Powerful Sonar Causes Deafness In Dolphins 323
Hugh Pickens writes "Mass strandings of dolphins and whales could be caused because the animals are rendered temporarily deaf by military sonar, experiments have shown. Tests on a captive dolphin have demonstrated that hearing can be lost for up to 40 minutes on exposure to sonar and may explain several strandings of dolphins and whales in the past decade. Most strandings are still thought to be natural events, but the tests strengthen fears that exercises by naval vessels equipped with sonar are responsible for at least some of them. For example, in the Bahamas in March, 2000, 16 Cuvier's beaked whales and Blainville's beaked whales and a spotted dolphin beached during a US navy exercise in which sonar was used intensively for 16 hours (PDF). 'The big question is what causes them to strand,' says Dr. Aran Mooney, of the University of Hawaii. 'What we are looking at are animals whose primary sense is hearing, like ours is seeing. Their ears are the most sensitive organ they have.' In the experiment, scientists fitted a harmless suction cup to the dolphin's head, with a sensor attached that monitored the animal's brainwaves, and when the pings reached 203 decibels and were repeated, the neurological data showed the mammal had become deaf, for its brain no longer responded to sound. 'We definitely showed that there are physiological and some behavioral effects [from repeated, loud sonar], but to extrapolate that into the wild, we don't really know,' said Mooney."
203 decibels? (Score:5, Insightful)
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Can sound get THAT loud? According to this [wikipedia.org], 115dB is the threshold of pain for humans. 203 dB is simply 33,000 times louder.
If you account for the high sound sensitivity of dolphins and water being a better sound conductor, just imagine the damage! It's like dropping a bomb on your head.
Couldn't the sonar be replaced by something less damaging? I guess water muffles radio waves, so a water radar is not a good idea. Maybe a very low frequency radar?
Re:203 decibels? (Score:5, Insightful)
Couldn't the sonar be replaced by something less damaging? I guess water muffles radio waves, so a water radar is not a good idea. Maybe a very low frequency radar?
The problem with that theory is that you'd need such a low frequency that your wavelength would be hundreds to thousands of miles. The antenna requirements alone would make such a system impractical on a mobile basis. Some of the antennas used for ELF submarine communications systems were up to 20 miles long.
Unless you can change the laws of physics I'm afraid we'll be stuck using sonar for the foreseeable feature. If you accept that then you have to accept the fact that the Navy needs to practice with it before they need it in an actual shooting war. Sucks that it apparently harms marine life but what can you do?
Re:203 decibels? (Score:5, Insightful)
Sucks that it apparently harms marine life but what can you do?
Stop human beings from killing each other over nothing, obviating the need for submarines and therefore sonar?
I like to start small and work up.
Re:203 decibels? (Score:5, Insightful)
Stop human beings from killing each other over nothing, obviating the need for submarines and therefore sonar?
Good luck with that.
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Thanks! All I need is a Universal Lobotomiser and some herring.
You know, for the dolphins.
Re:203 decibels? (Score:5, Funny)
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Submarines and sonar is useful for a lot more than just wartime. Check out the wikipedia page for a ton of uses:
http://en.wikipedia.org/wiki/Sonar#Civilian_Applications [wikipedia.org]
http://en.wikipedia.org/wiki/Sonar#Scientific_applications [wikipedia.org]
Re:203 decibels? (Score:5, Funny)
Re:203 decibels? (Score:4, Interesting)
I spent 7 years in the Navy, and we could hear the sonars be tested in port on ships several piers down. The Navy need better listening equipment, not louder speakers. Whales communicate for several hundred miles with whatever their voice boxes can make, and the receiver can hear it and respond. Nature has done it, why can't we?
Re:203 decibels? (Score:5, Interesting)
> Whales communicate for several hundred miles
That's a pretty lowball estimate (src): [sciencedaily.com]
We now have evidence that they are communicating with each other over thousands of miles of ocean. Singing is part of their social system and community.
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Re:203 decibels? (Score:4, Insightful)
If they issued the ping day and night every minute or so, the dolphins would maybe understand to stay away from the dangerous areas.
So would our enemies.
