Mach number a small area around the object's leading edge. (Fig.1b) Fig. 1. "Mach number in transonic airflow around an airfoil; M < 1 (a) and M > 1 (b)." When an aircraft exceeds Mach 1 (i.e. the sound barrier), a large pressure difference is created just in front of the aircraft. This abrupt pressure difference, called a shock wave, spreads backward and outward from the aircraft in a cone shape (a so-called Mach cone). It is this shock wave that causes the sonic boom heard as a fast moving aircraft travels overhead. A person inside the aircraft will not hear this.
Mach Song population segments not reached by their media partners. On certain issues, Mach Song Media mobilizes local faith and community organizations to reach deep into their constituencies. So far they have worked with over 200 such organizations on various issues and have the capacity to reach 1,000 faith and community organizations in the Vietnamese communities across the US. "Boat People SOS" has invested over 1 million dollars to develop its own network of Vietnamese-language mass media. This network includes Mach Song monthly publication, Mach Song radio programs and Mach Song television programs. If necessary, Mach Song can readily increase the circulation