bluuebunny/crossref_metadata_2025 huggingface dataset:
Subjective Judgment of Loudness Level of Impulsive Noises for the International Round Robin Tests
Authors: Thompson P. O. , Gales R. S.
Published: October 2005

Loudness matches of short (1 sec or less) samples of impulsive noise versus similar short samples of 1-kHz sinusoid or third-octave noise band were made by 13 subjects using the method of adjustment. Each of 21 different impulsive noises and the 1-kHz reference sound were reproduced via loudspeaker from the magnetic tape furnished all participants in the round-robin test. Loudness balances for each noise were replicated five times for each of three loudness levels (approximately 75, 55, and 95 phons) for each subject. Intersubject variability in the equal-loudness judgment was great, the σ being roughly three times the intrasubject σ. Variability was similar for 75- and 55-dB levels and less for 95-dB presentation. Results on the following will be discussed: (1) loudness level of noise as related to frequency spectrum, amplitude-time characteristics, and presentation level, (2) experimental versus calculated loudness level, (3) loudness level of tone pulses versus duration, and (4) hearing acuity and other characteristics of the 21 potential and 13 finishing test subjects. [This work was in cooperation with the round robin evaluation project arranged by ISO/TC43/SCI/SGB.]
Comparative Loudness of Highpass Filtered Speech
Authors: Thomas Ian B. , Kelly Coleman J. , Ohley William J.
Published: October 2005

Frequently we encounter speech which has been passed through systems having poor low-frequency response. While the missing low frequencies do not greatly affect intelligibility, it is possible that they heavily influence the perceived loudness. Thus the present experiment was designed to compare the loudness of highpass filtered speech with that of unmodified speech and to determine if the subjective loudness of filtered speech corresponds closely to any instrumental objective measure of intensity. Subjects heard either modified or unmodified speech by operating a manual switch. They were instructed to match the loudness of the two types of speech. Results are expressed in terms of the number of decibels of gain necessary to raise the perceived loudness of filtered speech to that of unmodified speech. This number of decibels increases to 6 dB for a cutoff of 1000 Hz and is 14 dB at 1600 Hz. Results obtained by comparing the intensity of both types of speech on a true rms meter agree very closely with the subjective values. [Work supported by NIH.]
Noise and Vibration of Chain Saws
Authors: Brammer A. J. , Olsen N. , Piercy J. E. , Toole F. E.
Published: October 2005

Experiments have been performed to assess the risks, to professional chainsaw operators, of permanent hearing loss and of traumatic vasospastic disease (TVD) resulting from exposure to excessive vibration (Raynaud's disease). A chain saw, which a survey of machinery noise on logging operations revealed to be typical (see preceding abstract), was mounted on a dynamometer without its bar or chain. Eliminating exhaust and intake noise reduced the level at the operator's ear by 24 dBA from the open exhaust configuration when the saw was mounted on the dynamometer, and by at least 18 dBA when cutting wood. The exposure to noise of several operators during normal logging operations was measured as a function of time and found to be greater than that permitted by either the Walsh-Healey or CHABA criteria. Effective exhaust and intake mufflers would remedy this situation. The vibration of the handles was examined when sawing hard and soft woods, and the levels obtained for two chain saws of convention construction were similar and in excess of European criteria for the onset of TVD. A third saw that possessed shock-mounted handles generated acceptable vibration levels.
Effect of Rotor Blade Leading Edge Serrations on Fan Noise
Authors: Gray L.
Published: October 2005

Noise measured from a fan with conventional rotor blading for configurations both with and without a fan shroud plus inlet is compared with similar data for a fan with rotor blade leading edge serrations. Using the conventional fan as a reference, the test data show (1) an increase in high-frequency noise due to the serration pattern for both the shrouded and shroudless configuration, and (2) an increase in low- to middle-frequency range noise for the shroudless configuration. Possible causes for the noise increases are discussed based on results obtained from the configurations tested and on current theories in available literature.
Estimation of Noise Generated by EHV Transmission Lines
Authors: Teplitzky Allan M.
Published: October 2005

Previous investigations have shown that the audible noise generated by an EHV transmission line increases when exposed to adverse environmental conditions. The frequency spectrum of the noise is composed of tones at the even harmonics of 60 Hz and broad-band noise in the mid- to high-frequency region. Utilities are interested in predicting noise levels at the boundary of the right-of-way in order to design electric power transmission lines that minimize noise intrusion into neighboring communities. This paper presents a procedure for estimating the noise generated by an EHV transmission line subjected to rain based upon laboratory studies of small lengths of conductor and compares the results to measured field data.
Energy Distribution in Pipe/Fluid Systems
Authors: White Pritchard H.
Published: October 2005

