Changing Pitch as you walk by sound?

I was wondering how to do a sort of doppler effect, but that is not dependent on speed. For example when you are standing at the source of the sound the pitch is it’s normal sound, but as you walk away from the source, the pitch begins to bend or go down? So in short, the pitch of the sound is changing based on you and the distance to the object, not relative speed. Any help would be appreciated!