Answer:
Speed of sound wave increase.
Step-by-step explanation:
There are many factors on which the speed of the sound wave depend i.e. temperature, density etc.
It also depends on the type of medium i.e. either solid, liquid or gas. It is maximum in solid than liquid and gases. It is about 6420 m/s in aluminium, 6040 m/s in nickel. In air the speed of the sound is least.
Hence, as we move from the air through a soil, the speed of the sound increase.