Wow, didn't that spark a flurry!
I would like, if possible, to get back to Vitor's
question. Vitor, there is usually a reason why there
is a very ample price range in speakers (or anything
else, for that matter). Frequency range, frequency
response curve, intensity, distortion levels, internal
noise levels, to mention a few, are all factors that
influence the quality of sound output (and price).
Depending on what you need to do, a cheap speaker may
be all you need. However, for scientific analysis, and
in order to make results reliable, ideally we would
like to know that what we are recording is as close a
fit to what is being emitted. Likewise, we would like
to know that the response that is being generated when
the subject is exposed to a specific stimulus (i.e
playbacks), is because the stimulus is what we think
it is, i.e. with all its spectral and amplitude
components as we observed them before outputting the
signal through the speaker.
If the signal is altered in any significant way when
it goes through the speaker (e.g. artificially
enhancing some frequencies and attenuation of others),
how do you know that the animal is responding in a
characteristic way? It is also possible that an animal
may respond to what it perceives to be a "supersignal"
(depending on how much change the signal undergoes),
and not a normal signal.
In any case- unintentionally altered signals are
distorted signals, and your subject may be responding
to an unnatural signal to begin with.
You can calibrate your equipment via a few tests to
assess whether what you are getting is what you expect
to get. If you like, when you get back from your field
trip drop me a line and we can chat some more about
this.
Bom trabalho de campo,
Ariadne.
--- Vitor Piacentini <> wrote:
> Chuck,
>=20
> I agree with you that for scientific purposes one
> should get good and more expensive equipament.
> That's why I had to save money for 2 years untill I
> could buy a Sennheiser me66/k6 and a Hi-MD recorder
> (wich allow me to do pretty good recordings that fit
> the requirements of virtually all scientific
> bioacoustic studies related to birds). But I still
> cannot see any difference, from a scientific point
> of view, of a bird responding to playback done with
> a 200 $ speaker or responding to a playback done
> with a not-so-wonderful-but-yet-good 13 $ Radio
> Shack speaker. The result is the same: the bird
> responding!
>=20
> Unfortunatelly I have to pack my stuff for a field
> trip and cannot discuss this subject with more
> detail. But I'll try to access internet somewhere
> someday in the next 2 weeks so I can read any
> further message on this issue. Regards,
>=20
> Vitor
>
> >>
> I've seen some pretty "bad" equipment that works
> great for calling
> in birds. I have a friend who went on an expensive
> birding trip where
> the leader used a cheap Radio Shack cassette
> recorder with a built-in
> mic ($40? $30?). The question is, what is suitable
> for scientific
> research and/or making recordings that please human
> beings? *Those* are
> the expensive categories.
>
> -- Chuck
>
> >
> >=3D=3D=3D=3D=3D=3D=3D=3D
> >Chuck Bragg, Pacific Palisades, CA
> >Membership, Newsletter, Web manager
> >Santa Monica Bay Audubon Society
> >www.smbas.org
> >=3D=3D=3D=3D=3D=3D=3D=3D
> >
>
>
>
>
>
> --------------------------------------------
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