bluuebunny/crossref_metadata_2025 huggingface dataset:
Observations of Nonelastic Audiofrequency Resonances
Authors: Fitzgerald Edwin R.
Published: September 2005

Additional experimental evidence and analysis are presented that tend to confirm the fundamental nature of previously reported nonelastic audiofrequency modes or resonances in solids. The evidence cited includes some results recently advanced by others to demonstrate that the resonances arise from contact and/or apparatus effects, but these results really confirm the resonances as material properties. The particle-wave view of deformation is also strongly supported by these same, supposedly adverse, experimental results.
Wall Vibrations in Flue Organ Pipes and Their Effect on Tone
Authors: Backus John , Hundley T. C.
Published: September 2005

The question of the effect of wall vibrations on the tone of an organ flue pipe is examined theoretically and experimentally. The effect of nonrigid walls is calculated and it is shown that, if they do not affect the pipe frequency, they do not radiate appreciably. For pipes as ordinarily constructed of circular or nearly circular cross section, the lack of rigidity of the walls will have negligible effect. The wall vibrations actually occurring in sounding organ pipes were investigated experimentally and found to be owing to the vibrating air stream from the flue impinging on the lip. By artificially vibrating pipes to the same acceleration levels as when blown, it was found that the sound radiated from the vibrating walls is negligible. By surrounding pipes with a jacket and filling the space between with water, it was determined that the wall vibrations do not affect the internal standing wave in the pipe. Measurements of pipes in other organs confirmed the laboratory findings. It is concluded that the steady tones of organ pipes are not affected by wall vibrations.
Connection between the Fay and Fubini Solutions for Plane Sound Waves of Finite Amplitude
Authors: Blackstock David T.
Published: September 2005

Plane, progressive, periodic sound waves of finite amplitude are considered. The well-known solutions of Fay and Fubini are reviewed. At first glance, the two solutions seem contradictory, but, actually, each holds in a different region of the flow, the Fubini solution close to the source and the Fay solution rather far from the source. In the intermediate, or transition, region, neither solution is valid. A more general solution is obtained by using a method commonly employed for waves containing weak shocks. For distances up to the shock-formation point, the general solution reduces exactly to the Fubini solution. For distances greater than about 3.5 shock-formation lengths, the general solution is practically indistinguishable from the sawtooth solution, which, in turn, is the limiting form of Fay's solution for strong waves. The form of the general solution shows clearly how, in the transition region, the Fubini solution gives way to the sawtooth solution. The problem of an isolated cycle of an originally sinusoidal wave is also considered. Finally, some limitations on the weak-shock method are discussed. In the periodic-wave problem, the general solution is found to be inaccurate for distances greater than 1/α, approximately, where α is the small-signal absorption coefficient. In Appendix A, a brief extension of the analysis to spherical and cylinrical waves is given.
Auditory Intensity Perception and Neural Coding
Authors: Campbell Richard A.
Published: September 2005

Threshold signal-to masker ratios for three sinusoids (250, 1000, and 4000 Hz) presented in a masker of corresponding frequency set to various levels were gathered and are presented. The masker was either continuous or pulsed-on-only during both signal intervals. The block up-and down, two-interval, forced-choice psychophysical procedure was used. The relation between the obtained thresholds, and (1) the level of the masker, (2) whether the masker was continuous or pulsed, (3) other previously reported data for noise signals and maskers are especially considered. A discussion of these data as reflecting auditory nerve activity, loudness adaptation, increase of uncertainty and/or, a “drifting filter” is offered.
Binaural Masking of Speech by Periodically Modulated Noise
Authors: Carhart Raymond , Tillman Tom W. , Johnson Kenneth R.
Published: September 2005

The interference with intelligibility of monosyllabic words produced by continuous white noise, by modulated white noise, and by continuous speech (single talker) was studied during homophasic (N0S0) and antiphasic (NπS0) listening. Five signal-to-masker ratios, four modulation rates, and four magnitudes of modulation were used. Reception in the continuous noise was characterized by steeply sloping intelligibility functions and a 4.5-dB masking-level difference favoring antiphasic listening. Reception in modulated noise changed with the rate and depth of modulation. A 7-dB modulation yielded intelligibility functions highly comparable to those for continuous noise having the same average level. By contrast, more extreme modulation (14, 21 dB, and complete interruption) produced better intelligibility under both homophasic and antiphasic conditions than did continuous noise. This effect was particularly great when noise was completely interrupted either 4 or 20 times/sec, under which circumstances intelligibility remained above in 80% in a speech-to-noise ratio of −24 dB. The advantage of antiphasic over homophasic listening, or masking-level difference, was fairly similar for all conditions of modulated noise, averaging 3.9 dB. When the masking signal was a single competing talker, the antiphasic advantage dropped to 3.3 dB, and the intelligibility function did not duplicate any of the functions obtained in white noise, either continuous or modulated. Nonetheless, individual sets of conditions occurred where masking by speech and by modulated noise yielded equivalent performance, but the depth of modulation required for this equivalence varied with the speech-to-masker ratio being employed.
Superior-Olivary Response Patterns to Monaural and Binaural Clicks
Authors: Rupert Allen , Moushegian George , Whitcomb Milton A.
Published: September 2005

