For the past few weeks, an ominous sound has been emanating from a mysterious source in Bay Ridge, Brooklyn.

It’s hard to describe “the Bay Ridge bing,” which got its nickname from New York City Councilmember Justin Brannan.

"You know those bells at a carnival, where you swing the little mallet and you hit the top, if you’re strong enough to hit the bell?” said Brannan by phone. “It’s sort of like that, over and over again."

“I normally hear the sound in the mornings,” said Britt Ancona, a lifelong Bay Ridge resident. “The first time I heard it, it was around 8:30 a.m. on November 1st. It was an eerie, perfectly-timed bing sound that seemed like it was coming from the sky. For me, there was no one direction where you could say it was coming from. It was just there.”

“It’s a metallic sound, repeating in a steady, thrumming beat,” said another Bay Ridge resident, Jennifer Kruger. “It’s both loud and muffled, like it’s something loud happening far away.” Kruger took this cellphone video documenting the bing; you may be able to hear it better with headphones:

Earlier this week, Brannan tweeted that the mystery is solved. He says the sound is coming from this multi-pronged, terrifying-looking, elevated boat—a liftboat—that’s been spotted off the shores of Bay Ridge.

So whose boat is it? The Coast Guard pointed WNYC to Verizon, which contracted the vessel. A Verizon spokesperson explained the boat was boring holes as part of exploratory work being done to expand the network of fiber cable that connects Brooklyn and Staten Island to New Jersey and the rest of the country. (So to answer the big questions: no, this is not an offshore oil drillship. And yes, this means Verizon is looking to expand services like FiOS in Brooklyn and Staten Island.)

“The work was completed on Monday evening and the barge is expected to leave at the next high tide,” said David Weissmann, public relations manager for Verizon, by email on Tuesday afternoon.

“As to the reported sounds,” he continued, “it is possible that they were a result of the work being done, but we can’t say for sure.”

But wait—there’s a wrinkle in this timeline: Weissmann says Verizon’s work began on the Staten Island side last week and on the Brooklyn side this past Saturday. That doesn’t line up with observations from November 1st, when Ancona and many other people in the neighborhood claimed to have noticed the “bing” sound.

“We’re sorta doing deduction here,” said Brannan, explaining that people saw the boat and correlated it with the sound. “But I’ve watched enough ‘Law and Order’ to know you could be in for a surprise ending at some point.”

Listen below to hear the story, and the “bing” sound, from WNYC. And Bay Ridgites, tweet at @WNYC or @shubasu if you hear the sound again! Now that the boat has moved on, your observations will help us solve the mystery of whether the “bing” is truly connected to the Verizon vessel.

Shumita Basu is a host, producer and reporter in the newsroom. You can follow her on Twitter @shubasu.