Sound is a form of energy. It travels from one place to another through a medium like air. It can also travel through other gases such as helium, and can even travel through liquids and solids. The only thing sound cannot travel through is a vacuum like space.
When an object moves back and forth, or vibrates, it pushes the air molecules next to it. As air molecules get compressed into waves, the energy is transferred from molecule to molecule until it is exhausted. That is why sounds that are farther away sound softer — their energy fades as they travel.
Sound waves travel at different speeds depending on the temperature of the air. At 44 degrees Fahrenheit, sound travels approximately 1,100 feet per second, or 750 miles per hour. To put this into perspective, sound waves travel the distance of 1 mile every 5 seconds.
What if it becomes harder to hear God because we have moved further from him? All communication from God would become a whisper. Then it would become fainter an fainter!