This study presents responses to dichotic clicks obtained from neurons of the medial superior-olivary nucleus of anesthetized cats. The neurons described in this study evidenced interactive patterns to both time and intensity differences by changes in their probabilities of response and by shifts in their latency. These findings suggest a complex synaptic organization of neurons, some of which are responsive to large and some to small interaural time differences. The former neurons that show interactions to large time differences (ca. 10.0 msec) respond consistently to both monaural left and right clicks. Binaural clicks, however, significantly decrease the probability of firing in response to stimulation of the lagging ear. Some of the latter neurons that show interactions to small time differences (ca. 0–2.0 msec) fire only once, while others discharge twice to a monaural click; these single and double responders exhibit changes in latency and probability of their firings upon binaural stimulation and, in the case of the double responders, alterations in both spikes occur upon appropriate stimulation.
Electrophysiological Analog of the Interaural Time-Intensity Trade
Authors: Worden Frederic G. , Marsh James T. , Bremner Frederick J.
Published: September 2005

Variations in the amplitude and polarity of evoked potentials with differences in intensity and arrival time of clicks delivered to the two ears were recorded from the superior-olivary nucleus in cats with chronically implanted electrodes. An analog of the “time-intensity” trade was seen in the cancellation of evoked potentials when time and intensity differences were opposed.
Measurements of the Scattering of Sound from Turbulence
Authors: Baerg William , Schwarz W. H.
Published: September 2005

An experiment was performed on the scattering of ultrasonic waves (25 65 kc/sec) from the turbulence produced by the flow through a grid in a 6×f-in. nozzle. The transmitter and receiver were of the solid dielectric, condenser type. The scattered signal was separated from the direct and reflected signals by a pulse technique. The intensity of scattered sound was measured at angles from 21.5° to 165° to obtain the differential scattering cross section. The 1-in. mesh grid was heated to obtain scattering from both the velocity and temperature fluctuations. The results were compared with the formulas derived by Lighthill, Kraichnan, and Batchelor. [Proc. Cambridge Phil. Soc. 49 531–551 (1953); J. Acoust. Soc. Am. 25, 1096–1104(1953); in Symposium on Naval Hydrodynamics, F. S. Sherman, Ed. (National Academy of Science-National Research Council, Washington, D.C., 1957), Publ. 515, pp. 409 430]. The general shapes of the curves predicted by the theory were obtained experimentally: the scattering was strongly in the forward angles, as was expected for high sound frequencies, with a minimum at 90°. The scattering from the velocity field displayed an additional minimum as 180° was approached, while the scalar field produced strong backscattering. Runs were taken at distances frown the grid to the center of the scattering volume of 5 and 22 in., and at Reynolds numbers of 4110–42 600, based on the grid mesh length.
Study of the Extraordinary Refraction of Elastic Waves in Calcite
Authors: Uttarwar S. R.
Published: September 2005

A general method for the study of elastic-ware propagation in anisotropic media is applied to the case of trigonal symmetry. A section of velocity surface for calcite is given. For elastic waves propagated in anisotropic media, the energy flux deviates from the direction of the wave normal. This prediction has been verified in the case of calcite. An optical method is used to observe the deviation of the quasilongitudinal ray from the wave normal.
Comments on “Detection of Random Acoustic Signals by Receivers with Distributed Elements: Optimum Receiver Structures for Normal Signal and Noise Fields” [David Middleton and Herbert L. Groginsky, J. Acoust. Soc. Am. 38, 727–737 (1965)]
Authors: Goode Burwell
Published: September 2005

A previous paper has shown an interesting structure for the optimum array-processing system using long observation time to detect weak stationary Gaussian signal in stationary Gaussian noise fields. For dominant amplifier and system noise (Case I discussed by Middleton and Groginsky), this structure is “factored.” The previous result is generalized to linear nonidentical hydrophones. A valid procedure for finding causal optimum filters is presented. The results are extended to the case or known signal; the optimum filters are not matched to the signal, but to a waveform dependent on signal, noise, and array structure.
Attenuation of Tortional Waves in Teflon
Authors: Leonard R. W.
Published: September 2005

This paper summarizes the results of rather extensive tests on the attenuation of shear waves in Teflon ®. The method used is described and the results of the measurements are presented. This technique is an extremely simple one requiring a minimum apparatus, and, in addition to yielding some fundamental data, makes a very nice student experiment in a teaching laboratory. The method and apparatus is not limited to Teflon, but can be used with lead or other materials that have a reasonable amount of damping. The method is not suitable for very high Q materials like aluminum or quartz.
Omnidirectional Scattering of Acoustic Waves from Rough Surfaces of Known Statistics
Authors: Moore R. K. , Parkins B. E.
Published: September 2005

