Speed of sound in atmosphere or air varies from 330 meters/sec to 340 meters/sec depending on pressure, temperature, density, humidity etc.
Speed of sound is the speed with which the disturbance (wave) travels in space in time. It is the product of the frequency of vibration of the source and the wavelength of the wave in the medium.
In vacuum the speed of sound is zero.
In solids the speed of sound is dependent on the elastic property (modulus) and density of the substance. In gases it is dependent on pressure and density.