in 1, 1, 2 trichloroethane, which should be particularly susceptible to dipolar interaction, has therefore been studied in solvents of differing dielectric behavior. The absorption and velocity of solutions of 1, 2, 2 trichloroethane in heptane, chlorobenzene, and acetone has been measured at frequencies of 7, 16, 24, and 45 Mc/sec over the temperature range −40° to +90°C. The activation energy is found to be approximately independent of solvent, and therefore should be a measure of the barrier to internal rotation in the isolated molecule. However, the apparent difference in energy between isomers depends in a more complicated fashion on their environment. The molecular origin of these phenomena is discussed.
Sloshing of a Liquid in Connected Cylindrical Tanks Owing to U-Tube Free Oscillations
Authors: Yeh Gordon C. K.
Published: September 2005

When two parallel cylindrical tanks are connected by a pipe joining the tank bottom, the liquid can oscillate back and forth between tanks, just as in a U-shaped tube. This paper deals with the axisymmetric sloshing oscillations excited in each tank because of the flow back and forth between the tanks. By applying the results from a recent paper, “Liquid Sloshing due to a Time Dependent Discontinuous Boundary” [P. G. Bhuta and G. C. K. Yeh, Intern. J. Mech. Sci. 7 (1965)], the expressions of velocity, pressure, and waveheight are obtained in terms of the liquid density, tank dimensions, pipe radius, and U-tube natural frequency, which, in turn, is a function of the tank dimensions, pipe dimensions, and the magnitude of acceleration vector. Resonance will occur whenever the U-tube natural frequency is equal to any one value of the natural frequencies for the axisymmetric sloshing modes of the liquid in each cylindrical tank. Pertinent dimensions to be avoided are pointed out. Extension of the results to asymmetric sloshing based upon a recent report on “Liquid Sloshing in a Moving Tank with a Time Dependent Discontinuous Boundary” [G. C. K. Yeh, TRW Space Technol. Labs. EM 14-12 (June 1964); Proc. Midwestern Mechs. Conf. 9th, Univ. Wise. 1965 (to be published)] is also indicated.
Turbulent Wall Jet as a Broad-Band Shaker
Authors: Lyon Richard H. , Gordon Colin
Published: September 2005

A turbulent jet impinging on an elastic structure can be a convenient source of broad-band mechanical excitation. Recent experimental and theoretical studies of the mechanical power absorbed by a thin plate from a turbulent “wall jet” are described. It is found that the proportional band levels are fairly constant below a “cutoff frequency.” This frequency is determined by the pipe diameter and volume flow. At higher frequencies, the excitation drops markedly. The cutoff frequency determines the environmental-frequency régime that a wall jet will simulate. Lower cutoff frequencies require higher volume flows and larger pipes. For these reasons, the wall jet may be more useful in simulating noise environments in the upper and middle audio range, but may be of lesser value at lower frequencies. [Work supported by the U. S. Air Force.]
Mobility Characteristics of Idealized Machines having an Arbitrary Number of Mounting Points
Authors: Parsons Jerome S.
Published: September 2005

In estimating file effectiveness of a multimount isolation system, it is necessary to know the mobility or impedance characteristics of the machine, the mounts, and the foundation structure. As a first step in the study of estimating mount effectiveness, this paper considers the mobility characteristics of a machine idealized as a rigid body of simple geometrical shape having an arbitrary number of mounting points. Equations are presented for calculating the point and transfer mobilities at the mounting points of such idealized machines. Mobility measurements on a steel rectangular parallelopiped (an idealized model of a machine with approximately a block shape) of dimensions ratio 3×5×7 are compared with theoretical values. Several recommendations are made relevant to mobility-coefficient calculation and to the problem of mount-effectiveness estimation.
Voiceprint Classification
Authors: Kersta L. G.
Published: September 2005

