Transferring audiotaped speech to CDs

[Celso Alvarez Caccamo]

(WARNING: LONG MESSAGE)

Marcia and all,

Debrah Spitulnik recently posted a similar query in LINGUIST and then sent
a summary to the list with a bunch of replies. I also sent her a long,
private mail with more info, but she never replied. I have some experience
digitalizing audio. Briefly, these are the steps:

1) Good tape-player connected to good audio card in desktop PC
(laptops add more noise, in my experience). Noise that goes in,
noise that stays on and needs to be cleaned.
2) Fast processor and lots of hard drive memory: about 650MB per
hour of sound. Fast processor to avoid clicks and other artifacts
from reading-writing operations in hard drive.
3) Versatile, easy to use software. For PC, among the best is CoolEdit.
Goldwave is good too. Sound software generates WAV files.
4) Digitalize at 44Kh, stereo, 16 bits -- that's the format for
CD audio tracks. No, you can't save space by digitalizing at mono
even if the original recording is mono. As a matter of facts, audio-CD
tracks cannot have only one channel.
5) Set recording volume as high as possible without sound distortion.
6) CD recorder, of course. NOT re-writeable CD's.
7) Software to burn audio CD's, of course. I use EasyCD maker. This type
of software converts WAV files to audio-CD CDA files.
8) Lots of tests, time, and patience.

TIPS:
--In longer conversations, try to splice speech stream in shorter
fragments. Some utilities do that at a click of the mouse. When burning
the audio tracks, you'll have the option of adding a 2-second silence
between tracks or writing them continuously. I recommend the second option
for longer conversations, so that you don't have huge files, much harder
to clean, etc. When playing back the audio CD, you won't notice cuts in
the middle of the conversation, even when jumping from track to track.

--Do not digitalize with Dolby on or other sound filters, unless you're
absolutely sure you don't mind losing some speech qualities that later you
won't miss for speech (spectrographic, etc.) analysis. You can always make
various digitalized versions of samples for various purposes.

--Test several CD brands before going for a given one. You should choose
the one that sounds better for your CD-recorder but also that plays fine
in most CD players. Even though it may sound like magic, some coatings
muffle the sound (in my experience a yellow-coated CD is worse, best are
light-bluish/silver). My favorite CD's are Fuji (Silver). TDK are OK.
SONY are bad, sorry. Also, do not use those CD's that claim to store 80
minutes of sound instead of 74 -- that's perhaps physically possible, but
softwareably tricky. The medium is the medium (not the message ;-) ), and
74 minutes is all you can fit in a CD-sized CD.

--Also, do repeated playbacks of each brand in a conventional CD player
to make sure the coating does not deteriorate with time. Don't tell me
why, but some BASF CD's that sounded excellent at first started
developing all sorts of clicks and CD's became unusable.

--Be aware that not all regular computer CD's play fine in any CD player.
The only ones that work across the board are the expensive ones, only for
sound. But for that you need an AUDIO CD-recorder, with a regular analog
input line. The procedure is then totally different, you can't make copies
of those audio-CD's in your computer, etc. I've been told that, whereas
nowadays most CD players play computer-burned audio-CD's, the truth is
that the angle of reflection of the laser beam in computer-burned CD's
differs from that of commercial or audio-CD's. The CD-player must make
constant corrections in the laser beam that in the long run may either
damage the player mirrors (myth?) or damage the CD (?).

--Keep copies of the original WAV files as such (not as CDA files) in
another set of CD-ROMs. You never know in which direction technology may
develop.  When DVD-recording gadgets become more available and cheaper (so
cheap that they'll only cost about a year's salary for an immigrant street
vendor in Madrid), we may be able to burn audio DVD's from these files. It
is true that CD's deteriorate with time, if played repeatedly. But if you
keep the original WAV files even in another medium, better. Solid memory
(chips) is the way to go, but it's still very expensive, and soon we will
learn that it's also perishable (what isn't?), so the only medium that
always remains is human memory, which sometimes is more faithful to real
events than real events are.

--It's also true, as Barbara says, that in digitalizing sound you miss a
bit here and there. But you'll probably never notice ;-).

All in all, doing this is a lot of fun. I would also like to hear more
about it.  Every time this topic comes up I learn something new, which is
great to keep me away from learning about The Real Stuff. If anyone needs
a Sound Digitilizer Assistant... ;-) .

Best,
-celso
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Celso Alvarez Caccamo              Tel. +34 981 167000 ext. 1888
Linguistica Geral, Faculdade de Filologia     FAX +34 981 167151
Universidade da Corunha                          lxalvarz at udc.es
15071 A Corunha, Galiza (Espanha)  http://www.udc.es/dep/lx/cac/
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