Volume 16, Issue 2, October 1944
Index of content:
A Clinical Comparison of Air and Bone Conduction Hearing Aids in Cases of Conductive Impairment of Hearing16(1944); http://dx.doi.org/10.1121/1.1916269View Description Hide Description
16(1944); http://dx.doi.org/10.1121/1.1916270View Description Hide Description
A method for measuring the modulus of elasticity of fibers and films by sonic means is described and the results of an exploratory study of the modulus in various natural and synthetic fibers and films are given. The method is based on the equation for the propagation of longitudinal waves in elastic materials, which expresses the velocity of propagation in terms of the elastic modulus and density of the medium. The procedure involves measuring the sound velocity and calculating the modulus, using the proper density value. The modulus so calculated is characteristic of a dynamic, short period measurement, since a sound frequency of approximately 10 kilocycles per second was used. The range of moduli found was from 1×1010 to 50×1010 dynes per square centimeter. Correlations of moduli with other physical properties are given.
16(1944); http://dx.doi.org/10.1121/1.1916271View Description Hide Description
The study of sound propagation in gases has revealed useful data concerning molecular behavior. Vapors, with little known about their absorption and dispersion to sound at audible frequencies, provide a natural field for extending such studies. In the present investigation, a form of Kundt's tube is employed in which a hot wire records the amplitude in the stationary wave system. It is calibrated by the use of dry air and of oxygen. The results obtained for the velocity of sound are in good agreement with those determined by other methods.