Information Technology Reference
In-Depth Information
nition of a network that generates a valid sentence with a
beginning and an end, including real-time EEG control through the variable EEG-
SET-COMPOSER. The algorithm will
Above is a de
find a musical element in the database for
each of the constraint sets that are generated above from INC and BAR, by applying
the list of constraints in left-to-right order to the set of all musical elements until
there are no constraints left, or there is only one musical element left. This means
that some of the given constraints might not be applied.
The database of all musical elements (see Appendix for a short example) con-
tains music from different composers, with elements tagged by their musical
function such as
measure 1
for the start of a phrase,
cadence
for the end,
composer
for the name of the composer and the special tags
pitch
and
pitch
-
class
that are both
used for correct melodic and harmonic progression or direction. The selection
process is illustrated below.
The example database in the Appendix shows the main attributes that are used to
recombine musical elements. P-CLASS (for
pitch
-
class
) is a list of two elements.
The
first is the list of start notes, transposed to the range of 0
11. The second is the
-
list of all notes in this element (also transposed to 0
rst
(and highest) melodic note in this element, by matching this with the melodic note
that the previous element was leading up to we can generate a melodic
11). P is the
pitch
of the
-
ow that
adheres in some way to the logic of how the music should develop. The PCL (for
pitch
-
class leading
) elements contain the same information about the original next
bar; this is used to
find a possible next bar in the recombination process. Then, there
are the INC, BAR and CAD elements. These are used for establishing whether
those elements can be used for phrase starts (incipient), or cadence.
Simply by combining the musical elements with the constraint-based selection
process that follows from the terminals of the phrase structure rewrite rules, we
obtain a generative method that can take into account the EEG information. This
generates musical phrases with building block connectivity like a domino game:
((EQUAL
'
MEASURE 1)
(EQUAL
'
COMPOSER EEG-SET-COMPOSER))
Assuming that there are also musical elements available from composers other
than SCHU, the
first constraint will limit the options to all
incipient
measures from
all musical elements from all composers. The second constraint will then limit the
options according to the current EEG analysis to the composer that is associated
with the current EEG activity as follows:
((CLOSE
'
PITCH
'
PREV-PITCH-LEADING)
(CLOSE
'
PITCH-CLASS
PREV-PITCH-CLASS-LEADING)
(EQUAL
'
'
COMPOSER EEG-SET-COMPOSER))