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Or passive sonar. Active sonar (pinging) is like standing in a dark field with a huge omnidirectional beacon. You'll probably see someone else standing around by the light reflected off them, but they'll certainly see you first.
Passive sonar is like hiding in a dark corner of the field watching everyone else stumbling around with flashlights. Their lights may not be very bright (i.e., the ships' engines and hulls may be very quiet), but they always make some noise, which your super-sensitive passive sona
Re:203 decibels? (Score:5, Informative)
The thing of it is, submarines don't use, and don't need a super-powerful active sonar.
This is for surface vessels ("targets" in bubblehead vernacular) searching for subs, not subs hunting each other.
These hyper powerful sonar systems are for surface vessels to locate submarines that may be in the vicinity. When you get into costal areas, the noise of the surf, the temperature gradients (from the shallow bottoms) and the salinity gradients from the fresh water from the rivers, plays havoc with normal sound transmission.
This massive system is used to plow through all that, and still return a signal clear enough to spotlight the sub lurking around the area.
(former US Navy submarine Sonar Tech)
Re:203 decibels? (Score:4, Informative)
Passive sonar, decent stuff at least, is ALWAYS a towed array. Gets the hydrophones away from the ships hull, reducing self noise. That said, I'm not sure exactly which types of vessels carry a towed passive array... destroyers, cruisers, frigates, but i think that's about it. Plus the helo-dropped sonar bouys.
As for as potential enemy capabilities compared to ours, I'm not at liberty to comment one way or the other
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But considering how sensitive active sonar is, how strong does a ping need to be in order for its reflection to be received by the passive component of the targeting system?
Re:203 decibels? (Score:5, Informative)
Active sonar really doensn't give anything away since once you launch a torpedo, the target, or anyone else in the area, is going to know where the sub is anyway.
What are you basing that assumption on? Modern torpedoes can be programmed to run a lower (i.e: harder to detect) speed until they get close to the target and/or further away from the launch platform. The loudest part of a torpedo launch is the "launch transient", i.e: the sound of the compressed air that pushes it out of the torpedo tube. Some submarines (the Seawolf class) use larger torpedo tubes that allow the torpedo to "swim" out without requiring a blast of compressed air, thus negating most of the noise of a torpedo launch.
Assuming that you are going to detect the launch is a very dangerous assumption in modern naval warfare. Your first indication of incoming "fish" is just as likely to be when they turn on their active seekers at close range and go to full speed. In that scenario you are virtually SOL and don't even have the means to retaliate.
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>Couldn't the sonar be replaced by something less damaging? I guess water muffles radio waves, so a water radar is not a good idea. Maybe a very low frequency radar?
I say we replace the submarines with dolphins. We can make them effective by attaching laser beams to them. This has the added bonus of allowing us to stop worrying about the dolphins until some genius decides to mount laser beams on sharks. But no one here would ever dream of doing such a thing, so we'll be good to go!
Re:203 decibels? (Score:4, Informative)
Wrong. 20dB is 10x the power.
Measuring from 0dB? Are you sure? [k12.il.us]
From the link a few of us are too lazy to click:
The threshold of hearing is assigned a sound level of 0 decibels (abbreviated 0 dB); this sound corresponds to an intensity of 1*10-12 W/m2. A sound which is 10 times more intense ( 1*10-11 W/m2) is assigned a sound level of 10 dB. A sound which is 10*10 or 100 times more intense ( 1*10-10 W/m2) is assigned a sound level of 20 db. A sound which is 10*10*10 or 1000 times more intense ( 1*10-9 W/m2) is assigned a sound level of 30 db.
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That sucks for them (Score:5, Funny)
Guess dolphins and whales can't go to concerts. Although, I hear The Pingers have quite the underwater following.
In other news, when exposed to brilliant flashes of light, humans are rendered temporarily blind.
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Experiments like these... (Score:5, Insightful)
Experiments like these are like putting people next to a jet engine to see if their hearing gets damaged. I am no PETA freak, but putting 200+ decibels is bound to do permanent damage. I know they said it is temporary, but that might be like my "temporary" hearing loss from the Boston show a few months back. Yes, I could hear fine afterward* but I wonder what incremental loss I might have had from all that loudness.
