Sunday, April 14, 2019

acoustics - How to calculate effective sound impedance


Sound reflection/transmission at boundary depends on impedance.While electrical impedance depends on frequency,resistance,capacitance and inductance,sound impedance depends too on frequency but instead of reactive factors we have mass and stiffness.



I would like to know how does effective impedance of wall of certain stiffness and mass change when we double either mass,stiffness or frequency.Does doubling of either of these double impedance?


I saw this equation that calculates the impedance of wall,could you please help me understand it? I have good understanding of the physics of sound but I have almost no skill with equations.


What I need is someone to explain in detail step by step every aspect of equation,show me what every symbol represents in real world,in what units,make a guide to show how to tackle each step in solving the equation,be very verbose.


$$Z_{total}(f) = \ i \ 2 \pi f m \ \ + \ -i \ \frac{\kappa}{2 \pi f}$$


Its equation by D.Betchkal from this question Physically, why are high sound frequencies more easily absorbed than low sound frequencies?


I understand "(f)" is sound frequency in Hertz,I understand Z is acoustic impedance,in what units I dont know ( there are two types of Rayls ),the rest I dont understand.




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