Thursday, January 17, 2008

Ban High Power Active Sonar

Steve at YDD has a post up about Bush waiving the restrictions on the Navy from using High Power Active Sonar in coastal waters. You can read about it there. I am just going to repost my comment to his post here more or less.

The big issue here is with the high power active sonar and why the Navy thinks it is necessary. It is used to do long range scans and depending on water conditions can reach out hundreds of miles. To the marine mammals who have acute sensitivity to sound it can have disastrous effects by basically deafening them to the low level sound they use for survival. In addition to the deafening they may upset the balance mechanisms in the inner ear and cause them to be unable to determine up from down when they are on a deep dive that doesn't have visual clues.
I spent quite a bit of time in the passive sonar world just listening to ocean sounds and with our equipment, that was probably not as sensitive as a whale's, we could "whale talk" from hundreds of miles away.
The high power sonar needs to be banned completely.

Info: There are two kinds of sonar Passive and Active.

Passive sonar just listens with sensitive underwater microphones to whatever noise is running around underwater. The U.S. has "listening" posts strategically placed around the world that listen in on the underwater world, mostly listening for submarines. You had a bit of exposure in the "Hunt for Red October". The tools used are very sophisticated and by breaking down the sound produced by a propeller (cavitations) using what is known as a "Fast Fourier Transform" you can readily identify a specific propeller and hence the ship it is mounted on.

Active sonar is where you "ping" and then listen for the reflection or echo as the emitted "ping" bounces off underwater objects. Normal sonar only has a range of about 10 - 20 miles depending on ocean conditions. High Power Active Sonar uses tremendously loud "pings" to look out hundreds of miles or deep into the ocean.

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