If you want to listen to faint sounds far away, you’re going to need a bigger ear. Parabolic microphones gather and focus sound waves the way a satellite dish focuses radio waves, making it possible to listen to the quietest of sounds hundreds of feet away.
Now while this is an interesting build it won’t replace having a good microphone within close proximity to your subject. As always – we must turn to science. (Wikipedia)
Parabolic microphones are generally not used for high fidelity recording applications because dishes small enough to be portable have poor low frequency (bass) response. This is because, from the Rayleigh criterion, parabolic dishes can only focus waves with a wavelength much smaller than the diameter of their aperture. The wavelength of sound waves at the low end of human hearing (20 Hz) is about 17 metres (56 feet); focusing them would require a dish much larger than this. A typical parabolic microphone dish with a diameter of one metre would have little directivity for sound waves longer than 30 cm, corresponding to frequencies below 1 kHz.
Still if you just want to hear something far away, this might be a fun build.