I am currently writing a couple science-based articles, one of which is focused on noise pollution which has a good dose of info on the nature of sound in the sea, some comments on natural sources of ambient marine noise, etc.
I am including some stellar online resources and can’t help but post a few of these here as I go along.
There is a spectacular website called “Voices of the Sea” with recordings of multiple species of cetaceans and pinnipeds available to listen to. The website is visually very slick and the sound files play effortlessly. There are also various videos with more info on species. I also like how they show the sound spectograms while the calls are playing to let you know the frequencies of the sounds you are hearing. (Just an FYI, it is somewhat likely at least a couple of these calls have undergone some audio manipulation to bring them within the range of human hearing….).
Cornell University, who hosts a well-known bio-acoustics program, hosts a Right Whale Listening Network , and their research has been essential in the study and protection of these very endangered animals.
During a right whale ecology cruise I was part of, I’ve also been able to view the deployment and retrieval first hand of some of their pop-bouys which are used for acoustic research. It’s pretty interesting business. The buoys are deployed with sandbags to keep them weighted down. They are retrieved at night (for the sake of making them easier to find, once at the surface they employ a sort of strobe light). Once the ship is close enough, a researcher sends them a “burn” signal which is a communication with the buoy telling it to release anchor (i can’t quite remember the specifics of hot the buoy does this…) and pop-up to the surface. The ship then unceremoniously navigates close by and they’re grabbed with a long hook (think of the kind of hook you’d envision really terrible preformers being pulled offstage with). On the same cruise I was also able to hear some recordings of Atlantic white-sided dolphins captured via hydrophone.