Operation Manual

2.2 Strumming 19
2.2 Strumming
On a guitar, notes and chords are triggered by the action of the picking hand (usually right hand).
The resulting sound is very typical of a guitar as the guitarist triggers the strings sequentially, more
or less rapidly, with an up and down motion of the hand. Strings can also be played individually,
in different order, to create arpeggio patterns. Different sonorities can be obtained by damping
or muting the strings either by applying the picking hand on the strings near the bridge (palm
muting) or releasing the pressure on the notes played with the fretting hand (scratching) while
strumming. Using these different types of hand motions and techniques, the guitarist can create
complex melodic and rhythmic patterns. In Strum Session, these different effects can be achieved
through a strumming module which is controlled by special strumming keys or MIDI loops as will
be explained in more details in Chapter 3, 4 and 6.
2.3 The Graphical Interface
The graphical interface of the instrument is divided in three sections. From top to bottom on the
interface one first finds the output effect section which is used to shape the final sound of the
instrument. This effect section includes and equalizer and a reverb.
The middle guitar-shaped section of the interface is where all the parameters controlling the
synthesis engine are located. The different control parameters refer to the strings, the pick, and the
body of the guitar.
The bottom part of the interface is centered around a fretboard where the chords detected and
the specific voicings chosen by Strum Session are displayed. This section of the interface also
includes parameters determining how the voicing and strumming is performed by Strum Session,
a MIDI loop player, tuning parameters and controls determining how signals from some standard
MIDI controllers are interpreted by Strum Session.
2.4 Signal Flow
The general signal flow of Strum Session is presented in Figure 9 and illustrates schematically how
the different modules in Strum Session interact. From left to right, the synthesizer first includes a
chord detection module which parses the MIDI signal it receives and determines the chords played
on the keyboard. This information is then sent to the voicing engine which, taking into account
how a guitarist would actually play the different chords, determines which notes are played on the
different strings of the guitar. The corresponding information, for each of the six strings of the
instrument, is then sent to a triggering or strumming module which generates an excitation signal
for each of the individual string. This is the signal received by the synthesis or string module
which then simulates the vibration signal of the individual strings of the guitar. The output of this
module corresponds to the signal that would actually be measured at the bridge of the instrument
and which is transmitted to the body of the instrument. The body module completes the instruments
and simulates how sound is radiated both from the top-plate of the body (or soundboard) and the