1. Military Sonar and Whales
By: Joe Gasper

2. What is Sonar?
Sonar is originally a acronym for sound navigation and ranging
Sonar is used to detect other sea vessels, and to communicate between those vessels
Also sonar is used for navigation

3. Two Types of Sonar Active Sonar Passive Sonar
When sounds are emitted in pulses, and listing for echo's
Passive Sonar
Basically used for detecting noise made by other vessels

4. Active Sonar
Active sonar can detect vessels that are to quiet to be picked up by passive sonar
Active sonar is also used to detect marine mammals such as whales
Also 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 Sonar
Passive 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 whales
It is usually beaked whales beached
Beaked whales are mainly affected by the active sonar

7. Difference in Hertz
Many military’s are now focusing on new types of sonar
Military’s are testing and finding that low frequency sonar are not affecting, or stranding the beaked whales
This may led to a compromise between the military and environmentalists trying to protect the whales

8. Hertz Measurements
Low frequency sonar is different from mid frequency sonar
Low 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 whales
Four 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 examine
When they were performing the autopsies they found two problems

12. Gas Bubbles in Blood Vessels

13. Hemorrhaged Vital Organs

14. References http://medinfo.psu.ac.th/pr/MedBoard/Img/20100216110043.jpg