In article <dalton-0D4023.23533124022...@news.eternal-september.org>,
David Dalton <dal...@nfld.com> wrote:
> What are some strategies for reducing ship, sonar, and
> seismic airgun array noise in the oceans in order to
> reduce negative effects on marine mammals?
I also posted that to sci.engr and other groups and
there have been a couple of interesting replies
there already.
In article <dalton-73F291.02580625022...@news.eternal-september.org>,
David Dalton <dal...@nfld.com> wrote:
> In article <dalton-0D4023.23533124022...@news.eternal-september.org>,
> David Dalton <dal...@nfld.com> wrote:
> > What are some strategies for reducing ship, sonar, and
> > seismic airgun array noise in the oceans in order to
> > reduce negative effects on marine mammals?
> I also posted that to sci.engr and other groups and
> there have been a couple of interesting replies
> there already.
I also just posted to sci.military.naval and other groups.
>In article <dalton-0D4023.23533124022...@news.eternal-september.org>,
> David Dalton <dal...@nfld.com> wrote:
>> What are some strategies for reducing ship, sonar, and
>> seismic airgun array noise in the oceans in order to
>> reduce negative effects on marine mammals?
>I also posted that to sci.engr and other groups and
>there have been a couple of interesting replies
>there already.
You know multiposting is kind of rude. It breaks a discussion up. It's
clear you have already crossposted, why not just crosspost to all relevant
groups and drop some of the irrelevant ones?
The thing is, while you can reduce the noise from ships by playing with
hull profiles to improve laminar flow and reduce turbulence, and playing
with prop designs to reduce turbulence and cavitation, there is nothing
you can do about sonar noise.
Because... the whole point of sonar is that it's a loud noise.
What you _can_ do is to move the operating frequency of the sonar to
notes that don't bother mammals, and to do that you need to first find
out what really does bother them. Which nobody really is completely
sure about, it seems.
--scott
-- "C'est un Nagra. C'est suisse, et tres, tres precis."
On 2012-02-25 klu...@panix.com(ScottDorsey) said:
>It's clear you have already crossposted, why not just crosspost to
>all relevant groups and drop some of the irrelevant ones?
i would agree with that. These cross posted threads usually
turn into noise themselves though <g>.
I'm wondering what his interest is, whether he's just dabbling or he has an
academic interest of some sort. IF the later I'd think he'd
have already cracked a book or two on the subject.
>The thing is, while you can reduce the noise from ships by playing
>with hull profiles to improve laminar flow and reduce turbulence,
>and playing with prop designs to reduce turbulence and cavitation,
>there is nothing you can do about sonar noise.
>Because... the whole point of sonar is that it's a loud noise.
>What you _can_ do is to move the operating frequency of the sonar to
>notes that don't bother mammals, and to do that you need to first
>find out what really does bother them. Which nobody really is
>completely sure about, it seems.
Would agree, and though we might have a bit of knowledge I"d
think that for the most part rec.audio.pro is not the
appropriate group to which to address such queries. But,
in addition to Scott's discussion of sonar and animals the
other question would be if sonar pings at the frequencies
that don't harm the animals are effective at doing the job
sonar is supposed to do. I'm no expert in underwater
acoustics though, and doubt there are few in this newsgroup
<grin>. Some of the film sound guys who do underwater
shoots might be able to address it a little more
intelligently than a bunch of live sound and studio rats,
but still, i'd say the oceanographers and others might know
a bit more on the subject. Here in this group most of us
have a better grasp of acoustic characteristics of air
<grin>
Richard webb,
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it's too damn bad!
send your spam to:
postmas...@rediffmail.com or
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In article <jiam9c$m3...@panix2.panix.com>,
klu...@panix.com (Scott Dorsey) wrote:
> David Dalton <dal...@nfld.com> wrote:
> >In article <dalton-0D4023.23533124022...@news.eternal-september.org>,
> > David Dalton <dal...@nfld.com> wrote:
> >> What are some strategies for reducing ship, sonar, and
> >> seismic airgun array noise in the oceans in order to
> >> reduce negative effects on marine mammals?
> >I also posted that to sci.engr and other groups and
> >there have been a couple of interesting replies
> >there already.
> You know multiposting is kind of rude. It breaks a discussion up. It's
> clear you have already crossposted, why not just crosspost to all relevant
> groups and drop some of the irrelevant ones?
It is recommended not to crosspost to more than five groups
but yes I agree I could have dropped some, but the other
two crossposts were afterthoughts after this one.
<0junk...@nomail.bellsloth.net> wrote:
>I'm wondering what his interest is, whether he's just dabbling or he has an
>academic interest of some sort. IF the later I'd think he'd
>have already cracked a book or two on the subject.
There is an outrageous amount of information on the subject in open
publications from the US Navy. A lot of it has to do with very fancy
propeller designs. Expensive propeller designs, mind you, which is
why you don't see them on merchant marine vessels.
The Navy wants to build ships that aren't audible on passive sonar receivers. Incidentally, some of the problem with building very quiet
ships is that animals run into them.
> Some of the film sound guys who do underwater
>shoots might be able to address it a little more
>intelligently than a bunch of live sound and studio rats,
>but still, i'd say the oceanographers and others might know
>a bit more on the subject. Here in this group most of us
>have a better grasp of acoustic characteristics of air
It's amazing how the physics are the same. The reason I got interested in
it is because almost all of the research on large phased array microphone
systems is Navy-financed stuff. Beamforming in air is really interesting and
a lot of the ocean work can be applied to it.
--scott
-- "C'est un Nagra. C'est suisse, et tres, tres precis."
klu...@panix.com (Scott Dorsey) writes:
> [...]
> It's amazing how the physics are the same. The reason I got interested in
> it is because almost all of the research on large phased array microphone
> systems is Navy-financed stuff. Beamforming in air is really interesting and
> a lot of the ocean work can be applied to it.
What beamforming/phased array application are you interested in, Scott?
-- Randy Yates
DSP/Firmware Engineer
919-577-9882 (H)
919-720-2916 (C)
