Digitizing cassette tapes

[Keola Donaghy]

My final (I hope) contribution to this topic ;-)

We should also conciser the Nyquist-Shannon theorem, which states:

If a function x(t) contains no frequencies higher than B hertz, it is completely determined by giving its ordinates at a series of points spaced 1/(2B) seconds apart.

Essentially, you should sample at twice the rate of the highest frequency you will find in your recording. As Bill mentioned, if the highest frequency that human ears can hear is @ 10k, and we divide 22k by 2, 11k is the upper limit. Beyond that you get some aliasing. For human ears, probably not a problem. How about for as-yet unwritten computer software for transcription that can analyze such data, or better noise reduction algorithms that we have today? I dunno. I would still prefer to be safe and keep a copy at the higher rate. The 96k/24 bit standard Nick cites may be overkill, but somewhere down the road our grandchildren may be grateful that it was done for reasons we don't yet comprehend.

KD


On 2010 Pep. 12, at 10:58, Nick Thieberger wrote:

> An issue that hasn't yet been discussed in relation to digitising old
> tapes is that it should only be done once. This may sound strange, but
> I know of several projects where a 'trial' digitisation occurs, at low
> resolution. These files then become the basis for timecoded
> transcripts and then, later, the project decided they needed archival
> versions of the media and redigitised to international archival
> standards (96khz/24 bit. Yes, I know ths is overkill but it is the
> standard). Of course, the timecoded transcripts no longer match the
> newer, higher resoluion versions.
> 
> Another motivation for doing it right the first time is that the tapes
> themselves may not survive more than one playback (although this is
> rarely the case).
> 
> Nick
> 
> Project Manager
> Pacific and Regional Archive for Digital Sources in Endangered
> Cultures (PARADISEC)
> http://paradisec.org.au
> 
> On 13 February 2010 04:27, Rudy Troike <rtroike at email.arizona.edu> wrote:
>> Howdy,
>> 
>>  Thanks to everyone for the valuable suggestions and discussions re
>> converting these cassette tapes to CDs. I really appreciate all the input.
>> FYI, the tapes in question were made in the late 1960s, as part of the
>> East Texas Dialect Project, recording schoolchildren in East Texas schools
>> scheduled for integration, to prepare materials for teacher training in
>> advance of the integration. They are historically valuable, and I hope
>> someday to be able to interview some of those who were recorded to find if
>> there have been any changes in their speech during their lifetimes.
>> 
>>  Many thanks again,
>> 
>>  Rudy
>> 



========================================================================
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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