Answer:
The sound travels faster through the stiffer material of the ground than is does through the air.
Step-by-step explanation:
Sound is a mechanical, longitudinal wave that is caused by the vibration of molecules.
A mechanical wave is a wave that requires a medium through which to travel, as opposed to electromagnetic waves which do not require mediums.
Ground being solid has a very tight arrangement of particles. Due to less spacing sound or vibrations can easily be passed on to the next particle where as in gases due to lower density and larger distance of particles with the gas , the vibrations are not passed on easily to the next particle as in solids.
Hence sound actually travels around four times faster in solid such as ground than in gases such as air. Speed of sound in air is 343 meters per second. Speed of sound in solids has a wide range depending on the density of the solid.