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. Sound entering the parabolic dish from the front axis is reflected into a sphere around the "focus" of the dish, where the microphone element is located. The higher the frequency of the sound, the smaller the size of this sphere. Thus, high frequency sounds tend to be more concentrated onto the pickup element, while low-frequency sounds are "diluted" across a larger volume of space.
See also: Microphone