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[Nature Recordists] Digest Number 6463

To: "" <>
Subject: [Nature Recordists] Digest Number 6463
From: "" <>
Date: Wed, 2 Sep 2015 08:13:49 +0000
There are 8 messages in this issue.

Topics in this digest:

1a. Re: underwater stereo recordings and phase    
    From:  madl74
1b. Re: underwater stereo recordings and phase    
    From: Jim Wells
1c. Re: underwater stereo recordings and phase    
    From: Dan Dugan
1d. Re: underwater stereo recordings and phase    
    From:  madl74
1e. Re: underwater stereo recordings and phase    
    From:  madl74

2a. New study shows traffic noise is disruptive to wildlife    
    From: J. Charles Holt
2b. Re: New study shows traffic noise is disruptive to wildlife    
    From:   
2c. Re: New study shows traffic noise is disruptive to wildlife    
    From: Bernie Krause


Messages
________________________________________________________________________
1a. Re: underwater stereo recordings and phase
    Posted by:   madl74
    Date: Tue Sep 1, 2015 5:26 am ((PDT))

> I still don't see why whether the reflected wave, either from the surface > 
> or from a solid reflector, should have any more effect than the same in 
> an air environment. 

Russell, 

A reflection takes place at a boundary where the speed of sound (or light) 
changes. For a reflection from slow to fast, most of the energy is bounced 
back in phase. from fast to slow, the surface can't return the energy which 
is reflected back in antiphase as energy has to be conserved. 

See:
http://hyperphysics.phy-astr.gsu.edu/hbase/sound/reflec.html 

An illustration of this effect is with organ pipes which are either closed 
or open.  A closed (stopped) pipe produces a sound one octave lower than an 
open pipe. 

David Brinicombe 






Messages in this topic (12)
________________________________________________________________________
1b. Re: underwater stereo recordings and phase
    Posted by: "Jim Wells"  whitby333
    Date: Tue Sep 1, 2015 8:57 am ((PDT))

Hey all,

Everything David is saying is impeccably correct.  Pretty sure:).

I 'think' what Russell is asking is what practical difference does it make.  Or 
maybe he's asking what the difference is between air and water.

To the latter I'd say while similar (both are sound), sound acts differently in 
different media.  

But to the former, the more you know about the physics of the medium you're 
recording:
a.  The more you understand about what you're hearing
b.  The better you might choose mics, and placement... for example.

Theory is dry, and science, and all, but when you get into it it's also filled 
with beauty.  Recording (anywhere!) is both art and science... when done well:).

I guess 'the difference' is in the ear of the beholder:).

For the record, I'm new here.  While I've never had the opportunity to record 
under water, it's fascinating to read the parallels between air and water, and 
I enjoy the level of technical expertise I've seen so far.
Best,
Jim, CA

Have fun!
www.fantasonics.com

> On Sep 1, 2015, at 5:26 AM,  [naturerecordists] 
> <> wrote:
> 
> > I still don't see why whether the reflected wave, either from the surface > 
> > or from a solid reflector, should have any more effect than the same in 
> > an air environment. 
> 
> Russell, 
> 
> A reflection takes place at a boundary where the speed of sound (or light) 
> changes. For a reflection from slow to fast, most of the energy is bounced 
> back in phase. from fast to slow, the surface can't return the energy which 
> is reflected back in antiphase as energy has to be conserved. 
> 
> See:
> http://hyperphysics.phy-astr.gsu.edu/hbase/sound/reflec.html 
> 
> An illustration of this effect is with organ pipes which are either closed 
> or open. A closed (stopped) pipe produces a sound one octave lower than an 
> open pipe. 
> 
> David Brinicombe 
> 
> 
> 




Messages in this topic (12)
________________________________________________________________________
1c. Re: underwater stereo recordings and phase
    Posted by: "Dan Dugan"  dandugan_1999
    Date: Tue Sep 1, 2015 11:12 am ((PDT))

> A reflection takes place at a boundary where the speed of sound (or light) 
> changes. For a reflection from slow to fast, most of the energy is bounced 
> back in phase. from fast to slow, the surface can't return the energy which 
> is reflected back in antiphase as energy has to be conserved. 
> 
> See:
> http://hyperphysics.phy-astr.gsu.edu/hbase/sound/reflec.html 
> 
> An illustration of this effect is with organ pipes which are either closed 
> or open.  A closed (stopped) pipe produces a sound one octave lower than an 
> open pipe. 

