1GDW wrote:
> Walt, Your explanations seem very plausible. Thank you for your
> input. You mention that the old PA systems were more efficient at
> projecting sound. I remember being in the audience of those set ups
> and would note that the sound had a different quality than today's
> sound systems. They would produce sound that was very load but it
> was not pleasant to hear!
Not all such systems were bad. In many cases the bad sounds were
actually either poor mics, or badly maintained speakers being
overdriven. It was possible to have really good sound back then.
Even the hifi systems would sound different. The changes in design of
speakers to handle power have changed the sound they produce. Not
necessarily better or more natural either. But we are pretty much used
to the modern sound. Though my main regular speakers in my living room I
built in the 60's out of some of the last of the old style speakers. I
play them in combo with a pair of magnaplan speakers. And I never crank
my modern amp up to full power, there would be nothing but speaker fuzz
in the room.
> I hope this thread isn't interpreted as a tutorial for field
> playback, my question was directed to possible changes in the sound
> as it is reproduced. Much attention is directed to making a digital
> sample of the sound and very little is discussed about how we play
> it back.
If anything I view it as reminding folks of just how limited playback
really is.
I think most of the group use headphones when they want to carefully
listen to a recording. Lang has brought up some points on trying for
better stereo and surround fields with speakers.
The problems of playing sound with speakers or the quality of the
average person's playing system is why I don't get very excited about
going any more than stereo recording. Few even listen to stereo anything
like correctly.
I view playback as neutral, it's a tool. Tools can be very useful and
needed, and they can be misused. A lot of the negatives about playback
are due to assumptions that a course or two in animal behavior or animal
ethology would change. Or a bit more observation. There are times when
it is misused, particularly when separating tourists from their money is
involved...
As a tool it's well to understand playback and appropriate to discuss it
here.
Walt
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>From Tue Mar 8 18:23:00 2005
Message: 2
Date: Thu, 28 Nov 2002 14:05:18 -0500
From: Walter Knapp <>
Subject: Re: Re: bird song
oryoki2000 wrote:
> Gerald White asked:
>
>>...how much power would it take to
>>replicate a small birds live song?
>
>
> A cassette tape machine like the Sony TCM-5000EV can successfully
> replicate most bird song via its 3.5" speaker with output rated at
> 700mW maximum. A more powerful amplified speaker could be useful
> because it produces the same 700mW with less distortion.
I will repeat, such output may sound the same in a room, or with your
ear at the speaker, but will fall off much more rapidly in the outdoors
than a natural call will. Try checking with a sound meter. Or going out
and walking out for a couple hundred feet.
And the 700mW is not the sound energy produced but is a rating of power
put into the output stage. The actual sound energy is a very tiny
fraction of that.
> Many field recordists object to playback as a means to attract a
> subject. The sounds you record in response to playback probably will
> be angry chip notes as your subject searches for an invisible
> adversary.
I think this highly depends on the species, and how the playback is done.
There are also valid reasons for playback. Though I don't consider
attracting birds for tourists to be one of them. Nor is filling
someone's life list. Which seems to be a far more common use than recording.
For instance, when the Pine Barrens Treefrog was first discovered in the
Florida panhandle, there were 3 known breeding sites, with the typical
number calling. That resulted in some dumb regulators immediately
listing it as highly endangered and rare. It took the dedicated work of
some researchers using calls to show that it was widely distributed in
hundreds of sites. They found those in a single season. And it took even
more effort and time to force the delisting than it took for it to be
listed in the first place.
The southern populations of Pine Barrens Treefrogs, even if there are
pretty good numbers at a site, have a calling pattern that makes survey
very hard. They split up into small calling groups of 3 - 7 individuals
or so. Only one group calls at a time, and they call for a few minutes
about once every 20 - 30 minutes. Their call only carries a short ways
as well. If it were not for them being easy to get to respond to
imitation or playback calls, few sites would be found.
I currently make a imitation call which I will not repeat in public,
it's awful. It does work, I found more than a half dozen sites in one
evening in Alabama that way. I've investigated the carrying power of
speakers for exactly this work. Which is why I know that the speaker
produced calls are very disappointing.
Pine Barrens Treefrogs have only unconfirmed reports in Georgia. There
is considerable chance that they are here. But the area that's
"potential" is about 1/3 or more of the state. So any aid that speeds
the process is something I'll try.
> Using playback is unacceptable in many preserves. Even recording is
> forbidden in some locations (I remember a long conversation with
> INPARQUE staff at Morrocoy National Park, Venezuela. In their eyes,
> using a video camera was OK. But mounting the camera on a tripod
> suggested a commercial intent, which required an expensive license.)
The US national park service had the same sort of rule about tripods
until it was finally beaten down. They were applying it to microphones
too. It took forcing a new written rule. I think we can thank Bernie for
a lot of that.
Walt
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