A binary-code automated classification system has been devised for voiceprints. The 10-digit code that enables 210 possible different codes per word resulted in unique speaker selection of better than 96% for a population of 12 speakers. When the classification is based serially on 5 cue words, the selection accuracy was better than 99.5%. The classification system is based upon the uniqueness of a selected amplitude-quantized frequency vs time matrix.
Linear Modeling of Long Underwater Acoustic Paths
Authors: Walker W. F.
Published: September 2005

The effective treatment of signal-transmission problems requires an analytical representation or “model” of the signal path. Long underwater acoustic signal paths fall into the class of randomly time-varying dispersive channels, which show approximate linearity and short-term statistical stationarity. A mathematical model for such paths is proposed that is based on the statistical behavior of the time-varying impulse response h(ητ). This model has sufficient generality to account for the fluctuating dispersive characteristics of underwater paths and their property of increasing attenuation with frequency. Certain constraints may be included, however, so as to provide the model with a high level of mathematical manageability. The effects of the channel model on the transmission of white noise, stationary random signals, and CW signals are treated. The detailed treatment is confined to the point-to-point transmission situation, although some discussion is presented on the more complicated problem of multiple-input/multiple-output channels, including interior reflective and refractive bodies.
Stability of Propagated Sound I
Authors: Parvulescu Antares , Clay C. S.
Published: September 2005

We have compared (a) signals propagated between fixed transducers at different times and (b) signals between transducers in slightly different geometries at slightly different times. Such comparison is best performed as a crosscorrelation; we used the method of matched signals (M.E.S.S. Processing) to obtain analog correlations in real time. The experiment was performed in January 1962 in the Tongue of the Ocean with a separation of about 20 nm; a radio link permitted a closed-loop experiment. The results show extremely reproducible propagation. The entire collection of arrivals contained up to 20 dB more coherently reproducible energy than the strongest arrival taken alone. The correlation coefficient was stable for many minutes, and the observed decay can be ascribed to ship motion. We estimated the horizontal correlation distances to be about 50–100 wavelengths; the vertical extent of this region is less than 1 wavelength. These three dimensions are mutually consistent, and also consistent with a simple model of the propagation. The vertical correlation distance can post facto explain an observed periodic variation in correlation coefficient as due to ship pitching. [Hudson Laboratories, Columbia University Informal Doc. No. 74. Work supported by the U. S. Office of Naval Research.]
Digital Spectral Analysis of Audio Signals
Authors: Doty K. L.
Published: September 2005

Digital spectral analysis offers certain advantages over analog techniques: (1) the equivalent bandwidth of the analysis can be varied easily and (2) complicated calibration procedures are not required. A real-time analog-to-digital magnetic-tape recording system, designed as part of future instrumentation that will record digitized noise or speech signals and calculate their spectra with special purpose computer, records 31 250 digitized analog time samples per second in a 9-bit code. Currently, an IBM-7094 data-processing system is programmed to perform trapezoidal integration of the Fourier integral to obtain the spectrum of the digital recordings. The Fourier transform of a 16-msec square pulse differed from the calculated values by less than 4% of the actual amplitudes in the frequency range 0–5000 cps. A comparison was made between the digital spectra obtained for several speech sounds and those obtained with 50-cps constant-bandwidth analog filters. Within expected limits, the agreement was good. The time required for the IBM-7094 computer analysis and plotting program to process a single pitch period of the vowel “a,” sustained at 125 cps, is 15 sec.
New Method for the Rapid Determination of Speech Frequencies
Authors: Partridge Gordon R.
Published: September 2005

A new approach has been taken to the problem of rapid determination of the nature of sounds. The times between successive cycles of speech or other signals are measured, and the reciprocals of these time intervals are displayed on a storage oscilloscope. This results in an almost instantaneous presentation of frequency as a function of time, the readout of information lagging the acquisition of data by just a single cycle (a cycle is two successive zero crossings for purposes of this paper). A separate portion of the storage screen displays amplitude versus time. The patterns produced by the instrument look very similar to those of “visible speech” generated by other methods such as comb filters. Ultrasonic as well as audible frequencies are covered, up to 100 kHz. In these higher frequencies, the instrument has been used for the examination of bat and porpoise sounds.
Capacity of the Acoustic Channel as a Medium for Communication
Authors: Rowlands R. O. , Quinn F. G.
Published: September 2005

