That has been on Tonystrains website for a while, I acually printed it out. It is also very helpfull for understanding sound waves.
Truck.
Here is a fairly new document on this subject. Does not cover all but might shed some light for those who wonder.
http://qsisolutions.com/pdf/loco_acoustics_design.pdf
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.