The omnidirectional characteristics of the scattering of acoustic waves from statistically rough surfaces were experimentally investigated. The average differential scattering cross section was measured bistatically as a function of the angles of incidence and observation. Measurements for two surfaces of different roughnesses indicate the increase in the width of the scattering pattern's major lobe in the specular direction with increasing roughness. Scatter in directions other than near the specular (including the backscatter direction) is essentially independent of direction.
Extension of “Examination of Binaural Interaction”
Authors: Henderson Donald , Deatherage Bruce H. , Dolan Terrence R.
Published: September 2005

An apparent paradox involving the size of the necessary time difference between dichotic events for a midline auditory image is partially resolved by the fact that the initiation of a so-called timing signal in an ear is a function of the spectrum and intensity of the acoustic stimulus.
Relation of Air-Column Resonances to Sound Spectra Produced by Wind Instruments
Authors: Benade A. H.
Published: September 2005

Tonal spectra of wind instruments are sometimes estimated using passive-filter theory, or the principle of linear superposition. Experiments are described that illustrate the inadequacy of such calculations. Small changes in air-column frequencies and of the damping of these resonances can lead to large changes in the generated sound spectrum.
Miniature Transducer Assembly for Measuring the Properties of the Wall-Pressure Field in Turbulent Flows
Authors: Clinch J. Michael
Published: September 2005

The design of an assembly of miniature transducers for wall pressure measurements in turbulent boundary layer flows is described. It is believed that the transducers are the smallest that have been used for the detection of turbulent pressure fluctuations. Calibration of the transducers indicated a sensitivity of −130 dB re IV/μbar and a uniform frequency response from 10 cps to 20 Kc/Sec.
Reply to “Comments on ‘Harmonic Distortion of Spherical Sound Waves in Water’” [C. W. Smith and R. T. Beyer, J. Acoust. Soc. Am. 40, 257 (L) (1966)]
Authors: McDaniel Oliver H.
Published: September 2005

A proof is given for the derivation of third-harmonic spherical-wave distortion, and several other points raised by Smith and Beyer are corrected and clarified.
Further Results on Binaural Unmasking and the EC Model
Authors: Rabiner Lawrence R. , Laurence C. L. , Durlach N. I.
Published: September 2005

This paper reports the results of further experiments on the binaural unmasking of tones masked by broadband Gaussian noise and further theoretical work on the EC model of binaural unmasking. Data are presented on binaural unmasking for interaural time delays and/or phase shifts in the noise, and for statistically independent noise, at a variety of tone frequencies. Many aspects of these data cannot be interpreted by the preliminary version of the model, and consideration is given to some possible revisions of the model.
Attenuation and Dispersion of Sound by Particulate-Relaxation Processes
Authors: Temkin Samuel , Dobbins Richard A.
Published: September 2005

The temperature and velocity of a particle suspended in an acoustic field are subject to fluctuations that may lag behind those of the surrounding fluid. A theory for acoustic attenuation and dispersion in an aerosol based on these particulate-relaxation processes is given. The close relationship between particulate relaxation and relaxation mechanisms due to lagging molecular or atomic internal degrees of freedom is displayed. The particulate-relaxation theory predicts attenuation and dispersion by small, heavy particles, in close agreement with existing, more-detailed theories, for values of ωτd, (ω is the circular acoustic frequency, τd is the dynamic relaxation time of the particle) smaller than and including order unity. Comparison with existing experimental data of attenuation and dispersion [J. W. Zink and L. P. Delsasso, J. Acoust. Soc. Am. 30, 765–771 (1958)] shows good agreement. However, the existence of a maximum attenuation per wavelength, when ωτd ≈ 1, that is predicted by the theory is not tested by the above experiments, which were conducted with ωτd > 1. Similarly, the maximum dispersion that occurs at the low-frequency limit was not tested in the previous experiments.
Transmission of Sound through a Circular Membrane in a Plane Wall
Authors: Morse Philip M.
Published: September 2005

The acoustic system studied is that of a plane, rigid wall having a circular window in it, across which is stretched a membrane under tension, in contact with an acoustic medium on both sides. A plane wave of frequency ω/2π is directed at one side of the wall plus membrane, at an angle of incidence θ. The integral equations relating the motion of the membrane and the pressure difference across the membrane are obtained. Fairly accurate solutions to these two equations are then obtained by a variational procedure. Values of the functions involved are plotted and tabulated. Formulas are derived for the total power transmitted through the membrane and for the distribution in angle of the transmitted wave; typical plots are given of the results. These are discussed to demonstrate the contribution of the membrane resonances and anti-resonances to the transmitted wave. It is known that an unbounded membrane is transparent to an incident plane wave when the wavenumber of the transverse wave in the membrane is equal to the component of the incident wavenumber parallel to the membrane. The solution for the transmission through a membrane of finite size, obtained in this paper, shows how the resonances and antiresonances, typical of the finite membrane, radically modify the transparency effect.
Torsional-Wave Propagation from a Rigid Sphere Semiembedded in an Elastic Half-Space
Authors: Hill James L.
Published: September 2005

