|MadSci Network: Physics|
Hi, This phenomenon is quite simply due to the fact that air absorbs high frequencies more heavily than low frequencies. Since the viscosity of air is finite, a rapid pressure change will cause more friction loss in air than a slow pressure change. As you move further away from the sound source, more and more high frequencies get absorbed compared to the low frequencies. This property is strongly temperature and humidity dependent. Some figures are given here: http://www.sfu.ca/sonic-studio/Sound_Propagation.html Regards, Bruno
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