摘要:

Determination of the elastic and piezoelectric constants for crystals in class (3m) is complicated by the large number of independent constants and the many possible ways in which they may be combined. An experimental and analytical procedure has been developed to determine all the constants using primarily thickness‐mode measurements made on small, plate‐shaped samples of various crystallographic orientations, and results using this procedure have been obtained for lithium tantalate and lithium niobate, two recently developed synthetic crystals. The resonant and antiresonant frequency constants for thickness modes have been calculated as functions of a plate's rotation angle. Information in this form makes possible the selection of plate orientations that might be useful as resonators and transducers.

ISSN:0001-4966    

DOI:10.1121/1.1910709

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

Time‐dependent Fourier analyses of the attack transients and steady states of about 900 trumpet, trombone, tuba, and French‐horn tones yielded the amplitudes and relative phases of the first 11 partials. Relative component amplitudes for all tones of an instrument played at a given dynamic marking are approximately described by a spectral envelope. The partials are conveniently divided into those below a cutoff frequency (Class 1 components) common to all notes of the instrument and those above it (Class 2). Class 1 components have similar attack envelopes and reach approximately equal steady‐state values before those in Class 2. The transient periods for Class 2 components increase with frequency of the components, and their steady‐state values decrease rapidly with increasing frequency of the components. Amplitude modulations (blips) that last for one or only a few cycles of the modulation occur for all components during the end of the transient, but are larger for Class 2 components. For brasses other than the French horn, spectral envelopes are approximately frequency‐scaled versions of each other. Rolloff rates above the cutoff frequency decrease as the average amplitude of a scale of notes increases, and it appears that an increase in radiated power is achieved primarily by an increase in the amplitudes of high‐frequency partials. Average rolloff rates in decibels per octave for scales played at an average sound pressure level of 68 dB were: trumpet, 15; trombone, 20; tuba, 17; unstopped horn, 16; stopped horn, 30.

ISSN:0001-4966    

DOI:10.1121/1.1910710

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

By use of a time‐varying volume representation for the cylinders, an acoustical equivalent circuit for a multicylinder engine air‐induction system is developed, and a general solution for the acoustic pressure is derived. A commercial four‐cylinder engine is used for a comparison between the analytical and experimental results. It is shown that the agreement is closer than when a conventional time‐invariant equivalent circuit is used for the engine cylinders.

ISSN:0001-4966    

DOI:10.1121/1.1910711

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

The ability to identify talkers from monosyllables spoken in context was examined: Kersta's method of visually comparing spectrograms was employed. Ten observers were trained to identify five talkers from spectrograms of two words spoken in isolation. The experimental task then required the observers to identify the same talkers from the same words spoken in different contexts. The correct rates for the training task (78.4%) could not be reproduced in the experimental task (37.3%). The results were interpreted to indicate that different contexts decrease the identification ability of observers because: (a) the shorter stimulus durations of words in context decreases the amount of acoustic information available for matching, and (b) the different spectrographic portrayals introduced by different phonetic contexts outweighs any intratalker consistency.

ISSN:0001-4966    

DOI:10.1121/1.1910712

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

The intensity distribution in the orders of a light‐diffraction pattern produced by the interaction of a progressive ultrasonic surface wave and a monochromatic light beam is calculated. The amplitude of the surface wave is determined from the light‐intensity distribution in the diffraction pattern. The spacing of the diffraction orders is related to the surface wave velocity and the angle of light incidence.

ISSN:0001-4966    

DOI:10.1121/1.1910713

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

A pulsed ultrasonic light diffraction technique was used to obtain values of the piezo‐optic coefficient for 24 liquids. From these results, several empirical expressions were obtained that facilitate calculation of this parameter.

ISSN:0001-4966    

DOI:10.1121/1.1910714

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

The frequency spreading of a monochromatic acoustic plane wave reradiated by the moving, rough surface of the ocean is described using the spectral density of the far‐zone reradiated pressure. This pressure is calculated using the method of physical optics for a surface assumed to be described by the Neumann‐Pierson directional wave spectrum. The results are specialized for the cases of slightly rough and very rough wind‐generated seas. For the slightly rough case, the spectral density contains a specularly reflected component at the frequency of the incident radiation and two monochromatic scattered components that are Doppler‐shifted by equal amounts from the frequency of the incident radiation. The magnitude of the deviation of each of the Doppler‐shifted frequencies is the same and depends on the angles of incidence and observation relative to the wind direction and also on the incident frequency. For the very rough surface case, the spectral density of the far‐zone reradiated pressure is of Gaussian form. In the specular direction, the center of the spectrum is at the frequency of incident radiation but is shifted away from that frequency for other angles of observation with a shift proportional to wind speed. The width of the spectrum increases as the three‐halves power of the wind speed and also depends upon the geometry.

ISSN:0001-4966    

DOI:10.1121/1.1910715

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

Equations of motion accommodating thickness‐twist overtones of thickness‐shear and flexural vibrations of rectangular,AT‐cut, quartz plates are obtained. The equations are solved in closed form for plates with all four edges free. The predicted frequencies are compared with measured resonances. X‐ray topographs of typical thickness‐twist overtone modes are exhibited which verify that the mode shapes correspond to those predicted.

ISSN:0001-4966    

DOI:10.1121/1.1910716

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

Frequency equations and mode shapes are obtained in analytic form for the axisymmetric, extensional, nontorsional vibrations of fluid‐filled elastic spherical shells and rigid prolate spheroidal shells, while a numerical scheme is developed for the fluid‐filled elastic prolate spheroidal shell. Extensive numerical results in the form of frequency spectra and mode shapes for these problems are displayed.

ISSN:0001-4966    

DOI:10.1121/1.1910717

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

An approach to three‐dimensional ray tracing, based on the ray equations and Frenet formulas, is developed. It is applied to two families of constant sound‐speed surfaces for which Snell's laws are not known: coaxial circular cylinders and concentric ellipsoids. The classically known results for the cases of parallel planes and concentric spheres are rederived in terms of the present formulation. It is shown that the ray‐tracing equations for concentric spheres can be transformed exactly into those for parallel planes. For the coaxial cylinder case, pseudo‐Snell's laws can be derived even though the ray paths are not plane curves. For the family of ellipsoids, no Snell's law was found, but ray paths are plane curves. The examples considered do not exhaust the applicability of this ray‐tracing approach, but are meant only to illustrate the technique.

ISSN:0001-4966    

DOI:10.1121/1.1910718

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP