You're hearing these dolphins
use high-pitched clicks and whistles
to navigate a world of obstacles, danger, and prey
with their pods.
But these spirited signals are in jeopardy of being drowned out
as the ocean gets noisier every year.
PAUL: When we saw those dolphins, and
put the hydrophone in the water, I almost cried.
It was the first time in my life I could hear their voices.
With more than 500 miles under his belt,
Ben Lecomte and the crew are more eager than ever
to get his trans-Pacific Swim back on track
and continue raising awareness for ocean health.
They will then resume the protocol
of collecting 8-12 hours of underwater audio each night,
in an effort to build the most comprehensive
soundscape of the Pacific Ocean in history.
PAUL: The first goal for us is to have this photography,
this sound postcard of the ocean.
This data could help scientists determine
how crowded the ocean is with marine mammals,
and how they're affected by man-made sounds,
like shipping traffic.
HERVE: The more you have sounds in the sea, in the oceans,
the less the animals can communicate
between each other, so the less they meet.
The less they meet, the less they reproduce.
The team is using a calibrated hydrophone,
a microphone that picks up specific frequencies
within a 20-km radius underwater.
It can detect everything from the playful clicking of dolphins
to the sound of sperm whales hunting.
HERVE: A "soundscape" is a recording of a multiplicity of sounds.
Recording these sounds will create which scientists call an "acoustic transect."
HERVE: Each night, we're recording from sunset to the morning
with the same hydrophone, at the same position, from the same boat
so it makes something like 3,000 hours of recordings.
When the team receives the data, they feed it through artificial intelligence models
they've developed that can recognize the calls, clicks, and whistles
of a number of different cetacean species.
Anthropophony are the sounds from human activities;
biophony are the sounds from biological activities;
and geophony is the sounds from the wind, and the rain, and the tectonic.
So our work is to use what we call the machine listening system.
We train this machine on the soundscape of cetacean sounds,
and then they are able to index, or categorize, classify
sounds from many different species.
This catalogue could map population densities of whales and dolphins
as the crew travels east, and may even pick up some
surprising signals along the way.
HERVE: During the Cold War, some did record what they called a "Big Duck."
They didn't know at all what it was, and they thought
it was a special submarine from the East Bloc.
But it was a minke whale.
And this minke whale has been completely described
only 10 years ago.
If audio evidence can reveal where cetacean superhighways cross the Pacific,
then policymakers can develop "quiet zones"
to help alleviate the stress of human noise on wildlife communication.
This is why continuing Ben's mission to highlight ocean health is so important.
HERVE: The best outcome of The Swim is to demonstrate
that there is a continuity alive in the ocean.
It's a complex habitat. It's full of life.
And the density of this life will be depicted by these recordings.
PAUL: The water is not empty.
It has been very surprising to see how much life there is.
We have our everyday whale... like at the point where we drop Ben,
we always have a whale waiting for us.
So to enter in some kind of relationship with this world
and with all these mammals and all these creatures in the water....
Learning from them by listening is very, very touching.
Be sure to visit Seeker.com/theswim to read daily updates from Ben Lecomte,
track his progress in real time, and watch more videos
about the science happening onboard Seeker.
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Thanks for watching.