Effective noise control in a pipe/fluid system can be achieved only if the major energy path is known. When the majority of energy is in the fluid, an in-line silencer is appropriate, whereas when the pipe wall carries the energy structural isolation or damping is proper. A scheme to predict the energy distribution has been developed. At low frequencies (below the ring or acoustic cutoff), the distribution is strongly affected by the method of excitation. A gas-filled pipe driven acoustically will retain most of the energy in the gas, whereas a liquid-filled pipe may transfer the energy into the pipe wall. At high frequencies, statistical energy concepts may be used to predict the energy distribution. In this case, the distribution becomes proportional to the modal density ratio, regardless of the excitation. Experiments on air- and water-filled steel and polyvinyl chloride pipes tend to verify the theory.
Acoustical Treatment of a Multipurpose Elementary School Gymnasium
Authors: Gatley William S.
Published: October 2005

Design and evaluation of absorbing structures for a multipurpose gymnasium with a volume of 45 000 ft3 are described. The room had a stage at one end, a hardwood playing floor, painted cement block walls, and a steel roof. Reverberation times in excess of 4 sec were measured in the untreated room. As a result, speech and music programs were unintelligible, and noise levels during sporting events (volleyball and basketball) were excessive. Low-frequency absorbing structures able to withstand impacts from stray balls were designed and installed. Suspended ceiling units constructed from mineral fiber panels are described. Functional and acoustical performances of the treated room are analyzed and costs of the treatment are summarized.
Scale Studies o! Reverberation in Large Coupled Spaces
Authors: Shankland R. S.
Published: October 2005

Reverberation times over a wide frequency range have been measured in St. Peter's Basilica in Rome and in St. Mary Queen of the Earth Cathedral in Montreal. The latter is built to a linear half-scale of St. Peter's in its basic architecture which makes possible important comparisons with acoustical theory. However, the decorations, especially the sculpture, are much less extensive in the Montreal church, and furthermore, St. Peter's has more side chapels with openings to act as sound absorbers and coupled air volumes. As a consequence the reverberation times do not scale in the simple ratio as originally anticipated, for the midfrequency reverberation time in St. Peter's is 7.1 sec while that in the Montreal church is 5.9 sec. However, a comparative analysis of the data is important for understanding the influence of coupled air volumes on reverberation and the propagation of sound in large rooms of complex shape. The results are consistent with those previously reported for the four Patriarchal Basilicas in Rome and with measurements in other large churches.
Open Plan: Calculation versus Field Evaluation and Measurement
Authors: Hyde Jerald R.
Published: October 2005

Previous papers [P.S. Veneklasen and J. R. Hyde, J. Acoust. Soc. Amer. 47, 78(A) (1970)] have discussed the results of model studies of the open plan which have yielded information such as barrier efficiency, attenuation due to distance and treatment, source orientation, and space planning for a specific open plan layout. These results are used to help predict the “acceptability” of such an environment for its intended use, along with articulation index calculations and assumptions of ambient background noise conditions. The end result comes in the form of recommendations to the architect. Here we compare our model studies, calculations, assumptions, and anticipated subjective response with results measured and observed in the full-scale final product. Conscious acoustical design is shown to be imperative. In addition, less quantitative concepts are discussed, such as distraction and the need for the individual to understand the acoustical limitations of the open space in which he performs his work. Results are given for both open plan offices and schools.
Rating System for Evaluating the Acoustical Environment of Existing School Facilities
Authors: Walsh David P.
Published: October 2005

Recent work on architectural acoustics has been directed primarily towards new school facilities. However, a serious problem facing all major school districts is keeping existing facilities usable. In most instances school districts have not developed an effective, systematic approach to school renovation or plant repair. As a step towards solving this problem the Computerized Facilities Inventory (CFI) program was developed and implemented in the San Francisco Unified School District (SFUSD). The CFI program, performed on all pre-1933 schools in the district, recorded the physical characteristics of each individual space, such as architectural, lighting, heating, acoustical, etc. This information, together with unit costing data for corrective work, was programmed into the SFUSD's accounting computers. In the development of the acoustical portion of the study it was decided that the time and instrumentation necessary to obtain objective data for each space would be prohibitively expensive and would yield a higher degree of accuracy than could be used. Therefore a subjective rating system was developed which is closely related to the standard objective units of acoustic measure and whose implementation relies on experienced individuals in the field of architectural acoustics.
Acoustical and Theatrical Aspects of Orchestra Enclosure Design
Authors: Paoletti Dennis A. , Auerbach S. Leonard , Kirkegaard R. Lawrence
Published: October 2005

An orchestra enclosure functions as an extension of auditorium walls and ceiling to couple the stage and auditorium into one acoustical chamber for concerts and other musical performances. The size and configuration of the enclosure are derived from over-all acoustical consideration and also the scale and visual quality of the auditorium. In addition, consideration during design must be given to lighting, rigging, and operational requirements, as well as construction techniques, storage, and cost. This paper reviews a variety of recent orchestra enclosure designs. Examples of different enclosure types are illustrated, acoustical objectives are discussed, and areas requiring additional study and analysis are mentioned.
Directional Exploration of Two Reverberant Sound Fields
Authors: Pirn Rein , Boys Teddy D.
Published: October 2005

