There is increase in the sounds frequency, light or some other wave as there source or observer move towards each other called doppler effect.

So if we talk about doppler effect in sound so it is said as when sound object moves towards the listener, frequency of sound wave increases which is concluded to be the higher pitch. In the same way the sound object is away the pitch gets decreased, this is doppler effect or doppler shift in sound.

In the prospective of light so light doesn't gets any medium to travel so doppler shift for light travelling in vaccum only depend on the relative speed of source.