*I have higher pitch loss that apparently came from shooting a lot many years ago without hearing protection.
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Anything that is used for prolonged periods (16 hours) is going to have detrimental effects on the mammals' methods of navigation. Why is it such a terrible crime that the Navy consider what damage it does to its surroundings? Not implying you, it's just their stance is
Re:Experiments like these... (Score:4, Insightful)
Why is it such a terrible crime that the Navy consider what damage it does to its surroundings?
What makes you think they don't already or that the damage to those surroundings is more important than our ability to keep the sea lanes open in the next shooting war?
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I ask because there are huge numbers of places where human lives could be saved with trivial effort and at trivial expense; but very, very few people actually follow through on many, or even any, of them.
For instance, consider the thousands of children a year that die of trivial gastrointestinal complaints every year. Most of them could be saved by a course or two of oral rehydrati
saving humans (Score:3, Interesting)
I'd personally kill every Dolphin myself if it would save a human life.
Ah, if you kill every dolphin, you'll also be killing humans. Though rare, dolphins [msn.com] have saved humans, especially from sharks [all-creatures.org].
Falcon
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OP was examining the long term effects of this experiment on the dolphins being experimented on and not the short term effects of SONAR use in the wild.
Re:Experiments like these... (Score:4, Insightful)
Because the design purpose of a Navy is to kill people and break things?
Or are you really suggesting that they should spend more time finding ecologically friendly ways to sink ships and kill people?
Re:Experiments like these... (Score:4, Insightful)
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I am no PETA freak, but putting 200+ decibels is bound to do permanent damage.
Perhaps the experiment was inhumane. Hypocrisy demonstrated. Point taken.
That does not change the conclusion: military exercises that include sonar cause injury to advanced marine life.
The ramifications should be obvious, but just in case they aren't...
Harming endangered species is illegal, and for good reason...their extinction could have unwanted ecological consequences and will certainly have unwanted sociological consequence
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nobody wants a PETA riot
Sure I do! That way DHS swoops in, rounds them up, and (based on all the left-wing whining and ravings you see in places like /. and dailykos) throws them in Gitmo with thousands, nay, billions of other domestic political prisoners and Belgians.
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You gotta catch up with the wingnuttery, dude. These days it's all right-wing whining about FEMA internment camps for Patriots, terror that the gubmint will take away their AK-47s, and the xenophobic "DEY TOOK OUR JAHBS!" ranting about immigrants.
The left sounds positively sane by comparison.
No, 9/11 truthers make everyone look sane by comaparison, and a new assault weapons ban would make obtaining AK-47s difficult, thus not an unrealistic concern. And the crowd yelling, "DEY TOOK OUR JAHBS and sent them o
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The building of Navy vessels most certainly has greater unintended/unwanted consequences than occasional deafening of advanced marine life. But either of those compared to a lack of preparedness on the part of our military to defend against threats foreign and domestic...Well, I guess it is all a matter of perspective.
Re:Experiments like these... (Score:5, Insightful)
I am no PETA freak, but putting 200+ decibels is bound to do permanent damage.
The document linked on the Bahamas stranding says that source levels were 223 - 235 dB and levels were less than 180 dB at 300 m horizontally and 200 m vertically, so unless the dolphins were EXTREMELY close to the ships when the sonar was turned on the odds of even temporary deafness due to the use of sonar in the wild are quite low. Remember: a 40 dB difference in signal is a factor of 10,000 in amplitude of the pressure wave, so unless the dolphins were within a few meters of the source they would be very unlikely to get anything close to 200 dB.
This is a bit like dropping a 10 kg mass on a person and noticing it causes serious damage, and then arguing that you can say something about the effects of dropping 0.001 kg masses on people based on the 10 kg data.
That's not to say that it isn't plausible that dolphin sonar can be screwed up by powerful sonar, but this experiment just doesn't seem relevant to the question.
Re:Experiments like these... (Score:5, Insightful)
180 db is still extremely strong. Now, compound that with the fact that the Submarines are moving, pinging and that Dolphins are curious anmials and like to follow ships... and I think you will find that the chances for Dolphins being near one of these ships greatly increased.
