anchor: Source:setVelocity
  Sets the velocity of the Source.
  
  This does '''not''' change the position of the Source, but lets the application know how it has to calculate the doppler effect.
  Source:setVelocity( x, y, z )
  x number The X part of the velocity vector.
  y number The Y part of the velocity vector.
  z number The Z part of the velocity vector.