The reverberant sound fields of two comparably sized but acoustically dissimilar halls (recital hall and theatre) were excited by means of a steady-state random noise source, located on stage. Using a specially constructed directional microphone with known directivity, octave-band sound-pressure measurements were made near the center of each audience area. A total of nine directions, covering the hemisphere of exposure to the sound field, were explored in each hall. It is shown that the loudness disparity between the two halls, which stands in good agreement with the measured reverberation times, is attributable to nonfrontal sound only. Typically, the level of nonfrontal sound in the theatre was found to be 4 dB below the level of nonfrontal sound in the recital hall, while frontal sound levels in the two halls were essentially equal. The measurement data are discussed with reference to subjective impressions of acoustical “envelopment.”
Equivalence of Source or Receiver Averaging for One-Third Octave Bands of Random Noise at Low Frequencies in a Reverberant Room
Authors: Ingalls Douglas J.
Published: October 2005

An experiment was performed in which the SPL was measured in one-third octave bands from 100 to 315 Hz for the Hg reference sound source at 9 source positions×6 receiver positions×3 replicates for each combination of source/receiver positions. Source positions in a 10 600-ft3 reverberant room were at 3-ft intervals within a 6 ft×6 ft floor area with nearfield reflectors employed to avoid impedance changes due to the walls. Receiver positions were selected to avoid direct field and boundary effects. Each replicate was measured using a 32-sec integration time for determination of the time average of the SPL. The mean and variance of source positions is the same as the mean and variance of receiver positions implying the source and receiver obey an equivalence principle for bands of random noise. Hence, adequate spatial averaging of pressure squared at one source position in a reverberant room can lead to an accurate determination of free-field sound power output for broad-band sources. The experimental variances agree at low frequencies with 1/BT [H. S. Kurtovic, Ann. Telecomm. 16, 254 (1961) and D. Lubman, J. Acoust. Soc. Amer. 44, 1491 (1968)], where B is the noise bandwidth and T is the reverberation time. The observed variances are, however, lower at high frequencies.
Traversing Microphone Spectra: A New Technique for Analysis of Room Acoustics
Authors: Lubman David
Published: October 2005

A small microphone traversing the sound field in a room will encounter spatial variations of sound pressure. Residing in the time statistics of the microphone signal is information about the space statistics of the sound field—information which may be found from a spectral analysis of the microphone signal. For example, the theoretical traversing microphone spectrmn for an ideal diffuse sound field consisting of a single pure-tone component is derived. An indication of the degree of steady-state diffuseness in a room is found by comparing the quickly measured traversing microphone spectrum with this ideal.
Infrasonic Disturbances in the Ionosphere from Severe Thunderstorms
Authors: Davies Kenneth , Jones J. E.
Published: October 2005

In the spring and summer of 1970, a network of spaced Doppler sounders was operated in Oklahoma. Several ionospheric wavelike disturbances (period 3–5 min) were observed associated with severe weather such as the Oklahoma City tornado of 29–30 April 1970. From the three-dimensional propagation vector in the ionosphere the acoustic wave is traced back to its source using a model atmosphere. In conjunction with radar weather data it is possible to locate the thunderstorm which is the likely source. Spectral analysis of the disturbances reveal peaks of energy near 3.5 and 4.5 min.
Spectral Analysis of Infrasound in the Atmosphere
Authors: Bedard A. J. , Bowman H. S.
Published: October 2005

In the past a number of sources of atmospheric infrasonic signals have been identified. Some of these sources are distinguished by means of the observed frequency spectra. The spectra for several different signal types are presented and the differences discussed. Spectra for signals related to severe storms, earthquakes, ocean waves, and geomagnetic activity are shown. Also, data for other types of signals are presented.
3D Ray Tracing for Acoustic-Gravity Waves
Authors: Georges T. M.
Published: October 2005

A new computer program uses Hamilton's canonical equations to calculate and display acoustic-gravity ray paths in atmospheres with three-dimensional wind and temperature variability, including earth curvature. Some interesting ray geometries arise, for example, when acoustic rays pass through cyclonic wind fields and for gravity waves in windy atmospheres. These and other examples are used to illustrate the workings and capabilities of the program.
Observations of Atmospheric Waves in the Planetary Boundary Layer
Authors: Hooke W. H. , Young J. M. , Beran D. W.
Published: October 2005

Observations of atmospheric waves in the planetary boundary layer made by an acoustic sounder and by a microbarograph array are presented and compared. The two techniques are complementary in that the sounder provides a detailed picture of temporal changes in the structure of the bottom 1000 m of the earth's atmosphere, while the microbarograph array provides horizontal wave phase speed and direction. In addition, the sounder can utilize Doppler information to determine atmospheric velocities while the microbarographs measure pressure fluctuations. Results are compared with standard meteorological data and with wave theory, and directions for future research are indicated.
Elastic Surface Waves on Surface-Strengthened Glasses
Authors: Bucaro Joseph A. , Davis Charles M.
Published: October 2005

Phase velocities of surface elastic waves on surface-treated glasses have been measured over the frequency range 3–30 MHz. The surface waves were launched by means of a solid wedge and were subsequently detected by means of a laser probe. Since these inhomogeneous waves are confined to a surface layer approximtaely one wavelength thick, these frequencies probe regions from 100 to 1000μ. The glass sample treatments included both thermal quenching and ion-exchange. A substantial dispersion was measured indicating that such a technique should be very useful for the determination of stress profiles in treated glasses.
Bottom Baffle Effect
Authors: Polak J. A.
Published: October 2005

