War Games Set to Begin Today in the Pristine Gulf of Alaska

"Today the US Navy plans to unleash 6,000 sailors, soldiers, airmen, Marines and Coast Guard members along with three Navy Destroyers, 200 aircrafts, untold weaponry, and a submarine to converge in war games in the Gulf of Alaska .... Concerning is also the use of active sonar, which is used to produce an underwater map by bouncing intense sound waves off of the ocean floor. The sound is extremely loud and distressing; at 235 decibels it is about a thousand times louder than the noise from a jet engine. It is believed this causes the whales to flee to the surface in attempt to get away from the noise. Disoriented, they surface too fast, and can die of the bends."

War Games Set to Begin Today in the Pristine Gulf of Alaska

So the Navy will dump a bunch of toxins in the water in the middle of the fishing season, blast the sonar proven to kill whales. They don't care about the public's opposition. Seems they're not fully disclosing their plans. Could this be beginning of the end for the Alaskan fishing industry? Seriously nuts.

I feel sad for the marine life in the area. Most likely will result in whales dying. Sad state of affairs this world is in.

originally posted by: LaBaleine
The sound is extremely loud and distressing; at 235 decibels it is about a thousand times louder than the noise from a jet engine.

A jet engine is about 140 decibels. A thousand times louder? I don't think so.

The Navy has been exercising in the Gulf of Alaska for years. In 2009 they expanded the exercise area, roughly doubling it.

Yes, it's upsetting and most likely will result in lots of whale standings. I hope the carcasses end up in public beaches with lots of witnesses. a reply to: w8tn4it

Yes they've been exercising perioidically every two years since 1994, but in 2011 the scaled scope of the excercice and were authorized to use sonar for the first time. However, it was NOT used, as the Navy used an alternative plan of action that only used explosives. This will be the first year they will use sonar in the Gulf of Alaska. a reply to: Zaphod58

I dislike what many naviess do to the sea life around our world but i think we do have to bear in mind the item below so that we dont get facts wrong when discussing the harm to sea life from noise
the sound levels given in dB in water are not the same as sound levels given in dB in air. There are two reasons for this:

Reference intensities. The reference intensities used to compute sound levels in dB are different in water and air. Scientists have arbitrarily agreed to use as the reference intensity for underwater sound the intensity of a sound wave with a pressure of 1 microPascal (μPa). However, scientists have agreed to use as the reference intensity for sound in air the intensity of a sound wave with a pressure of 20 microPascals (μPa). Scientists selected this value in air because it is consistent with the minimum threshold of young human adults in their range of best hearing (1000 -3000 Hz)
Densities and sound speeds. The intensity of a sound wave depends not only on the pressure of the wave, but also on the density and sound speed of the medium through which the sound is traveling. Sounds in water and sounds in air that have the same pressures have very different intensities because the density of water is much greater than the density of air and because the speed of sound in water is much greater than the speed of sound in air. For the same pressure, higher density and higher sound speed both give a lower intensity.
The result is that sound waves with the same intensities in water and air when measured in watts per square meter have relative intensities that differ by 61.5 dB. This amount must be subtracted from sound levels in water referenced to 1 microPascal (μPa) to obtain the sound levels of sound waves in air referenced to 20 microPascals (μPa) that have the same absolute intensity in watts per square meter. The difference in reference pressures causes 26 dB of the 61.5 dB difference. The differences in densities and sound speeds account for the other 35.5 dB. A 60-dB difference in relative intensity represents a million-fold difference in power.

When reporting sound levels, it is important to not only say "dB" but to also add the reference level. This is often written as "dB re 1 μPa" for sounds in water that are measured relative (re) to 1 μPa and "dB re 20 μPa" for sounds in air that are measured relative (re) to 20 μPa. To make it clear for the reader, this website will use "underwater dB" for underwater sounds. You have experienced the same thing when you talk about the temperature. You should not just say, "It is 50 degrees outside" because that will mean something different to someone living in the United States who uses the Fahrenheit scale and someone living in Europe who uses the Celsius scale. 50 degrees Fahrenheit is equal to 10 degrees Celsius, whereas 50 degrees Celsius is equal to 122 degrees Fahrenheit - quite a difference! To make sure there is no confusion, you should say what temperature scale you are using. It is the same thing with dBs. To avoid confusion, you need to specify the reference level.

a reply to: JIMC5499

Every ten decibels is twice as loud. The F-18 is 146-148 decibels in afterburner, and 143 at military power. So a roughly 90 decibel difference, so roughly 18 times louder, if my limited math skills are right.

originally posted by: JIMC5499

originally posted by: LaBaleine
The sound is extremely loud and distressing; at 235 decibels it is about a thousand times louder than the noise from a jet engine.

