perspective when we re talking about teeny tiny microphones looking for teeny tiny black boxes. they create walls. sound can baounce off it and no make it through it. put a sub right above or below one of those, and they re shooting sound to find a sub they can bounce off the therm aa thermales and not see the sub. if the toe pinger locater is being towed behind the vessels in question, they have to be exactly in the right thermal layer in order to detect something? more or less. there s one layer that travels the whole ocean from 2,000 to 4,000 feet. it goes up and down. it s a deep sound channel that sound can get caught in. propagate for miles. the sound can get caught in there and not make it through. parts of it can make it through. that s why that pinger is being deployed. they re towing that pinger down into about 3,000 feet of water where they can actually get into that zone and maybe even pick up