This paper is concerned mainly with the calculation of the optimum frequency band for communicating through the acoustic medium, as a function of range, when certain other parameters that affect the signal-to-noise ratio are specified. The capacity of the channel, which serves as an upper bound on the rate at which information may be transmitted through the channel, is also calculated.
Technique for the Analysis of Musical-Instrument Tones
Authors: Freedman M. David
Published: September 2005

A technique that can be used to analyze the transient part of a musical tone has been developed. The analysis can be carried out on a high-speed digital computer, the signals being presented to the computer through an analog-digital converter. The analysis procedure consists of four steps: (1) the determination of an adequate mathematical specification for an equation to represent the sound-pressure-wave generated by a musical instrument; (2) the determination of the constants in the equation for a given tone (No assumption is made regarding the frequencies of the partial tones. Inharmonic partials are detected and accounted for in the specification function.); (3) the verification of the results, both mathematically and by resynthesis of the tone (using a digital-analog converter), to check the adequacy of the representation (the former technique yields a more sensitive measure of the error.); (4) iterating, if necessary, to improve the results. At this stage, the original specification function may be altered, if necessary. Using this technique, reasonable success has been achieved in analyzing and resynthesizing tones.
Pitch Quantizing for Computer Music
Authors: Mathews M. V. , Miller Joan E.
Published: September 2005

A program is described that quantizes the frequencies of a series of computer-generated notes. The program can be instructed to adjust the frequencies so as to fall on a given scale or so as to fall at specified intervals from the frequencies of another voice. Various combined requirements on quantizing levels may be constructed using the logical operations of “and” and “or.” For example, the allowable intervals for voice three may be a third or a fifth from voice one and a fifth from voice two. The program has been used to generate and compare melodies that have no scale; that have specified harmonic intervals between voices, but no melodic scale; that have 12-tone melodic scales and specified harmonic intervals between voices; and that have diatonic scales with specified harmonic intervals between voices. The program has also been used to generalize harmonization based on the conventional tonic, subdominant, and dominant chords from diatonic melodies to 12-tone melodies and to melodies with continuous scales.
Experience in the United Kingdom on the Effects of Sonic Bangs
Authors: Warren C. H. E.
Published: September 2005

Over the past five years, a number of exercises involving the making of bangs have been staged in the United Kingdom. The bangs have been made both by flying aircraft at supersonic speeds and by firing explosive charges. From this work, information has been obtained on the intensities and waveforms of aircraft sonic bangs as measured out of doors in the open at ground level, on the nature of the disturbances that are recorded inside buildings, and on the subjective reactions of people to these bangs. The paper summarizes the results of this work.
Optimally Synthesizable Boundedness and Stability of the Limit Domain for Response of General Lumped Systems
Authors: Skowronski J. M. , Liu R. W.
Published: September 2005

In this paper, an interpretation is proposed concerning the kinetic-synthesis idea for mechanical systems with application to their stability problems. We consider a lumped mechanical system with n degrees of freedom, suitably generally modeled, everywhere nonlinear according to interconnections, with positive and partially negative damping, and with the input having ultimately limited power. The determination of a model that must be optimal for realizing the required aims of the structure is called that structural synthesis of the mechanical system. The part of this synthesis, which is the optimal choice of mentioned characteristics in form and in the values of describing parameters, is called kinetic synthesis. The procedure lies in the definition of a synthesizing function, which is a function of the change of characteristics inside some class, called the range of synthesizability, also to be defined, by some property required for response. The possibility of choice of the optimal characteristics for given property is shown and the sufficient criteria are defined. so the optimal case of boundedness and stability of limit domain may be solved without solving the response equations.
Effects of Transecting the Brachium of the Inferior Colliculus upon Auditory Cortex Potentials Elicited by Clicks
Authors: Strominger Norman L. , Nieder Philip C.
Published: September 2005

