train horns
#11
#12
For the best/loudest effect, underneath propagates sound reflection off the road, reinforced by the bottom of the truck:
http://stuff.is-a-geek.net/PhotoAlbu...cs/CTD_165.jpg
http://stuff.is-a-geek.net/PhotoAlbu...ics/CRD_61.JPG
http://stuff.is-a-geek.net/PhotoAlbu...cs/CTD_165.jpg
http://stuff.is-a-geek.net/PhotoAlbu...ics/CRD_61.JPG