South Tampa mystery: Where is the sound coming from? Neighbors investigate

LEILA FADEL, HOST:

People in South Tampa, Fla., have been hearing a noise that sounds something like this.

(SOUNDBITE OF BASS PULSING)

FADEL: Some residents say it wakes up their kids and shakes their windows. Others can barely hear it. As NPR's Nina Kravinsky reports, what's making that sound is a mystery.

(SOUNDBITE OF BASS PULSING)

NINA KRAVINSKY, BYLINE: South Tampa resident Sara Healy describes the sound as more of a feeling.

SARA HEALY: If you've ever been close to a subwoofer or something at a big concert, you just feel that vibration, you know, in your core.

(SOUNDBITE OF BASS PULSING)

KRAVINSKY: Healy leads a Facebook group of area moms who are desperate to figure out where this vibration is coming from.

HEALY: It's a big deal when it happens because everybody all the way across the peninsula, from north to south, east to west, they hear it, or they hear something. And people just kind of get on there and compare notes.

KRAVINSKY: On Facebook, the moms speculate. Maybe it's a party barge in the bay. Maybe it's secret testing at the nearby Air Force base.

JAMES LOCASCIO: It's unknown, and it's unnerving. It's spooky. It's in your house at night. You feel like the walls are vibrating.

KRAVINSKY: That's James Locascio. He's an underwater acoustics expert Healy has teamed up with to try to figure out what's going on.

LOCASCIO: It's an urban mystery in this case. And so an investigation is always fun for most people.

KRAVINSKY: When he first heard about South Tampa's mystery, Locascio suspected right away the sound was coming from underwater, specifically from a specific kind of fish. It's called the black drum fish, and as part of their mating process, they flex a special muscle called the sonic muscle against their swim bladder.

LOCASCIO: The swim bladder is the drum. The sonic muscle is the drum stick.

KRAVINSKY: When a bunch of black drum fish get together during mating season, the sound can get loud enough to hear from on land.

(SOUNDBITE OF BASS PULSING)

KRAVINSKY: Sara Healy has raised more than $2,000 on GoFundMe so that Locascio can conduct his investigation. He wants to put his recording equipment underwater to figure out if the mystery sound really is a bunch of frisky black drum fish. And neighbors on the shore will take notes on what they're hearing.

LOCASCIO: From my perspective, engaging the community and having a citizen science opportunity, it can be something that just opens up more information about what's going on right in your own backyard and within your community.

KRAVINSKY: And maybe, just maybe, it'll shed a little light on what's going on at the bottom of the bay.

Nina Kravinsky, NPR News. Transcript provided by NPR, Copyright NPR.