"虎豹雷音(Hu Bao Lei Yin) - tiger leopard and thunder sound" is used in the XingYi system Fajin training. The similiar exhale Fajin sound is also used in the Chinese wrestling. Do you make similiar sound during your Fajin training?

http://www.youtube.com/watch?v=Svz7DB4z1Sc

http://www.youtube.com/watch?v=MJuPvSkbXJY