The speed of sound is 340 m/s (in air)
You can hear sounds with a frequency in between 20 Hz and 20 kHz
Sounds is a form of energy, like light, heat or electricity.
The speed of sound depends on the medium through which it travels
(air = 343 m/s, water = 1400 m/s, steel = 6000 m/s). It needs matter though, so it will not travel through a vacuum.