Also, I understand the need to defend the human race, military and blowing stuff up, but ask any blind person how much noise pollution hurts and then comment again.
Re:Experiments like these... (Score:5, Insightful)
I think you're both essentially right.
If the dolphins were further away, the sonar would be far less damaging, but it could still interefere with their navigation.
It's also very possible that the dolphins were following the ships and exposed to deafening decibel ranges.
This study (like most studies) is just a stepping stone to narrow down criteria/goals for other studies...we need to A) Determine the effect of lesser decibel levels and B) Gather real observational data on how often dolphins and other marine life venture very near to naval vessels.
Ultimately results of these studies should just regulate situations on when active sonar is used, where you can train with it, etc, because active sonar is necessary until something better is developed. Despite the very slim chances of nuclear war, as tragic as it is, I'm willing to sacrifice a few hundred sea critters (I wold hope it's a much smaller number though) just to know that we can effectively track and destroy nuclear missile subs (as well as the many other uses for sonar). That's just my opinion and you can call me a barbarian for it if you like.
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I'd like someone to explain why active sonar is necessary, being that subs are most effective when their location is not known, and active sonar instantly gives away your location.
Err, active sonar isn't just the domain of submarines. Subs very rarely use it, but sub-hunting aircraft like the SH-60, P-3, Il-18, etc. use combinations of active and passive sonobuoys, as well as dipping sonars (for the helicopters) which have active and passive modes. Surface ships like destroyers will also use active sonar on occasion. Many modern submarines are quiet enough that they can't be heard at all on a passive set, particularly when operating in littoral areas or areas of mixed or disturbed
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A couple of things: submarines don't use active sonar if they can possibly help it - active sonar is very helpful in locating someone, but it's even more helpful in announcing your presence to everyone out to well beyond the range the
Re:Experiments like these... (Score:5, Informative)
Unfortunately, neither you nor I can assess what "203 decibels" means. That is because that is a meaningless phrase. Here is the information that the AFP left out:
The difference between the reference range measurement and the receiver measurement, assuming spherical spreading (which we're likely to see at a 40m range), is 20 log r, where R is the ratio of the reference range and the receiver range. If the dolphin is 100 m away from a source emitting 203 dB at a 1 yard reference range, it will be hit with acoustic energy at 163 dB (203 - 20 log 100).
By the way, the sound pressure levels you're accustomed to reading about as an land-lubber are probably dB//20 uPa -- i.e., measured in multiples of 20 micropascals. In underwater acoustics we almost always use dB//1 uPa -- i.e., measured in multiples of 1 micropascal. To convert from the in-air numbers to under-water numbers, add 26 dB. A 203 dB sound to an underwater physicist would be a 179 dB to an atmospheric physicist.
Unfortunately I cannot find this article on the Biology Letters [royalsocie...ishing.org] web site to check the facts.
Re:Experiments like these... (Score:4, Insightful)
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Sort of like dropping a nuke on Denver in order to kill a few deer? Is it okay if I promise to eat everything I kill?
Well, if you go deer hunting with nukes you don't have to worry about cooking the meat afterwards ;)
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Well if you're really so pressed for time... [lmgtfy.com]
According to the very first result, a sonar source of 240dB will result in a perceived intensity of 180dB at a distance of 1km, and 150-160dB at a distance of 160km. However, this does not mean that the experiment was "dumb", and your attempt to dismiss what was in fact an entirely rigorous scientific experiment solely on the basis of your own failure to read the damned summary (let alone TFA) is more than a little grating.
In actual fact, prior research (albeit
F Dolphins (Score:3, Funny)
you dont' need to make dolphins deaf. (Score:4, Insightful)
You don't need to actually make dolphins deaf to know if they will be deaf! Not only is that cruel, it's unnecessary.
It's common knowledge that exposure to 200+ decibels will make anything deaf. And this Dr. Mooney is an idiot.
If it makes them deaf in a lab, it fucking works outside the lab!
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It's common knowledge but now he's done a STUDY ("Oooooooh, Aaaaaaaah"). That means that what everybody already knew has somehow become more official!