Two problems of torsional-wave propagation from a rigid sphere semiembedded in an elastic half-space are solved in closed form. The first problem treated is the motion of the elastic solid when the angle of twist of the sphere about a vertical line is a given function of time. The second problem is the motion of the sphere and elastic solid when the sphere is subjected to a time-dependent torque about the vertical axis.
Information in Certain Multidimensional Sounds
Authors: Chaney Robert B. , Webster J. C.
Published: September 2005

Twelve sonar-trained and 12 untrained listeners identified 5 physically similar dimensions (quality, inflection, duration, relative frequency, and source) of speech sounds and of sonar signals. Response time, accuracy, and information-rate measures support a hypothesis that perception is more dependent upon prior experience than upon physical properties of signals per se. A second hypothesis was also supported; it suggested that difficulty in identifying each of the five dimensions would be rank ordered differently, both as a function of signal type and listener experience. Auxiliary findings included an apparent superiority of the right ear for listening to speech sounds and of the left ear for other kinds of sounds. Other results suggested that a short-term memory phenomenon was occurring.
Operating Characteristics from Yes-No and Forced-Choice Procedures
Authors: Schulman Arthur J. , Mitchell Rhoda R.
Published: September 2005

Operating characteristics were obtained in yes-no (YN) and two-alternative forced-choice (2AFC) experiments in auditory signal detection. Four listeners used a six-point scale of confidence ratings with each of these psychophysical methods. An extreme rating (1 or 6) indicated high confidence that the signal was or was not presented (in YN) or that the signal occurred in the first or second observation interval (in 2AFC). The two possible events in both YN and 2AFC were equally likely. The signal was a sinusoid of 1000 cps presented for 0.10 sec against a continuous background of noise. Testing was conducted at E/N0's of 7.9 and 15.8. When plotted on double-probability paper, linear operating characteristics provided good fits to the data points obtained from both the YN and 2AFC procedures. The 2AFC operating characteristics, in addition, had slopes near unity. The theory of signal detectability (TSD) correctly predicts a unit slope for the operating characteristics of 2AFC and linear operating characteristics for both YN and 2AFC. New indices of detectability DYN and DFC are proposed to replace the traditional measures to which they are easily related. Each of these new indices is merely the perpendicular distance from a linear operating characteristic to the origin; according to theory, the ratio DFC/DYN should equal √. The eight ratios obtained in these experiments had a mean of 1.46. lending apparent support to TSD.
Effects of One-Dimensional Pressure on the Properties of Several Transducer Ceramics
Authors: Nishi R. Y.
Published: September 2005

The effects of one-dimensional pressure parallel to the polar axis of piezoelectric ceramics have been investigated for a cobalt-modified barium titanate, NRE-4, two strontium-modified lead zirconate titanates, AM-97 and PZT-4, and a niobium-modified lead zirconate titanate, PZT-5. Pressures up to 10 000 psi had little permanent effect on the polarization and coupling factors of AM-97 and PZT-4 but permanently reduced those of NRE-4 and PZT-5. The low-field permittivity decreased initially and then increased with increasing pressure for all materials. At fields up to 3 kV/cm on AM-97 and PZT-4, the permittivity and dielectric loss increased severely with pressures to 10 000 psi; the field dependence decreased to approximately constant values independent of the magnitude of the pressure after several hundred hours. Similar measurements on NRE-4 showed that the changes with pressure and time were not so severe. Changes in the high-field permittivity and loss due to hydrostatic pressure superimposed on a one-dimensional bias pressure were small, provided that the bias pressures were applied to the ceramics at least one week before the hydrostatic pressure. Changes resulting from one-dimensional pressure are explained in relation to domain processes. Implications for underwater-transducer design are discussed.
Energy Spectral Density of the Sonic Boom
Authors: Young J. R.
Published: September 2005

The energy spectral density of ideal sonic-boom pressure signatures has been computed and equations have been developed for the asymptotic behavior of the spectra at high and low frequencies. For systems with essentially high-frequency response characteristics, the system will be basically sensitive to peak overpressure and not to N-wave duration. Low-frequency systems will be sensitive to both duration and peak overpressure. Experimental data are cited to corroborate these conclusions based on the theory.
Even-Order Subharmonics in the Peripheral Auditory System
Authors: Dallos Peter J. , Linnell Craig O.
Published: September 2005

It was observed that the conventional one-half frequency undertones primarily occur above 2500–3000 Hz. In a series of experiments, these subharmonics were monitored in the sound field in front of the tympanic membrane, while first the cochlea and then the stapes were removed. It was found that the presence of the cochlea or the stapes is not necessary for the generation of even subharmonics. These distortion components are radiated by the nonlinearly vibrating eardrum.
Time Separation Pitch Associated with Noise Pulses
Authors: McClellan Max E. , Small Arnold M.
Published: September 2005