Thanks for this, David, very helpful.

I’ve only thrown my mics into vernal pools and ditches, so they just fall on 
the bottom and become boundary mics, I suppose, though one could ask what the 
impedance transition is between water and wet mud.

I wonder if in still water putting the hydrophone just below the surface would 
give a boundary mic effect—or since the transition is the opposite direction, 
what would be the inverse of the effect? A suck-out rather than a build-up of 
pressure?

Someone a few days ago remarked that with the static sounds common in ponds 
they didn’t hear any stereo effect, just L and R independent. I wonder if that 
was because the high-frequencies are short-range and there simply weren’t any 
low or mid frequencies present to make any imaging.

-Dan




Messages in this topic (12)
________________________________________________________________________
1d. Re: underwater stereo recordings and phase
    Posted by:   madl74
    Date: Tue Sep 1, 2015 6:28 pm ((PDT))

> I 'think' what Russell is asking is what practical difference does it make. 

Jim, 

I covered that in n earlier email. Underwater, with or without a mic, the 
surface antiphase reflection partially cancels out the direct sound in the 
water, according to the wavelength of that sound which is 4.4 times the 
wavelength we are used to in air. Next time you dive and resurface, listen 
out for the frequency shift of the underwater noises as you approach the 
surface. Either that or dunk a hydrophone and let someone else do the 
diving. :-) 

The thread was about underwater stereo and the problems arising from 
multiple reflections underwater with a 1kHz wavelength being 1.5Metres 
instead of 340cms. 

David Brinicombe 







Messages in this topic (12)
________________________________________________________________________
1e. Re: underwater stereo recordings and phase
    Posted by:   madl74
    Date: Tue Sep 1, 2015 6:58 pm ((PDT))

> I wonder if in still water putting the hydrophone just below the surface 
> would give a boundary mic effect—or since the transition is the opposite 
> direction, what would be the inverse of the effect? A suck-out rather than a 
> build-up of pressure?

Dan, 

Try it and report back. The theory says that when close the negative 
reflection would counter the direct signal. My experience (some time ago) 
was that it sounded better deeper. Must check my own theory out though. :-) 

> Someone a few days ago remarked that with the static sounds common in ponds 
> they didn’t hear any stereo effect, just L and R independent. 

I'm going to buy a pair of JrF hydrophones and check them out as a fig-8 
pair and as a spaced binaural pair at 750cms. The problem I have is that my 
local river is a bit shallow. 

Note; Jez is currently recovering from a car crash so there will be a delay 
on dispatching JrF mics. I'm sending him a get well soon message. 

David Brinicombe 







Messages in this topic (12)
________________________________________________________________________
________________________________________________________________________
2a. New study shows traffic noise is disruptive to wildlife
    Posted by: "J. Charles Holt"  
    Date: Tue Sep 1, 2015 9:26 am ((PDT))

http://m.pnas.org/content/early/2015/08/27/1504710112

"Decades of research demonstrate that roads impact wildlife and suggest traffic 
noise as a primary cause of population declines near roads. We created a 
“phantom road” using an array of speakers to apply traffic noise to a roadless 
landscape, directly testing the effect of noise alone on an entire songbird 
community during autumn migration. Thirty-one percent of the bird community 
avoided the phantom road. For individuals that stayed despite the noise, 
overall body condition decreased by a full SD and some species showed a change 
in ability to gain body condition when exposed to traffic noise during 
migratory stopover. We conducted complementary laboratory experiments that 
implicate foraging-vigilance behavior as one mechanism driving this pattern. 
Our results suggest that noise degrades habitat that is otherwise suitable, and 
that the presence of a species does not indicate the absence of an impact."

- Charles




Messages in this topic (3)
________________________________________________________________________
2b. Re: New study shows traffic noise is disruptive to wildlife
    Posted by:   
    Date: Tue Sep 1, 2015 6:02 pm ((PDT))


Charles,
 
Obviously traffic noise interferes with communication among birds, creating 
problems for defense of territory and self, as well as for mating potential. I 
think I remember reading that this has led to birds, exposed to this noise, 
changing or modifying their songs, as a result. Another aspect of noise 
pollution. We know how it affects us as nature recordists.

