Bianca Garcia

Almost 80 years ago, an unidentified scientist pressed record on a dictation machine.

Researchers then were sailing Bermuda, testing sonar technology.

When they heard something, they didn't recognize.

But they kept recording.

Archivist Ashley Jester found the disk in the Woods Hole Oceanographic Institution's collection.

Her team identified the sound, humpback whales.

According to Jester, it's the earliest sonic record of whale song.

For NPR News, I'm Bianca Garcia in Boston.