Answer the following question given this paragraph: 

The energy of sound waves spreads out over a greater area as the waves travel farther from the sound source. This diagram represents just a small section of the total area of sound waves spreading out from the source. Sound waves actually travel away from the source in all directions. As distance from the source increases, the area covered by the sound waves increases, lessening their intensity.


Q: As distance from the source increases, the area covered by the sound waves increases, lessening what?


A:
intensity