The sea floor constitutes, for a bottomed or near-bottomed receiver, an enormous baffle which under some circumstances can significantly modify the response of the receiver. The extent of these modifications are illustrated by means of idealized bottom models. It is shown that the magnitude of the response modification depends sensitively on the angle of incidence. The implications of these results for measurements employing bottomed and near bottomed receivers are discussed.
Diffraction Theory for Acoustic Scattering at the Ocean Surface
Authors: Holford R. L.
Published: October 2005

Previous treatments of the scattering of sound at a rough ocean surface have dealt with cases where the surface irregularities are either much larger or much smaller than the acoustic wavelength. A phenomenological treatment is presented for the important practical case when the two are comparable. In this approach, a complex ocean surface is considered to be decomposed into an angular spectrum of periodic traveling-waves, each of which acts as a moving diffraction grating that scatters the incident energy into certain characteristic directions (the diffraction orders) with associated Doppler shifts which are harmonics of the surface-wave frequency. The scattering from any one such traveling wave is obtained by the novel application of a Lorentz-type transformation, reducing the problem to one of a stationary grating. The results are found to be consistent with those of a laboratory experiment due to Liebermann [J. Acoust. Soc. Amer. 35, 932 (L) (1963)] for a one-dimensionally rough surface, and the implications for scattering from a wind-driven sea surface are discussed. [Work supported by the Office of Naval Research under contract.]
Problem of Localization in the Median Plane
Authors: Gardner Mark B. , Gardner Robert S.
Published: October 2005

In the absence of level and reverberation clues the distance of an inanimate or recorded source is almost completely nebulous. Associated with this is the commonly observed front-back confusion of sources in the median plane. So strong is the resulting illusion in some cases, that even a visible dead-ahead source cannot be made to appear “out-in-front” unless deliberate head movements are resorted to. The resulting effective horizontal displacements of the source introduce level and time differences at the two ears. These two important clues for localization in the horizontal and transverse planes are absent for sources located strictly in the median plane. Such limitations, together with the more difficult utilization of head movements, the presence of certain localization anomalies, etc., will be considered in relation to the problem of localization in the median plane.
Interaural Time j.n.d.s for Acoustic Transients
Authors: Haftner Ervin R. , De Maio Joseph
Published: October 2005

Interaural time j.n.d.s for low-frequency tonal stimuli are little affected by large temporal displacements from the midline [Herschkowitz and Durlack, J. Acoust. Soc. Amer. 46, 1964 (1969)]. This seeming inconsistency with Weber's law may be due to redundancy in the temporal properties of sinusoidal waveforms, which in turn reduces variance in interaural timing. In order to test this concept, we measured the effects of large delays on the time j.n.d.s for auditory clicks. Baseline delays ranged from 0 to 500 μsec. The stimuli were moderate intensity, 100–2000 Hz bandpass (BP) and 3000–4000 Hz BP clicks. The j.n.d.s showed an approximately linear increase with the baseline offset, with those at 500-μsec delay being as much as three times those at 0 μsec.
Effects of the Center Frequencies of One-Third Octave Bands of Noise of the Detectability of Intensity-Produced Lateralization Shifts
Authors: De l'Aune W. R. , Elfner L. F.
Published: October 2005

A signal-detection rating paradigm was employed to assess the detectability of an intensity produced lateral shift in a binaurally fused auditory image. Five center frequencies (0.5, 1.0, 2.0, 4.0, and 8.0 kHz) were employed to investigate the possibility of an inverse monotonic relationship between detectability and frequency of the pure tone stimulus as reported by De l'Aune and Elfnet (1970) occurring in a narrow-band noise situation. The stimulus consisted of a 1-sec, 40-dB HL centered image (the standard) followed 200 msec later by a test image which was either a centered image or a shifted image. The image was shifted by adding 1 dB to one ear and subtracting 1 dB from the opposite ear. The subjects were required to rate their certainty on a four-point scale as to whether a shift had occurred or not. It was found that the detectability scores were higher for the one-third octave bands than they were for pure tones of the same center frequencies in the frequency range from 2.0 to 8.0 kHz. A slight increase in detectability with increase in center frequency was noted.
High- and Low-Frequency Loudness Adaptation
Authors: Bray D. A. , Morgan D. E. , Dirks D. D.
Published: October 2005