I think this is a new plan.
1. Find some obvious thing that everyone already knows.
2. Get funding to have a "study" on it.
3. ???
4. Profit!
Re:you dont' need to make dolphins deaf. (Score:4, Insightful)
This study represents a "nail in the coffin" type of study, where it is now known unequivocally that 203 decibels will harm wildlife. To logical people, this is what's known as "proof". Knowing this, you can now measure the sound level of the Navy's sonar tests and if it's above 203 decibels, you have direct evidence that the Navy IS harming marine animals. It sounds silly and trivial, but this is how logic works sometimes, you have to prove something beyond a shadow of a doubt, and past a shadow if you want to change society.
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> it's unnecessary.
I'd say ears are unnecessary to navies to about the same extent that eyes are unnecessary for armies.
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Have you ever seen a Dolphin? They aren't boats. The ability to keep their ears above water for an extended period of time would consume a lot of energy if they could even do it. Also, why is it that the dolphins have to change their million years of instincts and evolution so that we can search and destroy enemy ships. On that note, when was the last time we actually had to destroy a submarine?
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You don't only care about the u-boats you want to destroy. You also care about the ones that pop up into the middle of a carrier group to say "Hi! Naval superiority? Yeah, you're OUR bitch now." [dailymail.co.uk] China has the superiority. It'd be real nice if we could take it back, seeing as how likely a shooting war on that side of the world is.
Re:you dont' need to make dolphins deaf. (Score:5, Funny)
It's common knowledge that exposure to 200+ decibels will make anything deaf.
Apart from deaf people.
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This probably causes permanent damage. (Score:5, Interesting)
Loud noises tear the cilia in your cochlea out by the roots. In humans, and, as far as I know, other higher mammals, they don't grow back (Can someone who knows confirm that this is true in dolphins as well?).
So the word "temporary" might make this sound less bad than it is: Our sonar may only temporarily cause total deafness, but I suspect it permanently degrades hearing.
Sucks to be a dolphin. Reminds me of Douglas Adams' sympathy for whales, whose songs no longer can be heard across the ocean. (I think Douglas talked about this in Last Chance to See.)
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Even if it is temporary, isn't this the equivalent of temporary blindness while on the highway?
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These methods are definitely cruel. On the other hand, if the research actually led to a reduction in the power of sonar systems used, then it would be worth harming a few dolphins. The problem is that if anything the research will be used to figure out the minimum sonar power required to paralyse dolphins for capture so they can be trained as mine sweepers or something.
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Plus if whale song isn't happening for a while, a space probe will come by and wreck everything.
please don't tap on the glass (Score:2)
Maybe they beached just to get away from the awful noise?
Temporary damage and singing under water... (Score:4, Informative)
It's the "Brown Note" for dolphins and whales . . (Score:2)
. . . I don't think it's the decibels, but the frequency. Obviously military sonar frequency is the "Brown Note" http://en.wikipedia.org/wiki/Brown_note [wikipedia.org] for dolphins and whales.
The sound is not just making them deaf, it's scaring the poor critters shit-less.
to the "wellduh" taggers (Score:5, Insightful)
My wife is a wildlife conservation researcher, and specifically works with animals in the Delphinidae family (which include dolphins). There's a lot of stuff she, and others, have to - must - verify, even if it seems to be a "wellduh."
The alternative would be that science just thinks correlation = causation. Is that what we want? "Well, Navy ships used sonar, and these whales stranded themselves...must be related. Case closed." Instead, someone did actual science showing that sonar causes real deafness in these animals. And someone wants to harsh that?
I say instead that there should be a tag, "abouttimetheyverified"
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Science is only useful to some people when it aligns with their sensibilities. That goes for pretty much all sides of whatever debate you are in.
In this case, the point is that they would rather not risk any dolphin be hurt to get a scientific answer. That's actually a fair position, as it is the one we take with humans.
That said, the Navy isn't just testing SONAR for shits and giggles, and you can be certain that the Chinese and Russians don't give a shit about dolphins. That means that it's necessary f
Dolphin stranding in ancient Greece (Score:4, Insightful)
Classic Greek authors tell us that in the ancient Greece, dolphins and whales were already found stranded on the shore. This was a windfall for the locals, who were not eating meat very often. They saw it as a divine gift and thanked Poseidon for it.
