Eerie noises kept coming from the deepest point on Earth for years — scientists finally know what it is

Deep beneath the surface of the ocean, sounds travel freely, but identifying them can take several years. In 2014, researchers conducting an acoustic survey near the Mariana Trench off the coast of Guam picked up strange, low-pitched noises followed by metallic echoes. Scientists later termed these mysterious sounds "Biotwangs," as reported by BBC. At first, experts suspected they might be whale songs, but the exact species of the whale remained unknown. After further study, researchers finally traced the sounds to Bryde’s whales—fast-moving marine giants that thrive in warm, tropical waters.

The National Oceanic and Atmospheric Administration (NOAA) experts turned to artificial intelligence for solutions. AI technology sifted through over 200,000 hours of ocean recordings in search of hints. According to scientists, these unsettling whale sounds provide a means for the animals to locate and interact with one another while navigating the vast undersea environment. As reported by Newsweek, the co-author of the study, Ann Allen, who is also a research oceanographer at NOAA Fisheries, said, "Seagliders are autonomous, so there were no visual observations to clue the researchers in as to what might be the source of the weird, mechanical-sounding call."

Allen continued, "But given that similar previous mechanical mystery sounds were found to be produced by whales, they hypothesized that it could be a baleen whale call." The researchers also wrote, "With nine confirmed Bryde's whale sightings in conjunction with sonobuoy recordings, we demonstrate that the previously identified Biotwang call is made by Bryde's whales." They added, "Biotwangs were observed in association with a single whale, mom-calf pairs, and groups up to four individuals with and without a calf. The only Bryde's whale sighting without Biotwang recordings was of the largest observed group (five animals), which was the only sighting of multiple individuals that did not contain a calf."

The researchers were uncertain about the exact meaning of these calls for the whales. Allen pointed out, "We have no idea what this particular sound is used for yet. Other whales use their vocalizations for mating displays, feeding coordination, socialization, and as contact calls as they migrate." Experts claimed to have heard Biotwangs all year long, whether close to individual whales, mother-calf pairs, or small groups. This implies that the noises could work as a contact or social call, enabling whales to maintain communication over great oceanic distances. Another interesting fact is that the scientists found these unusual noises were primarily heard in the Northwest Pacific, suggesting that the noise was only coming from a certain population of whales.

After searching through years' worth of underwater recordings to determine where the mysterious sound had previously been heard, the experts were able to pinpoint its origin. The movements of the responsible species were mapped out with the help of their analysis. Meanwhile, these whales are named after Johan Bryde, a Norwegian consul who was involved in the establishment of South Africa's first modern whaling station. Bryde's whales are much calmer than humpback whales, who perform magnificent displays by breaching and slapping their fins. Given their propensity to remain underwater, sightings are uncommon, which contributes to their mysterious aura.