A jet engine is about 140 decibels. A thousand times louder? I don't think so.

Sorry, but it is a thousand times louder: A decibel is defined as 10 times the logarithm of the power ratio. home.earthlink.net...

originally posted by: Zaphod58
Every ten decibels is twice as loud. The F-18 is 146-148 decibels in afterburner, and 143 at military power. So a roughly 90 decibel difference, so roughly 18 times louder, if my limited math skills are right.

A 90 db difference is approximately 512 times as loud for sound through air.

+10 db = twice as loud (x2)
+20 db = x4
+30 db = x8
+40 db = x16
+50 db = x32
+60 db = x64
+70 db = x128
+80 db = x256
+90 db = x512.

The sound power and intensity would be approx. 1,000,000,000x higher at +90 db, in air.

a reply to: LaBaleine

No it's not. Every ten decibels is 2x louder.

We are told by psycho-acousticians that a level 10 dB greater usually means "double the loudness" or "twice as loud".

www.sengpielaudio.com...

Even using SPL, it wouldn't be thousands of times higher.

trace.wisc.edu...

a reply to: peck420

See? Crappy math skills when I'm not writing things down and using a calculator, and having someone triple check me. But the point still stands that it's not a thousand times or more.

Thanks.

a reply to: Zaphod58
I don't know how much it matters, too be honest? I am only familiar with how sound propagates through air and solid substrates, in relation to human hearing and human perceptions of "loudness".

This involves sound propagation through water in relation to aquatic senses...to them it could be significantly less "loud" or significantly more "loud" (in comparison to the human ear).

Also, as we are seeing, the power increase is massive, but I don't want to make an assumption that water will behave the same (in relation to the sound propagation and power) at this level. Kind of like aircraft in flight, once you hit the speed of sound, the rules change. Could very well be the case with this as well.

a reply to: peck420

This is a pretty good description of the difference. It's getting into that math thing again though.

www.dosits.org...

originally posted by: Zaphod58
a reply to: peck420

This is a pretty good description of the difference. It's getting into that math thing again though.

www.dosits.org...

Thanks.

Based on that info, that significantly changes the "power" and "loudness". This thing, even at 235 db would create virtually no sound at 1,100 metres (3,600 feet)...a depth whales routinely surpass. And, that is assuming that they used it at sea level. If they are using it under 10m depth (as they are), they are sacrificing a considerable amount of "power" just to overcome the pressure at the depth they are using it at.

I could see this disrupting a whales migratory patterns if it was always outputting, but I don't know of any sonar systems that are continuous. They tend to pulse, do they not?

a reply to: peck420

Generally yes. A torpedo homing on a target is pretty continuous, but from a ship it's generally ping listen, ping listen.

A mapping sonar on an ROV is continuous, but they're fairly close to the bottom.

a reply to: Zaphod58

Depending on the type of sonar there can be a gap between pings lasting anywhere from three seconds to two minutes. Active sonar is rarely used because it tends to give away the location of the vessel doing the pinging. Some torpedoes are designed to have a "home on ping mode". I'd say more but, most of my sonar info is about 30 years old.

a reply to: JIMC5499

Right, and from what I understand if they're mapping they're longer apart because of the distance involved. That's what I was told many years ago anyway.

a reply to: Zaphod58

When I was in the Navy, we couldn't pulse code sonar like they do with radar, so they had to time the pulses far enough apart so that they wouldn't confuse the return echos.

Passive sonar was the way to go.

a reply to: LaBaleine

Would this just be considered standard protocol for them to practice... war like this every few years, or is this part of a very sophisticated and planned preparation for imminent war? Because I remember reading several months ago that Russia was given clearance to do a fly-over of all of Canada to verify its military capabilities etc.

Is North America going to be invaded?