Recent literature [Stockinger and Studebaker, (1968) and Petty, Fraser, and Elliott (1970)] contradicts much of the preexisting data concerning the magnitude and time course of suprathreshold loudness adaptation. A detailed study was undertaken to determine the magnitude of suprathreshold adaptation at 500 and 3000 Hz in six normal-hearing subjects. A controlled period of preadaptation was followed by 7 min of a continuous adapting signal of 70 dB SPL in one ear. The adapting tone was then continued an additional 4 min while a pulsed tone, identical to the pre-adapting conditions (3000 msec, 331/3% duty cycle, 10 msec rise-decay time) was introduced into the comparison ear for perstimulatory dichotic loudness balances. The experimental conditions were (1) adapting tone: 500 Hz; comparison tone: 400 or 3000 Hz; (2) adapting tone: 3000 Hz; comparison tone: 500 or 2000 Hz. Under these heterophonic conditions, adaptation was measured by the method of constant stimuli and repeated with a linear tracking technique. Essentially no adaptation was found at 500 Hz with either test method. At 3000 Hz a minimal decrement in loudness level (less than 5 dB) was obtained. The findings of minimal adaptation at 300 Hz and no adaptation at 500 Hz support the more recent literature indicating little, if any, loudness adaptation when binaural interaction is reduced or eliminated by a heterophonic procedure.
Digital Hardware Realization of a Random-Number Generator
Authors: Perry J. L. , Schafer R. W. , Rabiner L. R.
Published: October 2005

Random numbers are used in speech synthesis and psychoacoustic experiments. A digital random number generator that provides both uniform and Gaussian numbers has been constructed in TTL digital hardware and operates as a peripheral device on a Honeywell DDP-516 computer. For generating Gaussian numbers, the hardware operates approximately 700 times faster than an equivalent software generator. Generation of the uniformly distributed numbers is based on an algorithm described by Rader, Rabiner, and Schafer, BSTJ, November 1970. Ganasian numbera are generated by summing N uniform numbers, where N is specified by the user and is in the range 1⩽N⩽214. The number generator was evaluated using a chi-square test, and correlation functions and resulting power spectra of the output were measured. A general description of the hardware organization will be presented.
Noise Transmission in Corridors and through Open Doorways
Authors: Davies Huw G.
Published: October 2005

Simple expressions are obtained for the transmission and reflection of sound at corridor junctions. The results are applied to the transmission of sound from corridors into rooms through open and partially open doorways. Experimental studies support the theoretical results. Comparisons are made of sound transmission from unlined corridors through walls with closed doors and from lined corridors through walls with open doors. Estimates can thus be obtained for the extent and quality of the absorption required in corridors for circumstances when it is normally convenient to keep intervening doors open.
People and Carpet: Acoustical Significance in One Church
Authors: Roller H. Stanley , Boys Teddy D. , Kirkegaard R. Lawrence
Published: October 2005

In a church of typical rectangular plan and modified “A”-shaped cross section, acoustical data were taken with the main aisle and chancel carpeted and later with gypsum board covering the carpet. The measurements were made with the sanctuary occupied and unoccupied. The acoustical parameters compared are reverberation time, loudness, and articulation index. The study indicates that the absorption coefficients normally used for an audience and the published coefficients for carpets are not valid for rooms with this general configuration.
Sound Absorption of Draperies Revisited
Authors: Kirkegaard R. Lawrence , Siekman William
Published: October 2005

Measurements were made of the acoustical absorption characteristics of various configurations of draperies in the PAL reverberation room. Configurations included variable weight, flow resistance, fullness, airspace, and flameproofing treatment. Results of these measurements will be presented and compared with similar small-scale measurements reported by Batchelder, Thayer, and Schultz [J. Acoust. Sec. Amer. 42, 573–575 (1967)].
Simplified Procedure for Correlating Absorption Coefficient to the Complex Acoustic Impedance of Lining Materials
Authors: Jhaveri Arun G.
Published: October 2005

Because of the real concern for environmental noise pollution, more and more acoustical materials are being developed and used for noise control purposes. There are lengthy and complicated design procedures available for correlating parameters that govern acoustical efficiencies. The present paper attempts to simplify the interrelationship between such lining parameters as sound absorption coefficient, real and imaginary components of complex acoustic impedance, as a function of frequency. These correlations are shown through equations, curves, and nomegraphs for direct read-out and engineering applications.
“Interference Pattern Method” of Measuring Sound Reflection from Uneven Surfaces
Authors: Ando Yoichi , Suzumura Yukio , Maekawa Zyun-iti
Published: October 2005

In previous works [Y. Ando, Electron. Commun. (Japan) 51, 10–18 (1968) and, partially, Y. Ando, J. Acoust. Soc. Amer. 45, 1563(L) (1969)] the complex reflection coefficients from even surfaces were accurately measured by this method, considering directivity and acoustic center of the transducers and excluding sphericity error and effect of diffraction by finite dimension of test materials. The reflection of sound from uneven walls has been a problem of interest in architectural acoustics for some time. It is shown that the method is also useful in the scattered near boundary field under certain conditions. Measurements were performed on a semicylindrical boss on rigid plane, a periodically uneven surface of rectangular profile, and a louver array obliquely covered on an absorbing material. Tests were made as a function of distance from reflecting point and angle of incidence. Measured values of the first two cases were compared with those calculated values. Agreements between them were satisfactory for the lower frequency range. In the last case, measured values were greatly dependent on the sign of incident angle, though no theoretical analysis has been attempted.
Auroral Audibility
Authors: Silverman S. M. , Tuas T. F.
Published: October 2005

