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The physics of parabolic microphones: Frequency dependence of gain (2023)

Introduction [latexpage] Parabolic microphones are known for their extreme sensitivity, and the origin of their acuity isn't difficult to guess. It is the most obvious thing about them, which can also make them a liability for field use, namely, their considerable size. Just as a large amount of weak light is captured by a telescope's

Just as a large amount of weak light is captured by a telescope’s parabolic mirror and made amenable to viewing with the much smaller human eye, so too are faint sounds harvested with a reflecting dish that far exceeds the dimensions of our native auditory tools. We will simplify this by representing the train of waves as a single “pulse” expanding outwards, and we’ll also imagine the water is in a perfectly circular pool with the pebble striking in the exact center. In this case, the same receiver will intercept a much larger fraction of the total power.Now consider the other extreme, in which an aperture emits waves with a wavelength that is much smaller than it is, as animated in the center frame of figure 9 and shown here in diagram (b).

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