Using pentobarbital anesthesia, four cats were prepared as follows: (a) auditory cortex was exposed bilaterally and surveyed for evoked potentials; (b) attempts were made to section the acoustic brachia; (c) multiple chronic electrodes were implanted in auditory cortex. Two months elapsed between steps (b) and (c) in a single animal. Step (c) preceded (b) in another animal. Multiple attempts were made to record evoked potentials in unanesthetized and pentobarbital anesthetized animals. Following electrophysiological tests, cats were anesthetized and perfused. Electrode positions were confirmed. Brain stems were prepared for histological study. The brachium was sectioned completely on one or both sides in five of the six cats. Evoked potentials with onset latencies less than 10 msec never were obtained ipsilateral to complete brachium lesions, but were recorded in unanesthetized and anesthetized animals ipsilateral to incomplete lesions. These data suggest that at least the partial integrity of the brachium, or perhaps closely adjacent fiber systems, is necessary for preservation of short latency potentials in auditory cortex elicited by clicks.
MIMI Multipath Measurements
Authors: Birdsall T. G.
Published: September 2005

Measurements of underwater acoustic paths important for 420-Hz propagation in the Straits of Florida have been made using pseudorandom coding. The propagation is from Fowey Rocks near Miami, to phones off Bimini Island, Bahamas, about 43 miles. The transmission employs modulation of a 420-Hz continuous carrier by phase coding each segment of 8 cycles. The reception is recorded with a phase reference, and is computer-processed by crosscorrelation with the phase code. The key features in the processing are phase-coherent demodulation, 10-bit amplitude conversion, crosscorrelation shift step of 1/210 sec, and integration times of 1.2–288 sec. Each integration yields the average complex path gain (amplitude and phase) at each of the correlation step delays. Specific results from February 1965 tests show that the path structure is amazingly phase coherent. Comparison of successive 18-sec receptions over 5 min indicate a frequency shift less than 0.5-Hz. This matches MIMI CW results. [Work conducted by The Universities of Michigan and Miami, and supported by the U. S. Office of Naval Research Acoustics Programs (Code 468).]
Propagation of Acoustic Energy in a Time-Varying Inhomogeneous Medium
Authors: Bakhru K. , Berman A.
Published: September 2005

In order to study the propagation of acoustic energy in a time-varying inhomogeneous medium, such as the ocean, a mathematical model has been proposed and simulated on a digital computer. Basically, the ocean is represented by piecewise continuous-velocity profiles that can have certain random variations about a mean profile. The random variations in the properties of the medium are generated by Monte Carlo methods. Under ray theoretical approximations, the medium behaves as a Markov chain. This model appears capable of predicting the statistics of the observed variations in travel time, depth, arrival angle, and fading as a function of distance between the source and the receiver. [Hudson Laboratories of Columbia University Informal Documentation No. 83. Work supported by the U. S. Office of Naval Research.]
Separating and Timing Overlapping Sofar Signals
Authors: Mayall Miles , Graves T. A.
Published: September 2005

In multiple solar signaling over long distances, where the solar wavetrain is a few seconds in duration, the problem of a large signal obscuring the cutoff of another smaller signal may occur. This paper describes a method of separating the two signals for timing purposes. The frequency spectrum of an underwater explosion signal displays a line structure caused by interference between the shock wave and the first bubble pulse. At 32, 52, 72,⋯, of the bubble-pulse frequency, the shock wave and first bubble-pulse wave are 180° out of phase and sharp nulls in the explosion frequency spectrum result. Since the bubble-pulse frequency is determined by the size and depth of the explosion, two sofar depth charges of different weights will produce signals with different null frequencies. By passing the overlapping signals through a narrow bandpass filter set at the null frequency of the larger signal, the smaller obscured signal will be enhanced as much as 12 dB, relative to the larger signal and the obscured sofar cutoff may be timed with an accuracy of 50 msec.
Ambient-Sea-Noise Correlation
Authors: Arase Elizabeth M. , Arase T.
Published: September 2005

