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THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

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290 12. Walls, Enclosures, and BarriersFigure 12.6. A double-panel partition.The individual spring constants are related to the spring constant of the compositespring by1k = 1 + 1 . (12.17)k 1 k 2Eliminating k 2 between Equations (12.16) and (12.17) results ink 1 = k m 1 + m 2.m 2Inserting the last expression into the first portion of Equation (12.16) yields thenatural frequency f n of the system:√k m 1 + m 2mf n = 1 m 2. (12.18)2πIn order to establish the effective spring constant of the air between the panels,it will be assumed that an isentropic process constitutes the action of sound waves,since the pressure changes occur too rapidly for an isothermal process to take place.From thermodynamics, for an isentropic process the pressure p of air (consideredFigure 12.7. Spring-mass analogy of the double-panel partition of Figure 12.6.

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