The propagation of high frequencies sound waves is more directional (specular),
ID: 1391724 • Letter: T
Question
The propagation of high frequencies sound waves is more directional (specular), and they don't diffract as much as low frequencies. Low-frequencies diffract and thus propagate in a more omni-spherical fashion. This, to my knowledge, applies to all waves, not only sound ones.
Now trying to imagine the air particles hitting one another at low/high frequencies doesn't really unlock why this happens. I am aware that deep understanding of wave theory will provide the answer.
But is there a simple, visual explanation to why this happens? And if not, is there at least some simple mathematical equation that can provide the answer?
Explanation / Answer
Diffraction angle on the body of size L is about ?/L thus it is bigger for LF waves.
Another way to think about it is to remember that ??0 case is a geometric optic with no diffraction at all, and the bigger the wavelength is, the further we away from the geometric optic to meet diffraction, etc.
PS. I am not sure the picture of particles hitting each other plays well here because of the ideal acoustic targets cases with wavelength much bigger than mean free path in order to arrive to the dissipation-free wave equation we use to describe the diffraction.
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