Marine scientists used underwater microphones, known as hydrophones, to capture the sounds of the deep ocean. Some years ago, scientists found some strange noises captured by hydrophones in the Pacific Ocean. The sound was weak and constant during some times of the day, with intensity a few decibels more than the background level and the normal sound level of the ocean. The strange sound had an intensity of 300 hertz and above, which is beyond the sound intensity of whales other marine mammals.

Scientists have earlier noticed that billions of marine organisms come out of the mesopelagic zone during the night time to the surface for collecting food. The mesopelagic zone is a dark patch in the ocean between the depths of 660 and 3,300 feet. However, the sound was captured for the first time. "It's not that loud, it sounds like a buzzing or humming, and that goes on for an hour to two hours, depending on the day", said the co-author of the new study, Simone Baumann-Pickering, a Marine Biologist at the University of California, San Diego.

The new study revealed that the bizarre sound is created by the upward and downward movements of the organisms during the dusk and dawn. The sound could be dinner bell for these organisms or even the steady grumble of farting of the fish, which are known to release gas when their water depths change. Though it has not yet been found which species make this sound, it is most likely made by small bony fish.

It is being suggested by Baumann-Pickering and her team that the sound might be instrumental in developing ocean food webs and the global carbon cycle. The scientists also believe that the discovery will be helpful in getting a better insight of the deep-sea ecosystem, which still houses several mysteries.