00:03:35.080And because these thrums appear to have individual nuances to them, we can sort of track this, how this one, as it's either being pushed by the flood tide or the whales asleep or it's actively pursuing prey.
00:03:46.180We don't often know the behavioral context, but there's something about the nightfall that gets these whales going with these low frequency near infrasound.
00:03:57.260And it took us quite a while of listening and peering.
00:04:00.300And then we needed Joe's extra sharp ear.
00:04:04.080So, Joe, tell us how you track these underwater component down.
00:04:09.420Yeah, well, and it actually wasn't my ear, it was my eye that was able to find it
00:04:13.440because it's easy to hear, like Fred was saying,
00:04:16.940it's really easy to hear the sounds in air.
00:04:21.560And if you look at this image that I'm sharing with you,
00:04:27.840and you don't need to really understand what a spectrogram is and all the details of it.
00:04:32.900It's like a musical score, isn't it, basically?
00:04:35.740In a way, but the important thing, though,
00:04:39.180is that you're looking at the sound pitch, the frequency,
00:04:43.120and it gets higher as you go up on the screen,
00:05:15.860We don't know really how loud it is, but it's just relative to everything else.
00:05:19.620So you can see on the air one, it's mostly black around these lines, meaning that what is not the sound that we're interested in is really quiet.
00:05:29.400but the sound itself is really loud relative to that if you look at the underwater one you notice
00:05:35.620that there's all this light blue and colors all around and that the the line that we're interested
00:05:41.160in which is just above the one on the screen below or the window below in the air is just a faint
00:05:48.660green so on this scale it means that there's very little difference between the sound we're
00:05:53.620interested in and all the other sounds that are being produced in the water so it's really
00:05:58.500difficult to identify these sounds because it's hard to hear when you've got a sound that's just
00:06:04.680barely louder than everything else that's around. And so what we were looking for is this shape of
00:06:13.160the sound in air. And then I started scrolling through the sounds in the water to see if I could
00:06:19.560find anything that looked similar at roughly the same time. And this is an example when we found
00:06:25.600one. And the water one showed up earlier than the one in the air. And that's what we expect
00:06:33.800because the speed of sound in water is much faster than the speed of sound in air. It's
00:06:37.480about four and a half times faster. But if I click on this at the beginning of the air
00:06:42.920sound, I'm sorry, the beginning of the water sound, okay, and then I move over to where
00:06:49.700the air sound starts, you can see that's approximately 1.2 seconds. So the sound and
00:06:57.300water reached the hydrophone 1.2 seconds faster than the sound and air. And the thing that I got
00:07:03.580excited about is that that means we can calculate roughly how far away the whale is without even
00:07:09.640seeing it. We're just using a hydrophone and a microphone. What do you think the whale is saying
00:07:18.380And how do you differentiate a sound like this from other sounds so that you can categorize it or even begin to, I guess?
00:07:30.020And, you know, when we first started detecting these, it's really intuitively pleasing to think about that these are a form of communication.
00:07:39.180And, you know, humpback whales are extremely verbose underwater with their social chatter and their songs and when they're screaming at the herring to chase them up to the surface.
00:07:49.820And so when we hear these coming through the air, we're already really inured to thinking that these are very communicative species.
00:07:59.700And this has got to be some crazy, more, you know, perhaps some sort of long range rumble.
00:08:03.860I've found some food over here, or we've got some metal, some killer whales, keep your distance, or we've got some metal, some killer whales, get over here, need your assistance.
00:08:14.380But, you know, so when you assume communication, it presupposes, there's just certain predictions, there's certain corollaries of communication.
00:08:24.700If a signal's being used for animals to talk, well, then you expect there to be kind of a conversation of a back and forth, you know, a volley of like, hey, what's going on?
00:09:38.260It doesn't mean they're not doing it, but we just don't have any.
00:09:40.820I mean, is there sound receptors on the blowhole?
00:09:42.620I mean, what's going to be above the water?
00:09:43.940We know that the air-water interface, the surface of the ocean,
00:09:46.320is almost like a perfect mirror in terms of just a very small fraction
00:09:51.100of the sound can get through that air-water interface
00:09:54.380because water is 800 times denser than air.
00:09:56.940sound just, sound wants to stay underwater and it bounces back. And then when the air sounds,
00:10:02.500they're having a really hard time getting into the water. And so, um, when we, when we, when we
00:10:08.280just, we just couldn't find these, the underwater component until Joe had his, had his, um, expert
00:10:13.960eyes. Oh, we are picking up a little bit of ghosting there. It's something is being produced.
