Why does the energy of a sound wave decrease over time

It is transferring from particle to particle and travels that way. But each transfer is not 100% and it gradually dies out. So, in other words, as the distance increases the intensity of the sound wave decreases.

Black round and partialy brown with little hairs that stick out, or a little creature that digs in the dirt that has wird pink whiskers in the front of its nose thats partily blind