Measurements of the space-time crosscorrelation of ambient sea noise were made with pairs of hydrophones, separated vertically between 2–40 ft, at a depth of 14 500 ft, in the frequency range from 100 to 1200 cps. Previous results at sea state 5 [J. Acoust. Soc. Am. 38, 146–148(L) (1965)] were extended and now include lower sea states. The crosscorrelations for six frequency bands are given as a function of hydrophone separation and are compared with results by other experimenters. The time delay corresponding to the maximum value of the space-time correlation is given as a function of the separation, and the slope of these lines is shown to increase with frequency. [Hudson Laboratories of Columbia University Informal Documentation No. 84. Work supported by the U. S. Office of Naval Research.]
Experimental Noise Studies of Inlet Guide Vane-Rotor-Stator Interactions for a Single-Stage Axial-Flow Compressor
Authors: Crigler J. L. , Copeland W. L.
Published: September 2005

Farfield noise-radiation patterns for the rotor alone, the inlet guide vane and rotor, the rotor and downstream stator vanes, and the inlet guide vane-rotor-stator combination are compared for a constant rotor speed and mass flow. For the configurations studied, the radiated-noise levels due to the interactions of rotor and downstream stator vanes are appreciably less than those clue to inlet guide vane and rotor interactions. It has been possible to correlate variations in the noise levels, with a knowledge of local conditions in the vicinity of the blades.
Rotational Noise of Helicopter Rotors
Authors: King Robert , Schlegel Ronald G.
Published: September 2005

An analysis procedure has been developed to predict propeller rotational noise during nonuniform, as well as uniform, inflow conditions. Although many studies have been conducted since the development of Gutin's equations (NACA TM I195), none have been developed that adequately describe the near and far rotational-noise fields of a helicopter rotor during forward-flight and maneuver conditions, where the rotor blades experience azimuthal pressure variations. This report presents a newly developed analysis that is an extension of the methods of Garrick and Watkins (NACA Rept. 1198). It removes many of the limitations of previous theory as applied to helicopter-rotor rotational noise. The rotor system is represented by a surface of stationary dipole radiators that simulate the normal pressure distribution on the rotor disk. The analysis utilizes blade-section loading, either measured or predicted, which contains both steady and varying components at integral multiples of the main-rotor rotational speed as a function of radius and azimuth. The analysis has yielded good correlation with measured helicopter-noise levels for various forward-speed and transient conditions. [Study partially supported under U. S. Aviation Materiel Laboratories Contract.]
Variability in Bone-Conduction Thresholds
Authors: Wilber Laura Ann , Goodhill Victor
Published: September 2005

Two studies were undertaken to isolate some potential sources of variability in bone-conduction thresholds. In the first study, 26 normal-hearing students were tested via air conduction and bone conduction at 5 octave frequencies: 250, 500, 1000, 2000, and 4000 cps. Bone-conduction thresholds were obtained using (1) 30 dB effective masking in the contralateral ear; (2) no masking and contralateral ear open; and (3) no masking but contralateral ear occluded. In the second study, 12 normal-hearing students were tested via air conduction and bone conduction at 6 frequencies: 250, 500, 1000, 2000, 3000, and 4000 cps. Bone-conduction testing was done using three different bone vibrators on each subject. In addition, thresholds for one of the vibrators were obtained using (1) white-noise masking in the contralateral ear; (2) narrow-band masking through an earphone in the contralateral ear; and (3) narrow-band masking through an insert receiver in the contralateral ear. The results of these studies indicated that, although test-retest thresholds under a given condition were close, differences in thresholds were present, depending on the type of masking and the particular vibrator being used. This was true even after differences in ac thresholds and in the output of the vibrators as measured by an artificial mastoid were taken into account.
Bone-Conduction Threshold Measurements
Authors: Smith E. L. , Bowman Howard S. , Weissler P. G. , Cook Richard K.
Published: September 2005