A comprehensive compilation of reports on auroral sounds ranging from the 16th century to the present have been made. The reports have been evaluated for their accuracy and catalogued according to their locations which range from 55° to 70° geomagnetic latitude. A detailed study showed that significant correlation exists between sunspot cycles, magnetic character figures, and the reports of auroral sound. The duration, quality, and possibly accompanying effects such as odor have been carefully examined. In determining a theoretical explanation, we have considered the psychological effect, tinnitus, meteorological effect, direct transmission, infrasonic waves, emission of radio waves in the audio region, direct perception of electromagnetic radiation, and electric field pressure effect. In considering the direct conversion of electrical energy to sound energy through electrostriction we considered two models, an isothermal and an adiabatic model. Calculations from these models showed that the electric fields are insufficient for producing audible sounds. Our final conclusion is that a fraction of the most intense auroras have associated electric fields which produce induced fields at ground level and that these induced fields in dry, calm weather lead to brush discharges which are audible.
Propagation of Noise in a Polytropic Atmosphere
Authors: Stuff Roland
Published: October 2005

An analytical solution of the wave equation of the polytropic atmosphere is found. It has been used by the author in a previous paper as initial solution for the sonic boom in a polytropic atmosphere [Conf. Sonic Boom, 3rd (1970) (to be published in NASA SP)]. The solution is valid beyond the scope of geometrical acoustics. It can be applied as initial solution instead of the solution for the homogeneous atmosphere, as for example in the theory of scattering or absorption of noise. An example is given by applying it to the theory of acoustical monopoles, dipoles, and quadrupoles.
Propagation Speed and Attenuation Coefficient for Plane Coherent Acoustic Waves in a Turbulent Medium
Authors: Wenzel A. R.
Published: October 2005

The results of numerical calculations of the propagation speed and attenuation coefficient for plane coherent acoustic waves propagating in a turbulent medium, based on equations derived previously, are presented. Two special cases are considered: waves in a fluid at rest, and waves in isentropic, irrotational flow. In each case the random inhomogeneities of the fluid medium are assumed to be statistically isotropic, and are assumed to have an exponential correlation function. The results for both cases indicate that the propagation speed of the coherent wave is less than the average sound speed of the medium; also that the attenuation coefficient increases, whereas the propagation speed decreases, with increasing wave frequency. The results obtained for waves propagating in motionless seawater (@15°C, 1 atm, 35‰ salinity) are compared with corresponding results obtained by basing the analysis on the scalar wave equation. It is concluded that, in underwater acoustics, basing the analysis of the coherent wave in a quiescent medium on the scalar wave equation, or stochastic Helmholtz equation, generally yields accurate results for the attenuation coefficient, but may lead to considerable error in the calculation of the propagation speed.
Comparison of Standard Methods of Calculating the Attenuation of Sound in Air with Laboratory Measurements
Authors: Piercy J. E.
Published: October 2005

The laboratory measurements of Evans and Bazley, Pohlmann, Harris, and Tempest and Harris were first chosen from all those available in the literature for the attenuation of sound in air. They form an authoritative international consensus. The attenuation was then calculated using the fundamental method of Kneser as well as the empirical methods of Harris and Committee A-21 of the Society of Automotive Engineers. Comparison of calculated and measured values show gross deviations in going from method to method, and from all methods to measurement, in some part of the range of frequency, humidity, and temperature of interest to problems of community noise. An extension of the fundamental method of Kneser to include the vibrational relaxation of nitrogen as well as oxygen is found to be in good agreement with the measurements. Directions of research to improve these methods are recommended.
Seismic Noise in Borehole Strain-Rate Meters Due to Infrasound
Authors: Dorman Leroy M. , Sacks I. Selwyn , Evertson Dale
Published: October 2005

An omnidirectional borehole volume strain-rate meter was concreted into a 412-in.-diam 150-ft-deep hole in competent rock. Noise (10−11 to 10−10 strain) related to atmospheric disturbances was observed in the period range 20 to 3000 sec. A microbarograph was buried nearby. The microbarograph and the strain rate meter both employ solion transducers. Visual observation of background on microbarograph and strain-rate meter records indicates high correlation between the two over a wide-period range. Coherence values computed indicate that S/N improvement up to 26 dB can be achieved by subtracting the microbarograph signal from the strain-rate-meter signal after suitable filtering. The latest experiments with vertical and areal strain-rate meters confirmed infrasound as the stimulus for the observed seismic noise. In addition, the areal data shows less short-period noise and thus provides better S/N for long-period surface waves. In order to achieve the best noise correction, a microbarograph must be used with spatial weighting proportional to the spatial sensitivity of the strain-rate meter to infrasound.
Atmospheric Absorption of Sound
Authors: Evans L. B. , Bass H. E. , Sutherland L. C.
Published: October 2005

