How does a radio wave differ from a sound wave? A radio wave is a longitudinal wave that travels at the speed of light, whereas a sound wave is a transverse wave carried by air that travels at the speed of sound. A radio wave is an electromagnetic wave that travels at the speed of light, whereas a sound wave is a wave carried by air that travels at the speed of light. A radio wave is an electromagnetic wave that travels at the speed of light, whereas a sound wave travels at the speed of sound through air or another elastic medium. A radio wave is an electromagnetic wave that travels at the speed of sound, whereas a sound wave is a wave carried by air that travels at the speed of sound