researchers show us the challenges search crews face as they try to hear the ping from flight 370 s data recorder. so this is a hydrophone. we drop an underwater microphone, a hydrophone, off the back of the boat as it moves farther away from a pinger that s already been submerged. and even less than 100 yards away, the ping starts to fade. distance isn t the only problem out in the indian ocean. there are other noises competing with the sound of the pinger, like sea life. one dolphin species sounds like a black box pinger and this is the sound of rain underwater. let me get away from the loudest part of the boat, so i can show you one of the biggest obstacles that searchers have in the open sea. just ship noise. even here, listen to how loud it
so, right around here. hopefully there s not a lot below that, where they are actually hearing this device. hopefully it s not at the deepest point. all right, we are going to continue to look now beneath the surface. thank you very much, as we have been mentioning, surfaces may be scouring a specific part of the ocean floor, and some of that searching will involve sonar using sound waves to map out the bottom of the ocean. we will look at the technology that makes it all possible. the idea of searching the ocean floor is a huge undertaking. we want to show you a different in the couple of technologies that are likely being used in the indian ocean. and he is going to show us first when a hydrophone does. exactly, this is a hydro phone, it s an underwater microphone. it s a device like this. either strung together in a tail that they tow behind the boat or dipped over the side, or dipped
underwater microphone, a hydrophone, off the back of the boat as it moves farther away from a pinger that s already been submerged. and even less than 100 yards away, the ping starts to fade. distance isn t the only problem out in the indian ocean. there are other noises competing with the sound of the pinger, like sea life. one dolphin species sounds like a black box pinger, and this is the sound of rain under water. let me get away from the loudest part of the boat, so i can show you one of the biggest obstacles that searchers have in the open sea. just ship noise, even here, listen to how loud it is. there are, at a minimum, 15,000 ships on the world s oceans on any given day, creating even more obstacles in a search that s already daunting. rosa flores, cnn, narragansett
the malaysian airliner mystery now crosses the four-week mark with a new question about the pilot s flight simulater. on the water, two vessels are using special sonar technology to try to detect pings from the jet liner s flight recorders before their battery runs out. one of the ships is using an underwater microphone from the u.s. navy. up to 13 planes are part of today s operation conducting a visual search for remnants of the missing jet. no trace has been found four weeks after it took off from kuala lumpur for beijing. nick raja is live with the investigation, and erin is live in perth. erin, let s start with you.
oceans. richard quest is a cnn aviation correspondent and arnold carr joins us. how can they be sure the sound is from a pinger, greg? we clearly need more information. i would like to see what kind of hydrophone which is the instrument you hear these things on. an underwater microphone. see which type of hydrophone they are using. a readout and our sonar expert here is probably better equipped to actually look at that. you have to keep in mind there is a lot of sources, potential sources, in the world s oceans for the frequency range. especially if it was heard once. i spent a lot of time looking for sounds in the ocean. i cannot tell you how many times i thought i heard something. you don t hear it.