Too right about wearing a hoodie - does nullify the verberations considerably. Nothing like listening underwater, be it the sound of quiet when something menacing approaches, the sound of some dudes on Rebreathers having a laugh at your expense as they pass by and the sound of a dive buddy trying to sneak up behind to either peg you or hitch a free ride.
I know Traffic Controllers rely upon a 'Night Wand' and the motion for SLOW DOWN is a progression of Up to Down.
I enjoy Night Dives, especially when you have colourful light beams entering the water from above (street, work, shop lights) but I find the communication facet of a night dive frustrating. Indeed, if it isn't the minimal options of torch manouvers and the awkwardness and time consuming use of the slate then it is the price tag of a Full Face Mask Comms with the hope your Buddy(s) will have/use one.
Just drifting along with whatever is current.
Currently I'm reading : The Art of Innovation by Tom Kelley.