摘要:

Data on confusions in short‐term memory between English consonants [W. A. Wickelgren, J. Acoust. Soc. Am.39, 388–398 (1966)] have been reanalyzed within the framework of binary features. A new method of analysis is described that involves a similarity metric. The method produces an evaluation of individual features and associates a confidence level with each statement made about the data. With a confidence level greater than 0.99, it is shown that long frication, continuant, sonorant, sibilant, and voiced are features present in the data of Wickelgren. The issues of feature independence, completeness of a feature system, and the derivation of optimal features are treated. The advantages of the similarity metric over rank‐order statistics, multidimensional scaling, and information transfer are discussed.

ISSN:0001-4966    

DOI:10.1121/1.1911094

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

A study of speech‐quality measurement procedures requires a working definition of the over‐all concept of speech quality. It is assumed that speech quality can be described in terms of intelligibility, preference, loudness, and speaker recognizability. A utilitarian approach to the measurement of preference, the isopreference method, is presented and discussed. In this method, preference is evaluated in a forced pair‐comparison test and is described in terms of a continuously variable reference signal. The results of extensive testing and test repetitions indicate that the accuracy of preference evaluations is not limited by the proposed method, but by variety and variability of listeners and by training and accommodation effects for given sets of test signals.

ISSN:0001-4966    

DOI:10.1121/1.1911095

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

A crystal ultrasonic interferometer has been utilized to measure velocity dispersion in ethane‐argon mixtures at 304.1°K and up tof/Pvalues of about 108cps/atm. The double‐relaxation characteristic of ethane persists, and relaxation times are only slightly affected by the addition of argon. Treatment of the relaxations as parallel processes gives relaxation times for ethane argon collisions. Considering the argon atoms as a Lennard‐Jones 6:12 “probe” yields a value for the ethane repulsive range that is in excellent agreement with the Schwartz Slawsky Herzfeld theory for a 6:12 relaxing gas.

ISSN:0001-4966    

DOI:10.1121/1.1911096

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

The exact solution to the problem of an axially‐invariant elastic wave propagating in an infinitely long cylinder of isotropic material having a traction‐free curved surface was first given by Pochhammer in 1876. The solution has been extended by Redwood and others to include axially variant waves. In the present work, we have derived expressions for the propagation of waves in an infinite circular cylinder of material having hexagonal crystal symmetry, where the axis of the cylinder coincides with the crystallographiccaxis. Normalized plots of phase velocity vs frequency are shown for representative isotropic and hexagonal materials. The plots have been extended to sufficiently high order that the form of all higher modes can be extrapolated. For materials of hexagonal crystal symmetry, we have found that the phase velocity plots do not change in form from those of isotropic materials, but are displaced by small amounts dependent upon the particular elastic constants chosen.

ISSN:0001-4966    

DOI:10.1121/1.1911097

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

A motor‐driven ultrasonic goniometer is described consisting of a single transducer and a 90° reflector. This relatively simple device facilitates rapid investigation and automatic recording of reflection data. The reflectivity curves are interpreted in terms of reflector geometry and the physical properties of the specimen. Among other things, the technique has been used to determine surface‐wave velocities in theY‐Zplane of quartz, and the results are shown to be in reasonable agreement with both theoretical and other experimental data.

ISSN:0001-4966    

DOI:10.1121/1.1911098

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

Ultrasonic measurements which were designed to test the theory of reflections of harmonics generated by finite amplitude waves at stress free boundaries in solids have been made. The results are found to be in agreement with theoretical expectations.

ISSN:0001-4966    

DOI:10.1121/1.1911099

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

The dispersion attenuation of waves in viscoelastic tubes filled with a viscous incompressible fluid are analyzed, with special attention to two cases: where the constitutive relation of the wall is that (1) of a Voigt material, and (2) of a standard linear solid. Explicit expressions show the dependence of the phase‐velocity and damping factor on the various parameters characterizing the fluid and the viscoelastic tube. In comparison with elastic tubes, viscoelastic tubes have a higher phase velocity and attenuation coefficient. Also, as the ratio of the relaxation time of the viscoelastic material to the period of the oscillation increases, there is a marked difference between the behavior of the waves for the two types of materials considered. The frequency equation for a stretched elastic tube is also derived. The analysis is restricted to waves whose amplitude is infinitesimal with the wavelength large and the wall thickness small as compared with the radius of the tube.

ISSN:0001-4966    

DOI:10.1121/1.1911100

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

We discuss conditions under which relatively weak discontinuities can propagate in liquid crystals, assuming these are incompressible and neglecting temperature variations. Loosely speaking, these assumptions tend to suppress waves that would occur in simpler liquids, thus they emphasize the waves that are peculair to liquid crystals. A primary feature is that they involve disturbances in orientation. As a general rule, there are accompanying perturbations of the motion.

ISSN:0001-4966    

DOI:10.1121/1.1911101

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

The transimssion of plane harmonic waves normally incident on a transition zone with arbitrary velocity and density variations in a fluid or an elastic medium is studied theoretically. The general solution for a one‐dimensionally heterogeneous, isotropic medium is obtained in a series form by integrating the Volterra integral equation for the particle displacement. The reflection and transmission coefficients are derived from this solution.

ISSN:0001-4966    

DOI:10.1121/1.1911102

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP

摘要:

An arbitrary excitation of the planex= 0 sends sound signals into the half‐spacex⩾ 0 occupied by the viscous fluid. The governing third‐order partial differential equation is solved exactly using the Laplace transform on time and the sine transform on space. New expressions for the most general solution are derived. The specific inputs considered in detail are the Dirac delta function, the Heaviside unit function, a decaying exponential, and a sinusoidal excitation. The final expressions are given in the form of real integrals and of exact power series. Short‐time approximations are also given for a general input and for the four aforementioned specific inputs. Previously obtained approximations for the case of small attenuation coefficients are corrected and extended for the decaying exponential and the sinusoidal input. The results found indicate that viscosity tends to reduce the sharpness of the propagating disturbance and thus to smooth out any initially imposed discontinuity. The presence of the disturbance is felt immediately everywhere in the medium, and, in fact, the short‐time approximations satisfy the parabolic heat equation.

ISSN:0001-4966    

DOI:10.1121/1.1911103

出版商:Acoustical Society of America    

年代:1968

数据来源: AIP