On a recent trip to Florida, we went to see some manatees at a “lagoon” just north of Palm Beach. (More info and a pic of one of the manatees we saw here.) They had a little marine museum set up, too, and one of the exhibits had a touch screen and a bunch of old phone receivers. You could pick up the phone, touch a button on the screen, and listen to underwater recordings of various manatee calls, grunts, and sighs. We listened to this particular recording much more than the others.
