Question re copying cassette tapes

[Keola Donaghy]

On 2010 Pep. 11, at 19:28, William J Poser wrote:

> Yes, an audio CD must be stereo, 44.1 KHz, 16 bit. But that's not the
> question. If you're digitizing analogue tapes, the data is likely to
> be used in a variety of ways, only one of which is making audio CDs.
> When you want to make an audio CD, if your data is in another format,
> you convert it to the audio CD format, which is easily done. If your
> original recording is monaural, as most linguistic recordings are in my
> experience, there's no point in wasting space and processing time in
> digitizing it stereo (or even worse, as can happen, digitizing one
> channel of voice and another of background noise). If you need a
> "stereo" version for an audio CD, it is a trivial matter to duplicate
> the single channel.

Aloha Bill. To me this is an argument in support of digitizing both channels, or at the very least listening to both sides before digitizing. We have had experience of tapes where there was a significant difference in audio quality between the two sides, or pre-echoes that were more noticeable on one side or the other. It would be easier to have a digitized file that you can more through fairly quickly to compare the two side. Of course for space considerations, the lesser side could be deleted. I've come across one situation where one side was better at the beginning of the tape (some clicking was audible in the better channel toward the end of the tape), and better on the other side at the end. Ended up splicing the two together.

> With regard to higher sampling rates, I agree that they're desirable
> for music, which is of course what the recording industry is concerned
> with, but I repeat that there is not the slightest evidence that anything
> of significance in speech is found above 10Khz. Even if real psychophysical
> experiments rather than anecdotes demonstrate that people can tell the
> difference, the question is, does the difference matter? Piles of evidence
> form psychophysical experimentation together with practical experience
> in both phonetics research and speech technology indicate no.

I can put my faith in research and academic papers or my own ears. I have had audio done as I described - one recorded at 22k and the other at 44.1 and down-sampled. There was a clarity to the second that was not present in the first, and it allowed me to differentiate some sounds that I could not when they were originally recorded at the lower rate. Same equipment, same software. There could be some variable that I don't know about, and it may not be the case for everyone else. As they say, your mileage may vary. I'd recommend to anyone who is going to start an archiving project to experiment broadly. If you can't hear the difference, by all means save the space and extra time it would take to process 44.1 files and go with 22.1. If I still have the files I'll post them, but I kind of doubt it as it was simply experimental and I probably deleted them after we came to a determination and created our system for the project.

In our case, the reel-to-reel tapes were not marked and we had no way of knowing what, if any, noise reduction system was used on them. Took some experimenting, too.

Keola

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Keola Donaghy                                           
Assistant Professor of Hawaiian Studies 
Ka Haka 'Ula O Ke'elikolani             keola at leoki.uhh.hawaii.edu 
University of Hawai'i at Hilo           http://www2.hawaii.edu/~donaghy/

"Tír gan teanga, tír gan anam."  (Irish Gaelic saying)
A country without its language is a country without its soul.
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