By assuming air is composed of four gases, i.e., nitrogen, oxygen, water vapor, and carbon dioxide, and applying energy transfer rates for the binary collisions inherent in such a system, absorption of sound in the atmosphere has been predicted. The calculated curves based upon 24 energy transfer mechanisms are compared with experimental data over the humidity range of 0–100% relative humidity. Agreement between theory and experiment is good. By including classical absorption and rotational relaxation effects the total atmospheric absorption is also predicted. Calculations made for various concentrations of CO2 indicate that low-CO2 levels (less than 0.1% do not significantly affect absorption of audible sound at high humidities. At low humidities, however, CO2 is an important factor.
Relation of the Verbal Transformation and the Phonemic Restoration Effects
Authors: Obusek C. J. , Warren R. M.
Published: October 2005

The purpose of this investigation was to examine the relationship postulated between illusory changes of repeated words (“Verbal Transformations” or VTs) and illusory presence of phonemes replaced by noise (“Phonemic Restorations” or PhRs) [R. M. Warren and R. P. Warren, “Auditory Illusions and Confusions,” Sci. Amer. 223, 30–36 (1970)]. Separate groups of 20 subjects each were presented with one of four taped variations of the repeating stimulus word magistrate: (1) stimulus intact; (2) speech sound /s/ removed and replaced with 100-Hz octave band noise; (3) syllable “gis” removed and replaced with 100-Hz octave band noise; (4) speech sound/s/removed and replaced with a silent gap. When PhRs are evoked, most VTs involve the restored portion of the word, suggesting the usefulness of PhRs combined with verbal reorganizations in listening to speech in the presence of noise. Other effects of PhRs upon VTs were found. Implications of these results for mechanisms of speech perception are discussed.
Perceptual Confusions between Four-Dimensional Sounds
Authors: Webster J. C. , Woodhead M. M. , Carpenter A.
Published: October 2005

Are meaningless sounds learned and identified in a speech mode? Sixteen sounds were generated differing on four dimension, each having two values. These were: the source waveform contained either all harmonics or odd harmonics; the fundamental frequency was either 90 or 142 Hz; there were either one or two formant frequency regions; and the formant(s) was (were) either low, 600 (and 1550) Hz or high, 940 (and 2440) Hz. Twenty-four listeners identified these sounds. Fewer confusions were made between sounds (1) as the number of dimensions on which they differed increased, and (2) as the dimension(s) changed, from formant number to ferment frequency region, to fundamental frequency, to source waveform. Similarly, fewer confusions were made between sounds whose formant frequencies and fundamental frequency were in a fixed ratio than between those with the same formant frequency. In essence fixed ferment sounds were more often called the same sound than were fixed ratio sounds. The data fit a hypothesis that classification was made on a generalized “pitch” dimension.
Click Perception in Sentences as a Function of Mode of presentation and Handedness
Authors: Cyr D. , Daniloff R. , Berry R.
Published: October 2005

Eighteen right-handed and eighteen left-handed young normal listeners identified the location of clicks embedded within sentences. The sentence-click stimuli were presented monotically and dichotically to right and left ears; subjects wrote down click location with a slash mark on the sentence. Results indicate no significant difference in correct location of clicks (for either right- or left-handed listeners) as a function of mode of presentation, monotic or dichotic, to either ear, i.e., no laterality effect. Size of target (click on correct syllable, correct word, but not for word and/or word boundary) significantly affected correctness of location for right- and left-handed subjects. Left-handers were generally more accurate in over-all click location on word and syllable sized “targets.” There is also evidence of a handedness by mode of presentation interaction. Results are discussed in terms of models of speech perception and laterality-handedness effects.
Some Effects of Water Loading on Turbulence Induced Plate Vibration
Authors: Strawderman W. A. , Christman R. A.
Published: October 2005

This paper presents the results of a theoretical study of the effects of water loading on a turbulent-flow-excited, thin, finite plate. The water loading is defined as the pressure field produced in the water, at the plate surface, as a result of the plate vibration. The propagating component of this pressure field acts in temporal phase with plate resistive forces, and the nonpropagating component acts in phase with plate inertial forces. Thus, water loading may be interpreted as additional inertia and additional resistance of the plate. In an example, comparison of computed, turbulent-flow-excited water loaded and in-vacuo plate vibration spectra revealed the additional inertia to be 1.5–12 times the inertia of the plate alone. The additional resistance was found to be approximately 1% of the critical value of the in-vacuo plate. The additional inertial and resistive forces caused the “mode” shapes of the water-loaded plate to differ from the corresponding mode shapes of the in-vacuo plate.
Approximate Model for Predicting Operational Parameters of the Class IV Flextensional Underwater Transducer
Authors: Rutledge James R. , Royster L. H.
Published: October 2005

An approximate model for predicting operational parameters of the Class IV flextensional underwater transducer is developed. The model combines approximate solutions for the acoustic radiation problem, the forced shell vibration problem, and the electromechanical problem of the piezoelectric stack. The acoustic radiation is approximated by using a source density formulation technique and is coupled to a mathematical model which predicts the vibrations of the shell coupled to the piezoelectric stack. The forced vibration solution of the shell with the acoustical loads included is then combined with the electromechanical equations governing the piezoelectric stack. The model predicts operational parameters which includes the farfield radiation pattern and the stress variations and electrical impedance of the stack.
An Extension of the Bessel-Fubini Series for a Multiple Frequency Source of Finite Amplitude
Authors: Fenlon F. H.
Published: October 2005