Previous research has shown that time separation pitch (TSP) is elicited by the monaural presentation of two ac or dc pulse trains, one train delayed with respect to the other, and is related to the reciprocal of time separation between leading edges of proximal pulses of the two trains. TSP has not been observed previously using uncorrelated noise pulses. On the assumption that TSP is mediated by an autocorrelational process, it was predicted that TSP would obtain using correlated-noise pulses that were produced by an “acoustic delay” system. Uncorrelated-noise pulses served as a control condition. Subjects matched the pitch of a pure tone to the pitches associated with the pulse trains. The results were as predicted. A TSP-like effect arising from continuous-noise samples was discussed and shown to be identical to TSP and, therefore, consonant with an autocorrelational theory. It was concluded that, at least for noise stimuli, temporally discrete waveforms are not necessary to elicit TSP perception; however, a high correlation between temporally adjacent waveforms is necessary to “trigger” TSP perception.
Improving Naturalness and Intelligibility of Helium-Oxygen Speech, Using Vocoder Techniques
Authors: Golden Roger M.
Published: September 2005

Previous analysis of helium speech has shown that the peculiar characteristic of this speech is due primarily to changes in formant frequencies of the speaker. Changes in the fundamental pitch frequency of the speaker are small and usually can be neglected. Computation of the resonant frequencies of the vocal tract, as a function of the gas mixture occupying the tract, gives a reasonable estimate of the changes that can be expected in the formant frequencies. A modified channel vocoder was designed to restore approximately the normal values of the talker's formant frequencies, while preserving his fundamental pitch frequency. This “formant-restoring vocoder” (FRV) separates the spectral energy of the helium speech into a number of narrow bands, which then amplitude-modulate lower-frequency pitch harmonics derived directly from the helium speech. Helium speech from Sealab II was processed by an FRV simulated on a digital computer. Results of several simulations indicated that considerable improvement in naturalness and intelligibility of helium speech can be achieved.
Electrodynamic Vibration Standard with a Ceramic Moving Element
Authors: Dimoff T.
Published: September 2005

This paper describes a new rectilinear vibration exciter specifically developed for accurate calibration of piezoelectric accelerometers. It is an electrodynamic shaker, using a permanet magnet with a ceramic moving element guided by an air-bearing system. The moving element has a simple circular cross section and the driving coil is wound directly onto it. Its first axial resonance is near 25 000 Hz. The working range of the shaker extends from 5000 to less than 5 Hz. The moving element includes a means of mounting an internal accelerometer that can be used as a secondary standard. Alternatively, the moving element/accelerometer assembly can be calibrated by a reciprocity method and used as an absolute standard. The results of measurements of transverse motion and harmonic distortion are presented, as well as an exmple of pickup calibration.
Resonances Excited in an Elastically Connected Double-Beam System by a Cyclic Moving Load
Authors: Kessel P. G.
Published: September 2005

Resonance conditions are derived for an elastically connected double-beam system in which one of the members is subjected to a moving point load that oscillates longitudinally along the beam about a fixed point. The magnitude of the load is also considered to vary sinusoidally. The analysis indicates that, in addition to the usual case of resonance—which occurs when the frequency of load magnitude variation corresponds to a principal frequency of the system for the rth mode of vibration—resonances of the system may occur due to the load-movement frequency. It is found that there are an infinite number of load-movement frequencies that will excite a given principal frequency of the system for the rth mode of vibration.
Measurements of Volume Scattering from a Deep Scattering Layer
Authors: Gold Barry A.
Published: September 2005

Volume-reverberation measurements were made to determine scattering strengths of a deep scattering layer located approximately 250 miles east of Nassau during 18 July 1965. Explosive charges of 2 lb of TNT, used as sound sources, were detonated throughout an 18-h period. Both 13- and 1-oct-band analyses were performed on the data. Scattering strengths, presented in the frequency region from 1.6 to 25.6 kcps, show an increase in amplitude with an increase in frequency. The diurnal change in scattering strengths caused by the deep-scattering-layer migration generally diminishes as frequency is increased. The 13-oct levels range from −82 to −53 dB with the highest levels occurring in the 16.0- and 20.0-kcps bands. The diurnal change in the level of the scattering strength is most pronounced in the 13-oct band centered at 3.2 kcps. Comparisons of scattering-strength characteristics with other published data show agreement in the amount of diurnal variation for a given octave band, diminution of diurnal variation with increased frequency, and an amplitude increase of scattering strengths with increased frequency.
Response of a Flexible Panel to Turbulent Flow: Running-Wave versus Modal-Density Analysis
Authors: Ribner H. S.
Published: September 2005

A feature of the vibration excitation of a plane panel by an idealized model of a turbulent boundary layer has been investigated. In particular, the infinite-panel/running-wave approach has been reexamined for comparison with the finite-panel/modal-density approach. Complete agreement was found on the form of the frequency spectrum of the mean-square panel displacement under conditions where the coincidence effect dominates and reflected waves are negligible. This agreement of the end result provides support for the validity of both methods of analysis since their bases are so different. It furnishes support, in addition, for the notion of a universal smoothed spectrum of the vibration response of panels under the specified range of conditions.
Existence of Longitudinal Waves
Authors: Truesdell C.
Published: September 2005

