Re: mini-disk or DAT? (Sheila Williams )

Subject: Re: mini-disk or DAT?
From:    Sheila Williams  <williams(at)PSYVAX.PSY.UTEXAS.EDU>
Date:    Thu, 21 Jan 1999 09:38:36 -0600

Dear list,

I would like to thank everyone for the information and comments they sent
me for my enquiries on Minidisk vs. DAT and will give a brief summary here
in response to Christel's enquiry.

There was a lot of information so I may be able to post a more complete
summary later.

Apologies in advance if I may have misunderstood any of the
comments/technical information.

Christel asked:
>I'm about to start a series of experiments on voice quality, and am
>planning to use a portable mini-disk recorder to record speech from
>subjects with. Afterwards I intend to carry out some acoustic analysis on the
>speech samples, including harmonic-to-noise ratios and jitter and shimmer
>measurements, among other things.
>
>However, it has been brought to my attention that, if one wants to do
>acoustic analysis on the recorded speech, it may be preferable
>to use a DAT-recorder instead.
>

The overall response to my enquiry was a resounding - Minidisk is good for
recording things to be listened to as it gives high perceptual quality and
long-lasting recordings.

However, and this is a BIG one, in order to avoid use for copying
commercial recordings, Minidisk technology incorporates input filtering and
data compression strategies deliberately designed to distort the signal in
subtle ways which makes the signal more difficult to analyse and impossible
to make accurate measurements of - it also leads to perceptible distortion
if multiple copies are made, so DAT is much better for accurate measurement.

DATs mostly (or all) come with the ability to switch off any such
compression factors.  However, tape media is less robust so should be
archived.

Advice on microphones included use of "cardiod" microphones to get a
general directional background filtering effect without the need for
precise directionality and to use headset mics to maintain distance (to
ensure any  amplitude fluctuations are due to the speaker and not the
distnace).

There are devices out there for converting from optical to coax
input/output for data trandfer.  Decks for rack-mounting seem more likely
to have coax digital ports already, avoiding the need for these devices.

thanks again for all the advice.  For our purposes, which include analysis
and resynthesis of speech recordings, we will definitely be going with DAT
and I am now investigating the relative costs/benefits of the different
systems currently available before we choose our set-up.

I'll try to provide a more technical summary (and a list of all the
contributors), including a comparison of the different systems I can find,
when I've had the chance to wade through all the technical data.

Sheila


Dr Sheila M Williams                            phone: 512-471-4253
Psychology, University of Texas at Austin       lab:   512-471-0693
528 Mezes Hall, Austin, Texas, USA, 78712       fax:   512-471-6175