From Wikipedia, the free encyclopedia
A parabolic microphone is a
microphone that uses a
parabolic reflector to collect and focus
sound
waves onto a receiver, in much the same way that a
parabolic antenna (e.g.,
satellite dish) does with
radio waves. Typical uses of this microphone, which has
unusually focused front sensitivity and can pick up sounds from
many meters away, include nature
recording, field audio for sports broadcasting,
eavesdropping,
law enforcement, and even
espionage.
Parabolic microphones are generally not used for standard
recording applications because they tend to have poor
low-frequency response as a side effect of their design. This is
a direct result of the physical laws that govern sound waves.
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 342 m/s / 20 Hz = 17 meters in diameter.
Most parabolic microphones sacrifice low-end fidelity to get a
more manageable size.
External links
-
Do-it-yourself parabolic microphone site 1
-
Do it-yourself parabolic microphone site 2
Categories:
Microphones |
Surveillance
