> > 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.
WALT
>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.
To compare sound levels they have to be measured at the same distance
in the same environment. I doubt that the output level of a
recorder's speaker is anywhere near as loud as a bird. It "sounds the
same" at one meter, but remember the bird is singing five meters from
you, not one meter, and sound level falls off by the inverse square
of the distance. At one meter the bird would be a lot louder! The
difference between one meter and five meters distance, for example is
14 dB.
-Dan Dugan
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>From Tue Mar 8 18:23:00 2005
Message: 13
Date: Fri, 29 Nov 2002 02:59:24 -0500
From: Walter Knapp <>
Subject: Re: x-rays & reel-to-reel tape
Aaron Ximm wrote:
> Happy Thanksgiving, all who celebrate it tonight;
>
> ...and a question: visiting my mother in Seattle. She found and is giving
> me a box of reel-to-reel tapes from the 70's which include my first
> burblings (now there's a recording! I wonder what mic they used...) and my
> folksinger uncle Art [Thieme] performing live around that time. These are
> irreplaceable, needless to say, and I'm wondering how best to get them
> back to SF with me.
>
> Might they be safely X-rayed at the airport tommorow? I *assume* so and
> don't imagine they do any sort of magnetic imaging... but I'd hate to be
> wrong and harm/ruin the tapes. The deck I figure I can always eventually
> replace (if it's damaged in transit).
>
> Thought I'd query the Group-mind on the off chance anyone's still up at
> this hour!
Xrays per se should not bother them. But to produce Xrays fairly large
amounts of electricity and magnetic fields are involved. I don't know
how much risk there is other than that thought.
I would tend to just pack them up and have UPS cart them. With thick
padding they would be pretty safe. Airports are getting less safe all
the time, and I don't mean from terrorists.
Walt
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