before any beacon is shipped from here its sound output is measured in one of these huge 50,000 gallon tanks. it's lowered into the tank through the floor above. surround by hydrophones, ultrasonic readings are recorded on this computer. this pinger is twa flight 800 which went off the coast of new york back in 1996. this company made the pinger. after it was recover they got it back. this one was found in shallow water but they are designed to function in water as deep as 20,000 feet. what about the frequency? crews at sea picked up a slightly lower frequency than the pinger's standard frequency of 37.5 kilohertz. water temperature can shift the frequency. it's so distinct, right? there's nothing else that would sound like this with this frequency. >> 37.5 kilohertz was selected because it is unique from the background noise in the ocean.