Hi yall, As you are surely aware, DirectSound does not support sound propagation delays (yet!). For example, the sound of an aircraft at 5Km will take approximately 5,000/MACH_1 = 14.7 seconds before it can be heard (Sound of speed = MACH_1 = ~340 m/s). I''ve been tring to come up with an algorithm that would take this parameter into account. I was wondering if anyone whould have any ideas. A simple method would be to start the sound source 14.7 sec after the sound instance is created. But this does not make sense. Although it effectivelly causes a delay, you also loose the sound distorsions it has generated during that time. Suppose my aircraft starts with a velocity of MACH 0.5, then accelerated to MACH 1, then returns to MACH 0.5, and all done withing 14.7 seconds. Then the doppler shift effect during that time (including the sonic boom) will not be heard since I am skipping over this time. Later,