NAudio - How to change the frequency at runtime (doppler)

Question

I would like to know if there is a way to change the frequency (step) and sound volume during playback in NAudio . I would like to simulate the Doppler effect . The observer is in the middle and does not move. As long as the moving object goes to the observer, his “voice” has one frequency / step , later when, when he passes the observer, he has one more frequency / step .

The green circle is the observer, and the smaller blue circle is the moving object. When the coordinates of the objects x coincide with the coordinates of the observers x, an event occurs that should change the step / frequency.

I want to play the same sound , with only 2 different frequencies , while the sound continues to play. Something like a sudden step shift. I read that pitch shifting is not supported in NAudio, though.