The speed of sound in a medium is determined by its density and elasticity. When density increases, the speed of sound tends to decrease. This relationship can be explained by the way sound waves propagate through a medium.
Sound waves are longitudinal waves, meaning that the particles in the medium vibrate parallel to the direction of wave propagation. As a sound wave travels through a medium, it causes compressions and rarefactions of the particles in that medium. In a denser medium, the particles are closer together, which means that they can interact more frequently with neighboring particles.
When a sound wave passes through a denser medium, the increased particle interactions lead to a higher frequency of collisions and interactions. As a result, the particles are slowed down more, and the overall speed of sound decreases.
Additionally, the elasticity or stiffness of the medium also plays a role. A denser medium typically has higher elasticity, which means that the particles in the medium are more tightly bound and resist being displaced. This increased stiffness further contributes to the decrease in the speed of sound.
In summary, the speed of sound decreases with an increase in density because denser mediums have more frequent particle interactions and higher stiffness, causing a slower propagation of the sound wave.