Denise Herzing id'd seaweed, right?
Perhaps there are other ones easy to identify through existing sub-sea-level candid camera videos: hey, there's a [food they eat], let's go over there; help / danger, there's a [thing they fear]; I forgot my [phone / wallet / keys] in my other pair of pants, brb...
> we struggle to determine who produces the sound
What about based on signature whistles for addressing one another? It looks like there's a good amount of info on how they use it, so that could help, right?
> it is a cacophony
What about looking for only "vocal copy" instances between individuals to use as markers?
Signature whistles are tricky, and not everyone agrees that they are actually a thing. There was a recent study done in Israel where dolphins appeared to be using signature whistles of dolphins who died some time ago. It could mean that either signature whistles are not what we think they are, or that dolphins have routine conversations about their dead companions.
Oh, that's not very helpful..
> we do not know if dolphins indeed label things in their natural communication system
I believe we'd need to start with that as a basic assumption for how language works to begin with. How does that assumption seem to you?
> dolphins appeared to be using signature whistles of dolphins who died some time ago
I guess they probably talk about loved ones even when they're not in the same "room", same as us.
> Signature whistles are tricky
"Signature whistle" seems like an awfully complicated way to say "name".
Many researchers have already done that, i.e. using video and audio for sound analysis, and here we are,60+ years later, still do not know the function of even a single call, apart, of course, from signature whistles and echolocation. This is a non-human communication system, 25 mln years in the making by creatures who rely on sounds in ways humans never will.
When we study cetaceans, we struggle to determine who produces the sound, who responds, even tagged animals are problematic, because the sound could be made by someone next to them. In large pelagic pods, it is a cacophony, they chat all the time and never shut up. It appears that at least in dolphins, whistles could be more of a long distance signals, but pulsed ones, like burst pulses, are more of a short distance signals, for those who are close by.
But make no mistake, some information is being transmitted, we know that. The Bastian experiment with all its flaws was first to demonstrate it,and it has been replicated too. Some researchers are not entirely convinced, but it is definitely a very interesting area to explore.