Exposure to military sonar may cause temporary hearing loss in bottlenose dolphins, scientists at the Hawaii Institute of Marine Biology have found. Tests on a captive dolphin indicate exposure to sonar at high, prolonged levels can cause temporary deafness for as long as 20 to 40 minutes — but only if the dolphin stays close to …
how green was my valley?
For all the talk of "green" issues in the media and corporate or governmental PR releases, how many people actually give a shit about preserving ecosystems and flora and (mega-)fauna? Sadly most people who will gladly parrot "carbon reduction" mantras will have little visibility or understanding of how we are wrecking the natural environment in much more direct ways via pollution (noise, light, air, water), over-exploitation (cod, anyone?) or simply by externalising the damage via either a socio-economic (let developing countries pay the cost) or a temporal (let our great grandchildren pay the cost) mechanism?
Subject unrelated, unless it somehow links in with beached W(h)ales?
No sh1t Sherlock
"Tests on a captive dolphin indicate exposure to sonar at high, prolonged levels can cause temporary deafness for as long as 20 to 40 minutes — but only if the dolphin stays close to the source of the sonar for several minutes."
Talk about your bloody obvious. Of course the poor dolphin went deaf! So would anything with ears listening to noise at those sort of levels. What are they going to try next? Shine 10,000 watt lights into dogs eyes and see if they go blind? Fecking idiots.
"Other sensors showed the dolphin's breathing rose significantly when the sonar was switched on."
My breathing rises significantly as I try to stop myself from destroying the stereo owned by the tw@t who lives above me and doesn't understand/care that his sub uses the floor as an amplifier. It's called STRESS. I'm no tree hugging, lentil eating hippy (I like nothing better than minced cow between two bits of bread) but this type of pointless cruelty really bugs me.
Stupid so-called scientists like these should be used for 'scientific' studies instead of <insert test creature>. Let's see how their hearing fairs when subjected to prolonged loud noise.
Think of the Dolphins!
I for one am wholly unimpressed with the idea of taking what is known as an extremely intelligent mammal, penning it and then blasting it with excessive sound levels in order to render it, even temporarily, deaf.
Would the scientists concerned please consider nailing their legs, through the kneecaps, to planks of wood in order to determine how long they remain lame afterwards.
let me guess..
that military sonar 'experiments' have nothing to do with the scores of dolphins and whales beaching themselves recently.. pure coincidence. pah!
the 'Decibel Pedants'!
No dolphins were harmed in the writing of this comment (although some possibly were in the production of today's tuna sarnies for lunch)!
Loud as Hell
"like a gun shot 1 meter away — but that's still loud as hell"
I've been unlucky enough to experience a shotgun discharge at a distance of half a metre from the barrel. (Obviously pointed in another direction, otherwise I wouldn't be typing this)
I would like to point out that 'loud' doesn't even begin to describe it - the shockwave causes temporary overload of ALL senses, experienced as a temporary blinding/deafening whiteness.
I do think its unfair to use humans experience of loud noise as an illustration of how dolphins are likely to do so, since their sense of 'hearing' is many times more sensitive than ours.
Ok.... A little more.
Two things you say are things that realy get to me.
1) Companys and people saying how "green" they are, yet happily eating cod, not because of cost, but because they think its fine.
2) Passing on the costs and damage, not to great great grand children, but to there children. So many of the people you see campaining about green issues are people with time and money, who made this in the 70s and 80s. They expect there children to pay the costs, the ones with little time and money. The one example that most anoyes me is recycling. It is all build on the assumption that you have room for three bins, both in your garden and your kitchin, and that noone lives in a flat, yet we are forced to live in a small flat BECAUSE the same people who bang on about this are the ones with nice country homes who don't want any building near them, so we are stuck in a flat that costs more than my parants genaration paid for there house (alowing for inflation of course)
Loud as Hell
I woud have thought that Hell would be louder than that, what with all the Weeping and Gnashing
of Teeth of the millions of souls that are resident, or does the writer know something that we don't
(I'll get my coat, the one with the Dog collar in it)
'A deaf whale is a dead whale'
I feel marine biologists distressing this one dolphin is ethical because active sonar is so ubiquitious now, dolphins and whales are dying from this. The data from a dolphin in a swimming pool played repeated pings doesn't easily fit into newspaper science columns though as it doesn't readily translate to damage in the real world. For instance, hearing rifle fire or a siren approaching from a distance is a lot less damaging than someone sneaking up behind you and emitting the same noise blast.
I believe some beachings are caused by loud noise from natural sources, and from other man-made noise such as underwater explosions, but that naval sonar is a large and increasing contributory factor. Mass strandings can be caused by active sonar even if it isn't deafening, in a similar way to bison being stampeded off a cliff. I refuse to believe in this day and age that the only way to 'see' underwater is to blast the entire environment with noise.
Where is the feckkin' "NO SHIT?" button?
"...scientists have reported the first controlled study on the effects of sonar in dolphins." ??? Hardly
"Temporary auditory threshold shift" or temporary hearing loss as a function of loud sonar sounds has been studied in dolphins and related species for over 15 years by the Navy and in other laboratories. This appears to be the first study wherein the measurements of that temporary loss was inferred by measurements of neural activity rather than by behavioral indicators that were used in the other studies. However, it's finding, regarding underwater sound level and duration of loss, are in line with those previous studies - but not original in that regard.
Further, the author's conversion of 203 dB in water to 170 dB in air is also in error and highly misleading. The conversion must take into account both the difference in reference level (20 microPascal for air v. 1 Micropascal for water) as well as differences in the acoustic impedance (rho x c) between air and water. The two together produce a difference of about 62.5 dB and not the 33 dB difference stated by the author. Previous research showed that, with that equivalence, susceptibility to temporary hearing loss and its duration, as a function of received energy, were in line with those observed in typical terrestrial mammals.