Hadamard [Leçons sur la propagation des ondes (Hermann Cie., Paris, 1903)] showed that, at a point of a strained elastic body where the elasticity operator is strongly elliptic, the squared wavespeed corresponding to any possible real amplitude is positive. Under the same conditions, we see that at the same point there exists at least one direction in which a longitudinal discontinuity may propagate. Taken together, these two theorems guarantee the compatibility of some real, propagating longitudinal wave.
Vibration of a Thick Cable
Authors: Li Wen-Hsiung , Tang Bor-Ming
Published: September 2005

The undamped free vibration of a thick cable is studied by taking into consideration the effects of its flexural stiffness, shear rigidity, and rotational inertia. These effects can be expressed in terms of a dimensionlesss parameter ε. When the end of a cable of span L is clamped, the influence of flexural stiffness is mainly confined to a distance εL at the end. As a contrast to a beam, a cable is defined as one with ε small as compared with unity, and, therefore, can be analyzed with ε as a perturbation quantity. The cable with clamped ends is analyzed with matched asymptotic expansions, and a simple equation is obtained for the natural frequencies of vibration. Experimental verification has been performed with ε up to 0.1 for the fundamental mode, and with ε up to 0.05 for the second mode.
Axially Symmetric Waves in Hollow, Elastic Rods: Part I
Authors: McNiven H. D. , Shah A. H. , Sackman J. L.
Published: September 2005

A system of approximate, one-dimensional equations is derived for axially symmetric motions of hollow, elastic rods of circular cross section. The theory is valid for a range of wall thicknesses from the very thin to thick walls and, in fact, is valid in the limit for the solid cylinder. The theory takes into account the coupling between the longitudinal, radial, and axial shear modes. The theory is based on expansions of the displacements in a series of orthogonal polynomials in the radial coordinate, retaining only the earliest terms representing the longitudinal, radial, and axial shear deformations. To offset the error introduced by omission of the terms of higher order, four adjustment factors are introduced and chosen in such a way that the behavior of the first three branches of the exact frequency spectrum is reproduced at long wavelengths. Comparison is made between the three spectral lines developed from this theory when the propagation constant is real and the comparable spectral lines from the exact three-dimensional theory.
Objective Audiometry
Authors: Tempest W. , Bryan M. E.
Published: September 2005

It has been suggested [W. D. Keidel and M. Spreng, “Neurophysiological Evidence for the Stevens Power Function in Man,” J. Acoust. Soc. Am. 38, 191–195 (1965)] that human evoked cortical responses to acoustic stimuli have properties that can be related directly to the sensation of loudness. Evidence is quoted to support the argument that, although the evoked responses are certainly related to loudness, the direct equation of sensation magnitude to potential is not entirely justifiable.
Vibration of a Viscoelastic Rod in a Medium Producing Viscoelastic Damping
Authors: Raynor S.
Published: September 2005

A viscoelastic rod coupled to a medium exerting viscoelastic damping shows the property of vibrating in a well-defined frequency band.
Third-Order Elastic Moduli of Polycrystalline Metals from Ultrasonic Velocity Measurements
Authors: Smith R. T. , Stern R. , Stephens R. W. B.
Published: September 2005

The third-order elastic moduli of several isotropic polycrystalline metals have been determined from measurements of the velocities of both longitudinal and shear ultrasonic waves in uniaxially stressed specimens. In each case, the wave-propagation direction was chosen normal to the applied stress, and the shear waves were polarized either normal or parallel to the stress direction. Hence, a unique evaluation of all three third-order moduli was possible using the recent theory of Thurston and Brugger, specialized for isotropic symmetry. The measuring equipment is based on a new variation of the pulse-echo interferometric technique and is capable of resolving velocity changes of a few parts in 106. Results are presented for several steels, aluminum alloys, magnesium, tungsten, and molybdenum, and are shown to be in good agreement with alternative nonlinear elasticity data, including static measurement of the pressure derivatives of the bulk and shear moduli.
Measurements of Attenuation and Dispersion of Sound by an Aerosol
Authors: Temkin Samuel , Dobbins Richard A.
Published: September 2005

Attenuation and dispersion of sound by an aerosol, composed of oleic acid and a nitrogen carrier gas, are measured with an acoustic interferometer. Mean particle size and concentration are measured in situ by spectrophotometric tests. The measurements of attenuation and dispersion show good agreement with the theory in the range of ω(τd)32 covered, where ω is circular frequency and (τd)32, is dynamic relaxation time of the particles. In particular, the maximum attenuation per wavelength and the maximum dispersion, which are predicted by the theory, are confirmed experimentally.
Coupled-Mode Approach to Elastic-Vibration Analysis
Authors: EerNisse Errol P.
Published: September 2005

