greentea Posted June 19, 2005 Share Posted June 19, 2005 A friend just asked me how does wind affect the propagation of sound and I am ashamed to say I do not exactly know. It is experienced that when the wind blows from different directions, you would hear a distant sound differently. Obviously changes in pressure will affect some characteristics of the sound wave, but I cannot think of a model. Any ideas? Link to comment Share on other sites More sharing options...
DQW Posted June 19, 2005 Share Posted June 19, 2005 This is pretty well established. The speed of sound in a wind is greater than the speed of sound in still air by the component of the wind velocity along the direction of propagation. This effect will Doppler Shift the frequency of the sound, just as a moving observer would. [math]f(wind~blowing~toward~you)=f(no~wind) \frac {c+c_w} {c} [/math] [math]f(wind~blowing~away~from~you)=f(no~wind) \frac {c-c_w} {c} [/math] Link to comment Share on other sites More sharing options...
greentea Posted June 19, 2005 Author Share Posted June 19, 2005 so, it's just doppler shift. I thought of that, but seemed too simple to be true. how about wind blowing perpendicular? Link to comment Share on other sites More sharing options...
DQW Posted June 19, 2005 Share Posted June 19, 2005 how about wind blowing perpendicular?It's the component of the wind velocity along the direction of interest that you want [imath]c_w cos \theta [/imath]. For a perpendicular wind, there should be no effect, according to this simplistic theory. There may be lower order effects, and also, winds are never in laminar flow, so the provided expression is only an approximation. Link to comment Share on other sites More sharing options...
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