Hello Len
There was a large destroyer at the Bury Show last weekend and it had a similar sound system.
It was an I-POD with recorded live sounds taken off the net. It was connected to two giant speakers and played a programme of sounds……like……Gas turbines…….ships sirens……..Ack Ack guns……Bofors….machine guns…………..and was quite novel…………and a crowd pleaser!
Bob