A variational-approximation technique, which may be interpreted as a coupled-mode theory, is derived for elastic-vibration problems. The theory is valid for the strong coupling that occurs in isotropic and anisotropic elastic material as a result of Poisson's ratio, shear-shear interaction, and/or shear-extensional interaction effects. As an example, the coupled-mode theory is briefly applied to the two-dimensional extensional vibrations of a thin rectangular plate. Calculations for several of the lower branches of the frequency spectrum compare very closely to experimental results obtained with hot-pressed ferroelectric ceramics and to published experimental results. The theory predicts the existence of so-called edge modes, which have been related by past analyses to the complex branches of the dispersion relation. The technique described in this work calculates the resonant frequencies and displacement distributions for these edge modes; real propagation constants and a few zero-order approximations for extensional vibrations are used. The technique produces accurate results, yet physical insight is not obscured by mathematical complexities.
Axially Symmetric Waves in Hollow, Elastic Rods. Part II
Authors: McNiven H. D. , Sackman J. L. , Shah A. H.
Published: September 2005

In Part I of this study [-H.D. McNiven, A. H. Shah, and J. L. Sackman, J. Acoust. Soc. Am. 40, 784–792 (1966)], an approximate theory was developed that governs the relationship between the frequency and the propagation constant for axisymmetric waves in hollow rods, and comparison was made for the lowest three branches contained in the theory with the comparable branches from the exact theory when the propagation constant is real. In this paper, the relationship is explored when the propagation constant is purely imaginary and when it is complex. Frequency spectra are formed from the roots of the frequency equation of the approximate theory, and these roots form a complex branch and a loop on the imaginary plane connecting the second and third spectral lines on the real plane. The imaginary loop and the complex branch are compared to the comparable branches from the exact, three-dimensional theory. Some general properties of all of the complex branches that appear in the exact theory are established.
Signal-Waveform Distortion Caused by Reflection off Lossy-Layered Bottoms
Authors: Nuttall Albert H. , Cron Benjamin F.
Published: September 2005

The acoustic theory for the reflection of a single-frequency plane wave from a fluid layer lying between two semi-infinite fluid media, where the layer and the bottom medium are subject to attenuation, is reviewed. Applying the experimental fact that the attenuation is proportional to the first power of frequency to this theoretical model of the ocean bottom, we show that the effect on impingent plane waves may be treated as a parallel linear-filtering operation with a component transfer function of the basic form H (f) = exp[−2πb|f|+iε sgn (f)]. The parameters b and ε depend on the media physical constants, the angle of incidence, and the particular reflected component under consideration. Here, f is frequency in cycles per second, 2πb is attenuation in nepers per cycles per second, ε is phase shift in radians, and sgn (f) = 1 for f>0, −1 for f <0. For this basic type of transfer function, the component reflected pulse is first derived generally in terms of the incident pulse, the attenuation, and the phase shift. Component reflected-pulse shapes for some specific incident pulses, including a carrier, amplitude-modulated by a rectangular pulse, a sinc pulse, an exponential pulse, and a Gaussian pulse with linear frequency modulation (FM), are then derived in terms of tabulated functions and are numerically evaluated. A method is presented which can treat the total reflected signal in complete generality for arbitrary amounts of loss and angle of incidence, and a variety of waveshapes with arbitrary Q, phase, and bandwidth. The answer is given by amplitude scaling, delay, and summation of component pulses, several of which are presented. Furthermore, the method is applicable to media with several lossy layers, once the components are individually identified and their coefficients, delays, and attenuations are computed.
Vocal Response of the Bullfrog to Natural and Synthetic Mating Calls
Authors: Capranica Robert R.
Published: September 2005

Vocalizations have been evoked from the males of laboratory colonies of bullfrogs in response to natural and synthetic bullfrog mating calls. The vocal responses, having the signal characteristics of the bullfrog's mating call, are species-specific and highly selective: to playbacks of the recorded mating calls of 34 representative species of frogs and toads, only the calls of certain male bullfrogs would evoke calling from the laboratory animals. Studies of evoked calling to a variety of synthetic mating calls have led to a model whereby the degree of calling evoked by a given stimulus can be qualitatively predicted on the basis of its spectral structure and temporal periodicity. The model has satisfactorily accounted for the selective responses to some natural bullfrog mating calls and the absence of responses to others. The close relationship of the model to recent electrophysiological findings in the peripheral auditory system of the bullfrog is discussed.
Effect of Signal Duration on the Auditory Sensitivity of Humans and Monkeys (Macaca mulatta)
Authors: Clack T. Dean
Published: September 2005

The changes in absolute sensitivity of monkeys and humans are compared as a function of signal duration. Pure tone thresholds, both monaural and binaural, were obtained from the two monkeys (Macaca mulatta) using a single-lever, go no go, shock-avoidance conditioning procedure. The monaural thresholds for the seven women were determined under similar acoustic and behavioral conditions. The signal durations sampled were from 10 to 1500 msec at frequencies between 250 and 8000 cps. The results show that (1) the rate of change in threshold as a function of signal duration is linear with a slope dependent upon frequency—slope is highest below 1000 cps for both humans and monkeys; (2) although the integration rates for humans and monkeys are nearly identical at 2000 and 4000 cps, they differ at the frequency extremes. An attempt is made to show that these results do not depend upon the critical-ratio differences of the ears but are related to long-term sensitivity.
Decision Rules in Threshold Determination
Authors: Stuckey C. W. , Hutton C. L. , Campbell R. A.
Published: September 2005

