2 What is Sonar?Sonar is originally a acronym for sound navigation and rangingSonar is used to detect other sea vessels, and to communicate between those vesselsAlso sonar is used for navigation
3 Two Types of Sonar Active Sonar Passive Sonar When sounds are emitted in pulses, and listing for echo'sPassive SonarBasically used for detecting noise made by other vessels
4 Active SonarActive sonar can detect vessels that are to quiet to be picked up by passive sonarActive sonar is also used to detect marine mammals such as whalesAlso active sonar detects marine mammals in shipping lanes, or in high sound pressure zones.These high sound pressure zones are usually used for military exercise
5 Passive SonarPassive sonar picks up sounds using electronic listening equipment.A target can be detected by the noise it makes from its machinery, the propeller, or the sound of the water passing around the vessel as it travels.
6 What Type Causes More Harm? The active sonar is what causes the problems for the whalesIt is usually beaked whales beachedBeaked whales are mainly affected by the active sonar
7 Difference in HertzMany military’s are now focusing on new types of sonarMilitary’s are testing and finding that low frequency sonar are not affecting, or stranding the beaked whalesThis may led to a compromise between the military and environmentalists trying to protect the whales
8 Hertz MeasurementsLow frequency sonar is different from mid frequency sonarLow frequency sonar puts out between 100 and 300 hertz, whereas mid frequency sonar puts out between 2,000 and 10,000 hertz
9 How Military Sonar Affects Whales Why are whales beaching themselves from the sonar?Researchers believe that the sonar causes decomposition sickness or “bends”This is common among scuba divers that rise to the surface to quick
10 Research Behind the Stranding In 2002 there were autopsies preformed on stranded beaked whalesFour hours after a military sonar test started the beaked whales started to beach themselves
11 What Did the Autopsies Reveal? The researchers had eight beached specimen to examineWhen they were performing the autopsies they found two problems
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