* Temperature: The speed of sound increases as the temperature increases. This is because molecules move faster at higher temperatures, leading to faster sound transmission.

* Medium: Sound travels at different speeds in different materials. It travels fastest in solids, then liquids, and slowest in gases. For example, sound travels faster in water than in air.

* Density: The denser the medium, the faster the sound travels. This is because molecules are closer together in denser materials, allowing sound waves to transfer energy more efficiently.

* Humidity: Humidity slightly increases the speed of sound in air. This is because water molecules are lighter than air molecules, and the presence of moisture makes the air slightly less dense.

To sum it up:

* Higher temperature = Faster sound

* Denser medium = Faster sound

* Solid > Liquid > Gas (Speed of sound)

* Humidity slightly increases speed in air