Adaptive Tunings

I wrote:

>>One thought: personally, I think I
>>would be more or less content if this could be implemented as a
>>convenient 'post-production' technique. But people who are
>>interested in using these machines for live performance would
>>presumably want more than this?

Bill Sethares wrote:

>All of my adative tuning work has been "off-line". I make a standard
>MIDI file, read it into my adaptive algorithm, wait a while, and
>then check out how it did. This is a very awkward way to work, and
>is essentially a kind of 'post-production' method as you describe. I
>think adaptive tunings will only be really useful when you can sit
>down and play as if it were a musical instrument. Such
>'post->production' methods are fine for demonstrating the concepts,
>but not >for exploring the technique fully.

I agree with Bill that real-time adaptive tunings would be best.

I guess quite a few people on the list will be familiar with
John S. Allen's Key Concepts prototype Notebender keyboard. I only
know of it from reading JSA's web pages. It allows variable
intonation for a keyboard by 'undercutting' the black keys, so that
both black and white keys can slide (with finger pressure) to and
from the player - these movements are then tranmitted as pitch
changes. JSA says this arrangment is less easy to control than a
traditional keyboard, but easier than clavichordal intonations.

However, a configurable, automatic system, with can be modified or
overriden by physical input would be better.

>I'm currently attempting a 'real-time' version using Max, though its
>unclear at the present time how many simplifications are going to be
>needed before it will actually run in real time. Of course, this is
>for MIDI instruments only. A far more interesting thought is the
>idea of operating on acoustic sounds...

As regards acoustic instruments, I have been writing up a few ideas
on this in the 21C Orch Instrs paper - particularly my idea of
creating an instrument (woodwind or brass) which may switch at will
between adaptive (fixed-but-variable, its normal condition) or fixed
intonation; and conceivably, between a number of ATS.

Firstly, I've mentioned before Giles Brindley's Logical Bassoon - a
purely acoustic instrument in which the 18/19th century keywork is
replaced by a system of solenoid driven tone-hole pads. Professor
Brindley is still playing this instrument every week in an
amateur orchestra in London. (Brindley is a famous neurophysicist,
not an instrument maker). I've spoken to him on the phone, but have
yet to see the instrument(s) - I think he built 3 of them.

Lets take this a step further. Here's one of my crazy ideas - and a
short dump from the paper. I'd certainly appreciate any feedback on
this idea. Would it work???!!!

EXTRACT STARTS *********

Concieve a 'logical' woodwind in which an internal electronic pitch
sensor provides feedback (via software) to a auto-corrective venting
mechanism in real-time. The instrument would be 'self-correcting'
within certain configurable tuning limits; further, this might be
applied in a number of ways, for example, to achieve_ strict_
temperament, or to achieve _strict_ just intonation in any key (at
will). For large n-division systems the system could ensure that
the instrument is always at one pitch or another of a temperament,
making performance more reliable; for JI systems, this would
function similarly, but an on-board switch would tell the software
which pitch is 1/1 at any given time.

Real-time (instantaneous) digital pitch correction for audio has been
available for some years, for example, as part of the ProTools digital
audio processing suite (recently released in rack-mount form as the
Antares Auto-Tune). [Anyone have good/bad experience of this??]
A performance by a singer or instrumentalist can be instantaneously
'corrected' so that all inflections adhere strictly to a given tuning
system. The Antares allows custom scales, but the typical
implementation is strict 12-ET. This runs counter to the norm of
variable intonation (for singers, wind and brass etc.), but more
sophisticated realisations are clearly possible - for example, in its
current version the Antares is able to 'ignore' vibrato and
glissandi.

The suggestion here is not to use such a mechanism to translate an
acoustically produced sound into a digitally modulated one, but to
feedback corrections of the electronically monitored pitch signal to
the tone-hole closure system of the acoustic instrument. The player
would thus be in constant dialogue not only with the vibrations of the
instrumental system, but with extremely fine adjustments of tone-hole
closure being carried out independently by the corrective process.
This would require the finest possible balance of sensitivity and
stability in terms of software interactivity, since unless pitch
adjustments were fine, unwanted glissandi and suchlike would result;
on the other hand, extreme subtleties of pitch inflection should not
be overridden, and the player would need to be able to vary the
sensitivity of the device (from 0 -100% ) at the slightest touch of a
key.

EXTRACT ENDS ************

If this could be made to work on a woodwind, it is conceivable it
could also work for brass too - this time the interactivity taking
place through a slide mechanism (maybe driven by a tiny stepper
motor??)

The important aspect of this is that the physical interface is
replaced by a virtual one. (By the way, in the case of woodwind and
brass, the most important (personal) aspect of 'contact' with a
*keyed* (or valve) instrument is the mouth: the performers of
'logical acoustic instruments' report no loss of 'feel' or
sensitivity).

In addition, an adaptive acoustic piano could be made by creating an
instrument with a very large number of unison string groups, and the
keyboard transmits via a Disklavier type piano action which is
controlled by 'adaptive' software.

Patrick O-L

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End of TUNING Digest 1463
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I've not received a reply yet, since the "applelink" address doesn't seem
to work.
I have got another address and have resent my message.

Here is the URL and e-mail "



Later,
Drew

"I will not speculate today
with poems that think they're money."
-Anne Sexton, from 'January 1st'.