Question

why does sound become faint with distance?

Answer 1

As distance from the sound source increases, the area covered by the sound waves increases. The same amount of energy is spread over a greater area, so the intensity and loudness of the sound is less. This explains why even loud sounds fade away as you move farther from the source.

Answer 2

Two things are happening:

1. Sound spreads in a sphere, like a balloon that gets inflated. As the sound spreads over a larger area the sound gets fainter.
2. As you are moving away from the source of the sound it takes more and more time between the arrival of the start of a soundwave and the end of a soundwave. This will cause the sound to go lower and lower but also to sound fainter.