The speed of sound waves depends on the properties of the medium through which they travel. In general, denser substances are more elastic and have a higher bulk modulus, which means that they resist compression more strongly. This leads to a faster propagation of sound waves.

Mathematically, the speed of sound in a medium is given by the equation:

$$v = \sqrt{\frac{B}{\rho}}$$

where:

- \(v\) is the speed of sound in meters per second (m/s)

- \(B\) is the bulk modulus of the medium in pascals (Pa)

- \(\rho\) is the density of the medium in kilograms per cubic meter (kg/m³)

From this equation, it can be seen that the speed of sound is directly proportional to the square root of the bulk modulus and inversely proportional to the square root of the density. Therefore, as the bulk modulus increases and the density decreases, the speed of sound increases.

It's important to note that other factors, such as temperature and composition, can also influence the speed of sound in a medium. For instance, increasing the temperature of a substance generally decreases its density, which can lead to an increase in the speed of sound.