Re: [ARSCLIST] Dynamic-frequency Range

[Don Cox <doncox@xxxxxxxxxxxxxx>]

On 21/10/06, Steven C. Barr(x) wrote:

> In actual fact, what we have in any "vintage" recording (it
> could be argued in ANY recording!) is a fraction of the actual
> sound which occured when the recording was made.
> 
> For this reason, ANY "improved" or "reconstructed" version of
> that sound recording is...in fact, MUST be...based at least in
> part on guesswork (insofar as what can't be heard in the recording).
> So, the task of the program creators becomes increasing the
> accuracy of those guesses.
> 
> One interesting approach (and here I speculate) would be to
> duplicate, insofar as possible, the hardware and environment
> used for the original recordings...and then simultaneously
> record something using both old and new technology? This would
> allow us to create an algorithm based on the difference between
> the two recordings and apply that to existing "old" recordings
> to re-create what the "new" version must have sounded like...

Astronomers have a process called "deconvolution" to sharpen up the
images from telescopes. This is based on the fact that you know the
image of a star should be an almost infinitely small point. By comparing
this to the actual blurred and ripply image on the plate (or sensor
chip), you can process the image in a computer to remove some of the
corrupting effects of the optics.

Likewise, one could record sharp clicks (the sound of a spark is ideal)
onto both modern equipment and Edison cylinders (or whatever), and
derive a suitable deconvolution function for the particular combination
of room, horn and cutter.

Whether that would be close enough to help with a recording made in a
different room with a different horn, I don't know. It might well help
somewhat. 

I think it would be necessary to digitise at a high sample rate and
remove as much noise and scratches as possible first.

Regards
-- 
Don Cox
doncox@xxxxxxxxxxxxxx