All the best,
Ernie Jardine
Pickering Ontario


www.birdsongidentification.com
 
 
-----Original Message-----
From: 'J. Charles Holt'  [naturerecordists] 
<>
To: naturerecordists <>
Sent: Tue, Sep 1, 2015 12:27 pm
Subject: [Nature Recordists] New study shows traffic noise is disruptive to 
wildlife


    
   
    
     
http://m.pnas.org/content/early/2015/08/27/1504710112
 
 "Decades of research demonstrate that roads impact wildlife and suggest 
traffic noise as a primary cause of population declines near roads. We created 
a “phantom road” using an array of speakers to apply traffic noise to a 
roadless landscape, directly testing the effect of noise alone on an entire 
songbird community during autumn migration. Thirty-one percent of the bird 
community avoided the phantom road. For individuals that stayed despite the 
noise, overall body condition decreased by a full SD and some species showed a 
change in ability to gain body condition when exposed to traffic noise during 
migratory stopover. We conducted complementary laboratory experiments that 
implicate foraging-vigilance behavior as one mechanism driving this pattern. 
Our results suggest that noise degrades habitat that is otherwise suitable, and 
that the presence of a species does not indicate the absence of an impact."
 
 - Charles
    
    
 
   





Messages in this topic (3)
________________________________________________________________________
2c. Re: New study shows traffic noise is disruptive to wildlife
    Posted by: "Bernie Krause"  bigchirp1
    Date: Tue Sep 1, 2015 6:21 pm ((PDT))

In Sonoma, California�s Valley of the Moon, there was no birdsong this spring 
or summer. None. A combo of global warming (the spring season occurs on average 
14 days earlier than 20 years ago), bird populations have shifted, and altho 
there have been some calls and other vocal interchange, there has been absolute 
silence as far as song is concerned. I am currently drafting a paper to show 
the effects that have caused it and the consequences.

Bernie Krause

On Sep 1, 2015, at 6:02 PM,  [naturerecordists] 
<> wrote:

> 
> 
> Charles,
>  
> Obviously traffic noise interferes with communication among birds, creating 
> problems for defense of territory and self, as well as for mating potential. 
> I think I remember reading that this has led to birds, exposed to this noise, 
> changing or modifying their songs, as a result. Another aspect of noise 
> pollution. We know how it affects us as nature recordists.
>  
> All the best,
> Ernie Jardine
> Pickering Ontario
> 
>  
> www.birdsongidentification.com
>  
>  
> -----Original Message-----
> From: 'J. Charles Holt'  [naturerecordists] 
> <>
> To: naturerecordists <>
> Sent: Tue, Sep 1, 2015 12:27 pm
> Subject: [Nature Recordists] New study shows traffic noise is disruptive to 
> wildlife
> 
> http://m.pnas.org/content/early/2015/08/27/1504710112
> 
> "Decades of research demonstrate that roads impact wildlife and suggest 
> traffic noise as a primary cause of population declines near roads. We 
> created a �phantom road� using an array of speakers to apply traffic noise to 
> a roadless landscape, directly testing the effect of noise alone on an entire 
> songbird community during autumn migration. Thirty-one percent of the bird 
> community avoided the phantom road. For individuals that stayed despite the 
> noise, overall body condition decreased by a full SD and some species showed 
> a change in ability to gain body condition when exposed to traffic noise 
> during migratory stopover. We conducted complementary laboratory experiments 
> that implicate foraging-vigilance behavior as one mechanism driving this 
> pattern. Our results suggest that noise degrades habitat that is otherwise 
> suitable, and that the presence of a species does not indicate the absence of 
> an impact."
> 
> - Charles
> 
> 
> 

Wild Sanctuary
POB 536
Glen Ellen, CA 95442
707-996-6677
http://www.wildsanctuary.com

SKYPE: biophony
FaceBook: http://www.facebook.com/BernieKrauseAuthor
TED Global talk: 
http://www.ted.com/talks/bernie_krause_the_voice_of_the_natural_world.html













Messages in this topic (3)



"While a picture is worth a thousand words, a 
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.



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