A couple of items that may be of value to you;
1) The legends of diving : Sea Sabres Signaling s System ( Google It)
(This was the very first UW signaling system developed by the Sea Sabres dive club in 1954, developed by an LA Co UW instructor popularized by LA County UW Instructors Association adapted by US Navy, NAUI and later PADI )
2) Bonnie June Davis, (LA Co UW instructor ) UCLA dissertation: Underwater audiology
( Explores all methods of UW sound communication as well as a review of visual communications )
3) Vintage diving UW communications before the popularity of exposure suits and organized diving
good luck with your event
SDM