So considering that the Greek galleys didn't use sonar, we need to stop barking at the wrong tree and find the cause of this phenomenon. My money is on a parasitic disease that affects the brain [caltech.edu].
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Classic Greek authors tell us that in the ancient Greece, dolphins and whales were already found stranded on the shore. This was a windfall for the locals, who were not eating meat very often. They saw it as a divine gift and thanked Poseidon for it. So considering that the Greek galleys didn't use sonar, we need to stop barking at the wrong tree and find the cause of this phenomenon.
Unless, of course, there was a sonar-equipped sub from Atlantis somewhere nearby... Or submerged alien vessels.
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Yeah, well, that's the kind of assumptions you need to make if you want to keep blaming the sonar of the *EVIL MILITARY* (thunder rolls).
The arrogance of every young generations is to believe all problems on Earth are created by their parents' incompetence. Get a haircut and a bath, you hippies!
Re:Dolphin stranding in ancient Greece (Score:5, Insightful)
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Remember: this is /.
So please stop making complete and utter sense.
But continue blaming Windows.
And it's bark "UP" the wrong tree, not "AT", OP.
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From the summary:
Most strandings are still thought to be natural events, but the tests strengthen fears that exercises by naval vessels equipped with sonar are responsible for at least some of them.
No one said that strandings aren't a natural phenomenon. They have multiple causes! You didn't even have to click a link to see that!
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So considering that the Greek galleys didn't use sonar
[Citation needed]
Excellent (Score:2, Interesting)
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Not all decibels are the same! (Score:5, Informative)
WRT to all of the "203 decibels, OMG!" comments: water decibels aren't the same as SPL decibels.
A decibel is the logarithmic relationship between one quantity and a reference quantity. For sound pressure level, we use the RMS pressure of the sound wave compared to a reference pressure that represents the threshold of human hearing (20 microPa): 20*Log10(P/20e-6)
Other types of decibels use different reference quantities. For example, vibration velocity in the USA uses a reference quantify of 10^-6 in/sec. Sound intensity (sound power through a unit area) uses a reference quantity of 10^-12 W/m2. So comparing sad sound intensity decibels to vibration velocity decibels is meaningless without normalizing the units.
In the case of water decibels, we use pressure as we do for SPL in air, but the reference quantity is different: for water, the reference quantity is typically 1 microPa. Therefore the 203 dB in water is approximately equivalent to about 170 dB SPL in air. Of course you still can't directly compare water dB to SPL because the wavelengths of sound in water are so much longer than wavelengths of sound in air.
In any event, 203 dB in water is very loud (and obviously harmful to aquatic life as demonstrated in the articles), but not necessarily in the same way that 173 dB SPL is loud/harmful to us.
Good thing (Score:2)
It's a good thing this affects dolphins instead of sharks. What platform would we use for our lasers if sharks were this easy to mess up?
Good... (Score:2)
...now when they come for us, we'll be ready.
Wrong solution (Score:2)
It seems that the Navy may be pursuing the wrong solution to increasing sonar range and resolution. Rather than increasing the transmit power to such levels, perhaps more sensitive receivers are needed. Whales and dolphins echo location capabilities exceed the current capabilities of Navy equipment and they don't need any 200db or more power outputs.
It is believed that whales can communicate over hundreds of miles. Such levels of sensitivity also lend themselves to passive detection (for the Navy) which is
A small problem with the conclusion (Score:3, Interesting)
To the best of my knowledge, SONAR is short bursts of loud noise broken by longer periods of quiet to receive and process the return echos. Two minutes of continuous sound is not going to happen. Even if the effect is cumulative, a cetacean would have to travel with the source for over five minutes which it is unlikely to do if the SONAR is injurious. Would you hang out in an excruciatingly loud environment?
Now, some will point to this:Sound can become trapped if a layer of warm water lies over cold water. When sound created in the warm zone reaches the cold water it can bounce back instead of travelling though it. This, Dr Mooney said, would have the effect of trapping the sound in the warm layer, where it would bounce around "like a ping-pong ball", giving whales and dolphins little chance of escaping it.
