Brownout look here;Parabolic microphone - Wikipedia, the free encyclopedia
and I quote
I saw the same thing mentioned many times the other night when I was looking for evidence that a 1/2 round would be better than a dish.
Andy
and I quote
Parabolas only focus waves with a wavelength much smaller than the diameter of the parabola. Since sound waves travel at 342 m/s through the air (speed of sound), obtaining hi-fidelity sound (down to 20 Hz, the lower limit of human hearing) would require a parabola with a diameter greater than 17 meters (= 342 m/s / 20 Hz). Most parabolic microphones sacrifice low-end fidelity to get a more manageable size.
I saw the same thing mentioned many times the other night when I was looking for evidence that a 1/2 round would be better than a dish.
Andy