### Theory:

Factors affecting the velocity of sound:

The velocity of sound waves in gases is affected by the following factors.

- Effect of Density
- Effect of temperature
- Effect of relative humidity

**Effect of density**:

In a gas medium, the velocity of sound is inversely proportional to the square root of the density. As a result, as the density of the gas increases, the velocity decreases.

**Effect of temperature**:

In a gas medium, the velocity of sound is proportional to the square root of the temperature $v\propto \sqrt{T}$. The velocity of sound in a gas increases as the temperature increases.

The following equation gives the velocity at temperature \(T\):

${v}_{t}=({v}_{0}+0.61\phantom{\rule{0.147em}{0ex}}T)$

Here, ${v}_{0}$ is the velocity of sound in the gas medium at \(0° C\).

For air, ${v}_{0}$ \(=\) \(331\) $m/s$

Hence, the velocity of sound changes by \(0.61\) $m/s$ when the temperature changes by one degree Celsius.

**Effect of relative humidity**:

The speed of sound increases as humidity rises. That is why, during rainy seasons, you can clearly hear sounds from a long distance.