A fundamental operational solution of lossless Burgers' equation is used as the basis for deriving the spectrum of a two-frequency finite-amplitude source within the critical range. The resulting expression is then generalized to the case of a multiple-frequency finite-amplitude source. The region of validity of these solutions is determined by specifying the critical ranges at which the waveforms become multivalued.
Acoustically Induced Optical Anisotropy under Bragg Conditions
Authors: Thompson T. B. , Klein W. R. , Riley W. A.
Published: October 2005

Solution of the Fraunhofer optical diffraction problem for pure liquids which exhibit induced birefringence at higher ultrasonic frequencies is given. Bragg diffraction is assumed. Experimental measurements are described for the temperature range 7°–30°C in ethyl cinnamate.
Temperature Dependence of Acoustically Induced Optical Anisotropy in Pure Liquids
Authors: Riley W. A. , Eck H. J.
Published: October 2005

The temperature variation of the optical anisotropy induced in several viscous liquids by acoustic waves was studied over a temperature range of approximately 270°–350°K. The results were obtained from performing a polarization analysis on the Fraunhofer optical diffraction pattern produced by the acoustic waves. Values of theoretical parameters defined from the theory of Peterlin for acoustically induced optical anisotropy in pure liquids were calculated from this data.
Sound Propagation in Rarefied Gases
Authors: Bauer H.-J. , Schotter R.
Published: October 2005

The various theoretical approaches to the problem of sound propagation in rarefied gases are sketched and categorized in light of whether or not they represent the experimental situation adequately: the transmission of a periodic additional velocity and the reception of a periodic pressure. The features of a new apparatus are described and preliminary results are presented.
Ultrasonic Studies in Binary Solutions with Pyridine
Authors: Thomas K. N. , Stumpf F. B.
Published: October 2005

The absorption coefficient and velocity of ultrasound at 19 MHz were studied as a function of concentration in binary solutions of pyridine with water, methanol, and ethanol. In addition, the compressibility and Rao's and Wada's constants were calculated and studied as a function of concentration. The measurements were made at 15°, 25°, and 35°C. An attempt was made to relate the concentration dependence of the absorption coefficient and the velocity to several reaction mechanisms—molecular association, deactivation of vibrational energy levels in pyridine, and perhaps others. In this attempt density, viscosity, and vapor pressure data from the literature were used along with the measured ultrasonic data.
Relaxation of Rotational-Isomeric Equilibria in Solutions of Polymethylmethacrylate
Authors: Bauer H.-J. , Immendörfer M.
Published: October 2005

Ultrasonic absorption from 1 to 30 MHz in solutions of PMMA in Dioxane at 15°, 25°, and 45°C established the existence of two distinct relaxation processes superimposed on the viscothermal and vibrational-relaxational absorption of the solution. Both Debye maxima show a reasonable temperature dependence: decrease of the relaxation strength and increase in the relaxation frequency with increasing temperature. That behavior can be explained by a relaxation of two independent rotational-isomeric equilibria within the polymer chain, caused by the temperature wave of the sound field [H.-J. Bauer, H. Hastier, and M. Immendörfer, Discussions Faraday Soc. 49, 238 (1970)] From the temperature dependence of relaxation frequency and strength, information can be gained about the rotational potential within the polymer chain; the variation of these parameters with tacticity allow an identification of the two processes to particular motions.
Elastic Moduli of Diamond and their Pressure Derivatives
Authors: McSkimin H. J. , Andreatch P. , Glynn P.
Published: October 2005

The adiabatic elastic stiffness moduli of a 22-carat type II diamond have been measured at 25.0°C by the ultrasonic technique described in IEEE Trans. Sonics Ultrasonics SU-5, 25 (1957). Basic wave velocities were obtained over a frequency range 20–500 MHz in order to minimize errors due to diffraction and coupling effects. Variations with hydrostatic pressure were measured at 20 MHz using a pulse superposition technique [J. Acoust. Soc. Amer. 41, 1052 (1967)]. Values of moduli in units of 1012 dyn/cm2 and their respective pressure derivatives (dc/dP) are as follows: c11 = 10.79±0.05; c12 = 1.24±0.05; c44 = 5.78±0.02, 5.98±0.7, 3.06±0.7, and 2.98±0.3.
Some Potential Uses and Limitations of Shallow Water Acoustic Theory
Authors: Ferris R. H.
Published: October 2005

Acoustic prediction in shallow water areas of the ocean must contend with a complex environment subject to a high degree of spatial and temporal variation. Calculations using highly idealized models are useful for obtaining certain generic characteristics of the acoustic fields, for example, the spatial distribution and duct excitation efficiency. The increasing potential of high-speed computers makes feasible the use of sophisticated models which can more closely approximate real ocean conditions. It has been demonstrated experimentally that a relatively simple normal-mode formulation can be used to calculate the field of a source in a shallow water area having uncomplicated geometry. Computer simulation has been used to obtain estimates of the expected effects of some environmental complications. Results have directed attention to a consideration of what acoustic phenomena are amenable to analytic calculations and the practicability of applying these models in the real ocean environment.