Threshold determination within the framework of the Block Up-and-Down, Two-Interval, Forced-choice (BUDTIF) method has been investigated. A computerized Monte Carlo technique was used to permit varying certain procedural parameters while maintaining an invariant “listener.” The basic approach involved a comparison of the threshold means and variances obtained for a representative set of parameter values. That set of parameters yielding minimum between-mean threshold variance and minimal bias was sought. Parameters considered and general results included (1) number of trials per run—inversely related to between-mean threshold variance, (2) number of trials per block—directly related, with a critical minimum size depending on target performance level, (3) number of blocks used in each level-change decision—directly related, (4) initial stimulus level—no effect, if reasonably close to true threshold, and (5) method of calculating thresholds—no clear effect. Parameters that yielded minimum variance within individual runs tended to yield maximum variance between successive threshold estimates.
Behavioral and Pinna-Reflex Thresholds in the Rat: Audiometric and TTS Covariations
Authors: Clack T. Dean
Published: September 2005

The hypothesis that the Preyer-reflex threshold is related to the absolute intensive threshold is supported by data on the two kinds of thresholds from five white rats. The threshold audiograms are similar (the Preyer about 60 dB less sensitive) and they exhibit roughly the same amount of temporary, threshold shift to acoustic stimulation and the same recovery slope. One animal showed a “bounce” in recovery for both thresholds, and one showed hypersensitivity of the reflex after stimulation.
Ultrasonic Irradiation of Enzyme Solutions
Authors: Macleod R. M. , Dunn Floyd
Published: September 2005

It is shown that inactivation of enzymes in solution by 3-MHz ultrasound in the intensity range 1–3 W, cm2, which has been reported by other investigators, is, in fact, due to the presence of rubber materials used as part of the containing vessel during the experiments.
Effect of Noise, System Gain, and Assigned Task on Talking Levels in Loudspeaker Communication
Authors: Gardner Mark B.
Published: September 2005

Results of the present study show that the specification of talking levels in vocal communication is meaningful only to the extent that the conditions involved are also specified. This is true for both face-to-face communication and for communication over a two-way loudspeaker system—the latter forming the principal basis of the experimental results to be presented. For this type of communication, the test participants made a relatively small, reversible adjustment of their vocal outputs over a range of system gain from +10 to −40 dB re unity. On the other hand, there was always a unidirectional change (increase) in talking level with increasing noise to effect a compensation within 3 dB of optimum listening level over a noise-level range of 37 dB. The above results were supplemented by repetition-rate data and by appraisals of the degree of acceptability of the communication achieved under various test conditions for participants communicating in pairs over the system (one individual at each terminal). Over all, the data indicate the importance of operating under as favorable a noise condition as possible and the maintenance of system gain (as defined) at, or slightly below, unity for such use of this type of communication facility.
Experimental Studies in Speaker Verification, Using an Adaptive System
Authors: Li K. P. , Dammann J. E. , Chapman W. D.
Published: September 2005

This paper describes an investigation of the capability of a two-level adaptive linear threshold element (LTE) system to perform speaker discriminations. The study also includes an investigation of discriminating a speaker from an unknown population. The problem has been confined to the verification of an utterance as that of an expected informant. The environment of the experiments is discussed, and the experimental system is described. At the first level LTE, four different kinds of training have been developed for effective transformation and data reduction. At the second-level LTE, different training conditions and different decision processes are investigated and evaluated. Over 90% accuracy is obtained in separating a known speaker from impostors.
Perception of Segments of VCCV Utterances
Authors: Öhman S. E. G.
Published: September 2005

Perceptual confusions among Swedish consonants in VC and CV syllables are investigated. The stimuli were produced by splitting natural VCCV utterances in two halves at various points in time. The initial and final stimuli so obtained were used for two separate listening tests. The perceptual errors associated with the various VC and CV stimuli of any given VCCV utterance are analyzed with respect to the manner, place, and voicing features of the intervocalic consonant. Explanations of these errors in terms of acoustic and linguistic properties of the stimuli are attempted.
Radiation Resistance, Cavitation Factor, and Beam Patterns for Steered, Closely Packed, Rectangular Arrays in a Rigid Plane
Authors: Chin Norman T.
Published: September 2005

A large, closely packed, steered array is modeled by imposing a traveling wave along the surface of a rectangular radiator. The results in this paper are most pertinent to closely packed arrays made up of elements that are small as compared with a wavelength. For this type of array, it is shown that at large steering angles the cavitation-limited power is greatly reduced below that achievable at broadside. The cavitation factor is generally less when the beam is steered along the longer side of an array than when the beam is steered across its shorter side. Integral solutions for the nearfield pressure and radiation resistance of a general steered array are presented. Numerical results show that the radiation resistance has a maximum value at a particular steering angle for a specific array, and the nearfield pressures pile up near the leading edge of the array as the beam is steered to a large angle. In the end-fire case, approximate expressions for the radiation resistance and the nearfield pressure are derived for an infinitely long rectangular strip with beam steering across the width, and for a finite, slender, rectangular array with beam steering along the longer side.