Abstract: In the space-time diagram，use the space-time lines to describe the movement of the static sound phase and the observer，and the intersection of two lines means the observer receives the sound signal. Combining mathematical graph，we analysis to deduce that formulas of the Doppler effects，those are not only associated with the speed of the observer to the sound source，but also related to the position of the observer to the sound source

Key words: Doppler effects, position of observer to sound source, non-collinear, space-time diagram