Monaural forehead bone-conduction threshold measurements have been made using bone-air cancellation to eliminate the contralateral ear instead of masking noise. The results obtained compare favorably with previous bone-conduction threshold determinations made at NBS. Comparisons of bone and air-sensation levels at cancellation indicate the possibility of using bone-air cancellation as a calibration procedure for bone vibrators.
Random-Vibration Testing with Multiple Exciters and Control Transducers
Authors: Curtis Allen J. , Abstein Henry T.
Published: September 2005

Principles of random-vibration excitation and test-level control at one or more locations of substantial test objects are described. The effects of any correlation between excitations determine test levels and test-level control employing the mean spectral density of several transducer signals. The relationship of this mean spectral density to the spectral density of the mean, on an instantaneous basis, of the several control signals is developed theoretically for independent and for correlated signals. Experimental confirmation is demonstrated by analog computer. Artificial decorrelation of transducer signals employing the stack spacing between record and reproduce heads of a tape recorder is employed to obtain the power-averaged spectral density for test-level control. Testing philosophy and equipment considerations depend on knowledge of the correlation characteristics of the environment to be simulated. Selection of practical, economically feasible test methods that simulate environmental effects rather than the environment is presented. Application of test-level control using averaged and power-averaged transducer signals during three-shaker excitation of Surveyor spacecraft is presented.
Prediction of System Reliability under Random Loading
Authors: Smits Talivaldis I. , Lambert R. F.
Published: September 2005

In reliability prediction of vibrating systems under random loading, an analytical expression for the probability density of system-failure time is much desired. An approximate method of estimating this function is here suggested, based on system-response “peak” (i.e., crest, extremal, or rise) statistics, assuming a failure mechanism that involves a combination of cumulative fatigue damage and ultimate load failure. Earlier studies, by other investigators modeling total damage as a cumulative renewal process, are here extended, inter alia, to certain non-Gaussian processes. The appropriate response "peak" exceedance probabilities are fitted conservatively by standard distributions, and are converted into exceedance probabilities of incremental damage per cycle via N-S curves. Thus, reliability distributions are calculated for a certain linear system excited by various stationary non-Gaussian and Gaussian noise processes, and are compared. The need for simplification of reliability calculations and for avoiding extensive numerical integration is emphasized. [Work supported by the U.S. Air Force.]
Acoustical Properties of a Free-Edge Bender Disk under Radiation Loading
Authors: Potter D. S. , McLennan M. W.
Published: September 2005

The vibration of thin disks in a vacuum under various boundary conditions has been extensively treated. Lax, in 1944, analyzed the effect of radiation loading on a clamped-edge vibrating disk. This present paper extends this analysis to arbitrary edge conditions. The technique is to employ the set of orthonormal functions appropriate to the given boundary conditions in vacuo to describe the radiation loading of the disk. The differential equation may be solved simultaneously for the complex coefficients of the expansion either for forced vibrations at a given frequency or for free vibrations in a given mode, solving additionally for the new resonant frequency. The extreme case of free-edge conditions was evaluated in detail. Using a digital computer, numerical values were obtained for the resulting generalized radiation impedances between modes, the complex expansion coefficients, and such quantities as pressure distribution, beam pattern, radiated power, and mechanical Q. [Work supported in part under subcontract to ITT Federal Laboratories, Nutley, N. J., under contract to the U. S. Naval Underwater Ordnance Station, Newport, R. I.]
Phonon-Phonon Interactions at Ultrasonic Frequencies
Authors: Rollins Fred R.
Published: September 2005

In this paper, some recent experiments are described that illustrate the nonlinear interaction of longitudinal and transverse elastic waves in isotropic solids. Both classical and quantum theories of phonon-phonon interaction are discussed, and correspondence between the two is developed. Experimental results are shown to be in relatively good agreement with theoretical predictions.