What occurs when sound waves enter a medium of lower density?

When sound waves enter a medium of lower density, the correct response reflects that the speed of sound decreases. This phenomenon can be understood through the relationship between the density of a medium and the speed of sound traveling through it. Sound waves propagate through the compression and rarefaction of particles in a medium. In denser materials, particles are closer together, allowing sound waves to transfer energy more efficiently, resulting in a higher speed of sound.

Conversely, when sound waves encounter a medium with lower density, the particle spacing increases. This increase in distance between particles means that the transfer of energy becomes less efficient, leading to a decrease in the speed of sound. This is well-documented in acoustics and is further illustrated by the fact that sound travels faster in solids than in liquids, and faster in liquids than in gases. Thus, the interaction of sound waves with a medium of lower density clearly causes a reduction in their speed.