But, the thing is, dolphins and whales are mammals. The would leave the noisy layer when they surfaced. Therefore, they would quickly learn how to escape the sound: surface or dive.
The conclusions seem specious to me.
Re:Retarded (Score:4, Insightful)
The reality is that they don't particularly care. They have to, for purposes of public relations, act like there's no problem, like what they're doing is perfectly fine, but the reality is that they could care less if every cetacean in the ocean died tomorrow.
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No it isn't.
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Must be nice to be in a permanent state of denial.
It sure is! ...assuming that if someone tries to call you on it you happen to have a powerful army at your disposal...
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Or maybe all craft have both active and passive capability, but the civvy crafts are less likely to need active for anything, and certainly military craft are more likely to test their active sonar more often.
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Civilian craft rarely have passive sonar.
Civilian active sonar tend to be very low power.
Civilian craft tend to rely on radar for finding stuff they want to not run into. Microwaves are strongly absorbed by water. Therefore, marine life is strongly shielded from such emissions by water. For this reason, civilian ships detection systems pose minimal threat to sea life. (Their engine noise, however...)
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not a lot of high powered sonar use in the civilian world, i would guess.
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what do you think?
the military probably uses less sonar in day to day operations than the rest of the scientific community does.
after all, how can you plot out that wreck without side scanning sonar?
how can you map those undersea ridges and trenches without using some sort of down firing sonar?
the truth of the matter is, sonar as used by the military is mostly a passive system.
it's kinda like sitting out in the woods while hunting. you don't go around making a lot of noise because it can be heard further aw
Contradicition: (Score:3, Insightful)
http://www.underwatertimes.com/news.php?article_id=48723961015
That study used fish. Fish are not mammals but dolphins, porpoises, and whales are.
Not that I personally believe it don't effect them, though we may not know how to tell.
Marine mammals [oceanmammalinst.com] are shown to hemorrhage from sonar.
Falcon
Re:Disarmament (Score:5, Interesting)
you do realize that 99%+ of the time, these terrible nuclear submarines don't even use ANY form of sonar other than underwater microphones don't you?
To a similar (though not as high degree) neither do surface ships.
I didnt think so.
yet another example of a slashtard talking out of their ass with absolutely NO idea what they are talking about.
And yes, I did happen to serve on one of these terrible nuclear submarines.
and in the case of missle subs, it's probably closer to three nines or more.
ssbn subs are holes in the water that strive to make absolutely no noise.
you can hear the original sound wave a lot further off than you can hear the return echo which is always weaker.
and that's before you even throw in the effect of temperature gradients and convergence zones.
another thing to ponder is what was the frequency used?
and does this matter.
the reason i say this is that MOST sonar is low frequency or extremely low frequency, with the exception being high frequency sonar used to search for underwater mines and to penetrate ice fields.
of course, why mention these type things as they will just muddy the waters and potentially invalidate the test.........
(I said potentially, not that they do, i have no idea and based on the report, neither does anyone else)
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people use sonar trying to FIND subs, moron. If the subs aren't there, no sonar.
God, no wonder you went into the military. no other options.
You are the moron. Subs dont use active sonar unless there is no other choice because it reveals their location. Subs use passive sonar 98% of the time. Calling him a moron and having no choice is an assumption based on that you are the moron. Any member on a submarine is not your normal enlisted seaman, they actually have to screen candidates so they can get the job done. Its not some infantry man throwing on some headphones and listening. Also if submarines used active sonar, we would never have news ab
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You do know that subs very rarely use active sonar? It is giving away your position. Surface ships tend to use active sonar to assit in finding subs that are trying to hide. First strike weapons hide. That is their first goal. If you use active sonar you tell everyone within a couple hundred miles of exactly whereyour hiding.
Then again your an AC you probably don't know such basic things.
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Oh, yeah, slashdot is a conservative hotspot!
Brett
Re:We can't stop or the terrorists will win! (Score:4, Interesting)
Our Military superiority, (or inferiority,) dictates how much economic pressure we can apply.