The Audiophiles: The mysterious language of blue whales
Stand on the beach overlooking Half Moon Bay, and the sound you’re most likely to hear is of waves crashing against the rocks. But when Roger Bland climbed up there, he wanted to hear what was underneath those waves.
That’s because Bland is an acoustic physicist. He studies sea life by using a series of underwater microphones called hydrophones. That’s how Bland records the sounds of the Bay:
ROGER BLAND: Okay, first of all the ships going by make a huge racket, like a raaarrrr kind of noise, so you have to listen between that. And there’s a lot of time between the ferries. And there’s an amazing spectrum of sort of clunks and gurgles and ratcheting sounds of various sorts.
He also heard whales. Whales of all kinds, but specifically the blue whale, which is the largest known mammal on earth. In this piece from our archives, KALW’s Martina Castro spoke with Roger Bland in his laboratory at SF State, and he explained to her how he went about recording the calls of these underwater giants.
ROGER BLAND: There's an underwater mountain and there are four hydrophones that are placed about 30 feet apart on a cable. The cable comes onshore, varying the average break, and it ends in the Pillar Point Air Force Station – the one that tracks missiles down there, but they gave us a little space to do a little recording and have an internet connection.
MARTINA CASTRO: And so what came back? What did you get out of those two years of recording?
BLAND: (imitating a whale) Mwaaaaaaah! (laughs) Many thousands of whale calls. Also, the fin whale sounds like like an ong! ong!. It was the blue whale that we studied. The sounds they make are indistinguishable and make exactly the same frequency of that moaning. Everything about that is exactly the same. This is not well understood. Not only is it the same frequency of the call, but they repeat this every 126 seconds. And they all repeat it every 126 seconds.
I have to admit the reason we studied this call is because everything else is so complicated, but this particular call is exactly four octaves below middle C. They do that for 20 seconds and then come at it again later for 20 seconds. As a physicist in particular, it seems you need something you can quantify and then maybe that can lead somewhere. And it sort of did with these whales.
CASTRO: And so it was exactly the same, for all of these whales and all of the blue whales that passed through these hydrophones?
BLAND: That's right. No one understands why they would all want to sound the same and how they coordinate themselves over 1,000 miles. Who calls the shots? Is it the biggest whale that says, “Everyone else call like me?” Is it some circuit in their brain that makes them want to resonate with some sound? Because at any moment in our recordings, there are individual whale calls. But there is also a sort of background at 16 hertz from whales all over the Eastern Pacific. They all seem to want to call and seem comfortable calling at the same frequency.
CASTRO: And so it's a total mystery, we have no idea what they are saying to each other?
BLAND: Well, we published an article on this and had the following suggestions: that because this is a very accurate frequency, there's some stuff to do with the Doppler shift. That is also what they do in a baseball game to measure the speed of a baseball. If you reflect radiation off of something that is moving, it comes back at a different frequency. There's another Doppler shift where the female whale might use to locate a male. And this is because, if she swims in the direction of the source, the frequency will be moved up a little bit. So she can swim in different directions, probably sort of oscillate back and forth, and find the direction where the frequency is the highest and locate the male that way.
CASTRO: And that's a theory?
BLAND: That's a theory and I don't imagine it will be proven any time in my lifetime, but it was a suggestion. The reason why the population is low, of course, is because of whaling. People started killing blue whales in the 1920s, when they got fast boats and good harpoons, because the whales could outrun the boats before that. I think they stopped whaling in the '60s and the blue whales have not fully recovered. They are at around 1/20th of their original population.
CASTRO: Why is that?
BLAND: I don't know. We don't know! We don't know a whole lot of things, and that's one of them.
The Audiophiles is a series that brings you some of the most unique sounds in the Bay Area, and introduces you to the creative minds behind them.
This segment of the show originally aired on September 19, 2011.