00:10:18.280So if it was communication, you know, and if it's especially for a long range communication,
00:10:22.820that signal should be strong. You know, it should have some power. It should be able to transmit
00:10:28.000through wave slap and snapping shrimp and even, you know, vessel noise. And so we're just not
00:10:34.380seeing that. So that kind of militates against the notion of communication. And also the fact
00:10:40.940that they just appear to originate from these animals kind of randomly. You know, their breathing
00:10:45.380is sort of a random thing and the thrums are produced by a raspberry type puckering of the
00:10:50.460blow hole and that is associated with a breathing cycle and breathing is something that animals can
00:10:57.540do it's certainly under conscious control and certainly cetaceans but oftentimes it's just
00:11:01.600it's just um it's your breathing is responding to your uh socializing or your pursuit of prey
00:11:09.360and then you you're down below and you're swimming around and blowing bubble nets and lunging and
00:11:13.440engulfing and then oh got to go back to surface to breathe and so you're you're going up to breathe
00:11:18.040And then you have these potentially incidental sounds produced during breathing.
00:11:23.200And so once you get a bunch of animals out pursuing prey independently, they're kind of random to each other.
00:11:28.500And we don't hear these sounds clustering in time and space suggestive of communication.
00:11:34.580And then we did our darn tootin best appear into the below the human hearing level by playing with various satellite dishes and various parabolics,
00:11:45.120converting them to concentrate more sound energy on the microphone so we could see if there was
00:11:50.940an infrasonic component and i haven't found that either and um so we're science often works by not
00:12:00.100being able to definitively show that something is true but that um you've been able to show that
00:12:06.880your other um ideas about mom say mom calf pairs well everybody seems to be doing this so it's not
00:12:12.240just mom and calves. So probably not that. And so you started eliminating notions until
00:12:16.100last individual standing, last one standing. And, um, so some sort of, um, um, maintenance
00:12:23.160activity as we respected on earlier. And Joe, what are your thoughts?
00:12:29.700Well, and I'm, I'm not the biologist, but I, I do think that it, that it could still be
00:12:36.200indicative of emotional state um you know that it's not just they're not just randomly breathing
00:12:44.760and sometimes getting this sound but it could be like fred you and i had and and others had just
00:12:50.780talked about well it could be just where you're having that feeling of just you've you've you've
00:12:57.620had a lot of activity and now you're just relaxing and when and when your body relaxes all your
00:13:03.320little um uh your muscles and your your lips and everything get a little bit more relaxed and so
00:13:10.840when you breathe out you just make that raspberry sound so it could be indicative of that interesting
00:13:16.580yes so it's kind of a kind of a um kind of a or kind of like a groan a groan of satiation or
00:13:22.240contentment um and i kind of get that feeling it certainly sounds like it um the other evening when
00:13:27.860we were um we were reflecting with the residents of petersburg who live out sandy beach road over
00:13:33.240overlooking frederick sound and that was the kind of general consensus that doesn't sound at all
00:13:39.040aggressive it sounds like um something was just accomplished and a sigh of contentment or um
00:13:47.380so yeah and so i mean by the on the other hand it's like um we know that adaptive sounds for
00:13:58.020maintenance in other contexts like with the african hunting dogs that sneeze for maintenance
00:14:02.960of the airway and the sinuses, but they also sneeze as a communication to get their groupmates
00:14:12.400roused for the hunt. And so we just may not have yet sampled the behavioral context where these
00:14:18.960potentially maintenance sounds or background sounds are pressed into service for communication. So
00:14:24.180there's still lots we have to learn, but our initial feedback suggests we don't know what
00:14:30.800the hell's going on can we hear another sound
00:14:34.660so here's a nice um strong one that um it's pretty bold and it um
00:14:47.220it's it's cool i mean so okay so in support of in support of a um potential communication function
00:14:56.560is that not all thrums are created equal.
00:14:59.180We're finding quite a bit of variation,
00:15:00.800and we don't know to what degree that represents
00:15:03.040individual variation, consistent, very identifiable variation,
00:15:06.560or does that represent just changing emotional states?
00:20:52.620And so it's potential that critical sounds like a solicitation for help or an alarm call associated with predators or a bonanza food patch.
00:21:03.680Are we masking those and making it harder for animals to, across the summer months, to just continuously degrading their ability to communicate and feed?
00:21:15.660And so they're leaving to Hawaii with reduced body weight and fuel storage.
00:21:22.120It's all entirely speculation, but you get the point that there's lots of ways we can gain insight into their lives and needs by understanding their communication system.
00:21:36.960Is there another sound that you could play as?