limitations of MD

[Larry Gorbet]

P L Patrick <patrickp at essex.ac.uk> wrote

>	In a pinch I prefer to add noise (with analog recording) rather
>than to subtract elements of the authentic speech signal (with MD).

Without specific recorders (etc.) and specific encoding algorithms
(for the MD), this preference is a little hard to evaluate.  But in
the most general case, "noise" and the "subracting elements of the
authentic speech signals" are indistinguishable.  Magnitudes involved
are clearly critical:  if I had sufficient noise of the right (i.e.
wrong) type, *all* elements of the speech signal in affected parts of
the spectrum would be gone, undetectable.

>	DAT tapes are modern tapes, however, without the vulnerability
>to magnetic fields that magnetic tapes have. Magnetic tapes are indeed
>the longest-lasting format we have so far, and have been recovered from
>undersea and found to still contain information. The last 15 years have
>seen a lot of knowledge in tape construction, so DAT tapes are probably
>a pretty good bet too.

I'm not *quite* sure what this means.  DAT tapes *are* magnetic
tapes.  Is *analogue* magnetic tape meant?  I have a very hard time
believing that magnetic tapes are the longest lasting format we have
so far.  In fact, I know that's not strictly speaking true, since we
have recordings that are older than any magnetic recordings.  If
instead of the past, we look forward, then it is highly likely that
*some* types of CD recordings pressed in commercial factories will
last longer by far than any traditional magnetic media.  That's even
more true if we suppose storage in the environments that most of what
we might record in field research are likely to experience.  If I had
to record something that I thought was inestimably important to
preserve in the finest detail, while working in a fairly remote
location, I'm pretty sure that it would be done on a good DAT
recorder, with the best mic and cabling I could muster, and would,
upon returning to home, get transferred as quickly as possible to
some kind of optical media (multiple copies).

In the more real world, I strongly second the emphasis on microphones
(and microphone technique).  For most purposes, I'd rather have
pretty good cassette or MD and a really good mic appropriate to the
particular recording than a cheap so-so mic and the best DAT recorder
that money could buy.

- Larry
--
Larry Gorbet                         lgorbet at unm.edu
Anthropology & Linguistics Depts.    (505) 883-7378
University of New Mexico
Albuquerque, NM, U.S.A.