1. The speed of sound in air is independent of pressure.

2. If we talk about density of medium, speed of sound in solids is greater than the speed of sound in liquids and the speed of sound in liquids is greater than the speed of sound in gases.

So, Speed of sound increases, when density of medium increases.

3. When the temperature of medium increases,the particles of medium collide more frequently and hence the disturbance spread faster.

So, Sound travels faster as the temperature of medium increases.

4. The speed of sound in moist air is greater than the speed of sound in dry air, for the same pressure.This implies that as humidity increases, the speed of sound in air increases.