Identifying Saxophonists from Their Playing Styles - Intelligent Music Information Systems: Tools and Methodologies - page 112

( AtackLev, SustDur, SustSlo, LegLeft,
LegRight, EnergyM, SpecCen, SpecTilt )

due to exposure to music throughout our lives
and familiarity with musical styles and particular
melodies. According to Narmour, any two con-
secutively perceived notes constitute a melodic
interval, and if this interval is not conceived as
complete, it is an implicative interval , that is, an
interval that implies a subsequent interval with
certain characteristics. That is to say, some notes
are more likely than others to follow the implica-
tive interval. Two main principles recognized by
Narmour concern registral direction and interval-
lic difference . The principle of registral direction
states that small intervals imply an interval in the
same registral direction (a small upward interval
implies another upward interval and analogously
for downward intervals), and large intervals imply
a change in registral direction (a large upward
interval implies a downward interval and analo-
gously for downward intervals). The principle
of intervallic difference states that a small (five
semitones or less) interval implies a similarly-
sized interval (plus or minus 2 semitones), and a
large interval (seven semitones or more) implies
a smaller interval. Based on these two principles,
melodic patterns or groups can be identified that
either satisfy or violate the implication as pre-
dicted by the principles. Such patterns are called
structures and are labeled to denote characteris-
tics in terms of registral direction and intervallic
difference. Figure 5 shows prototypical Narmour
structures. A note in a melody often belongs to
more than one structure. Thus, a description of
a melody as a sequence of Narmour structures
consists of a list of overlapping structures. We
parse each melody in the training data in order to
automatically generate an implication/realization
analysis of the pieces. Figure 6 shows the analysis
for a melody fragment.

• Contextual (internote) features. The con-

textual features represent both properties
of the note itself and aspects of the musical
context in which the note appears. Informa-
tion about the note includes note pitch and
note duration, while information about its
melodic context includes the relative pitch
and duration of the neighboring notes (i.e.
previous and following notes) as well as
the Narmour structures to which the note
belongs. The note's Narmour structures
are computed by performing the musical
analysis described in Section 4.2. Thus, each
performed note is contextually characterized
by the tuple

( Pitch, Dur, PrevPitch, PrevDur, NextPitch,
NextDur, Nar1, Nar2, Nar3 )

musical analysis

It is widely recognized that expressive perfor-
mance is a multilevel phenomenon and that
humans perform music considering a number of
abstract musical structures. As a first step towards
providing an abstract structure for the recordings
under study, we decided to use Narmour's theory
of perception and cognition of melodies (Narmour,
1990; 1991) to analyze the performances.
The Implication/Realization model proposed
by Narmour is a theory of perception and cognition
of melodies. The theory states that a melodic musi-
cal line continuously causes listeners to generate
expectations of how the melody should continue.
The nature of these expectations in an individual
are motivated by two types of sources: innate and
learned. According to Narmour, on the one hand
we are all born with innate information which
suggests to us how a particular melody should
continue. On the other hand, learned factors are

algorithm

One of the first questions to be asked before at-
tempting to build a system to automatically iden-