Operation Manual

22 Keyboard Layout
3 Keyboard Layout
Strum Acoustic Session reacts to MIDI signal differently than a traditional synthesizer. It uses a
special keyboard layout and associates signals from standard MIDI controllers with specific effects
or techniques on the guitar. In this chapter, we will describe how the keyboard is used to play Strum
Session.
The MIDI signal received by Strum Session is interpreted in terms of the fretting hand (usually
left hand) and picking hand (usually right hand) of a guitar player. The range of the MIDI keyboard
has therefore been divided into two sections, the Lead & Chord keys section and the Strumming
Keys section as illustrated in Figure 10.
3.1 Lead and Chord Keys
This section is associated with the fretting hand of the guitarist and includes notes ranging from
MIDI note numbers 40 (E1) to 70 (B[4). This section of the keyboard is where melodies and
chords are played and it is the MIDI signal from this section which is sent to the chord detection
and voicing modules. Strum Session will try to detect a chord and find a corresponding voicing
as soon as three keys or more are depressed on the keyboard, otherwise it will play the notes as a
melody or an interval.
3.2 Strumming Keys
Notes with MIDI number ranging between 72 (C5) and 84 (C6) are interpreted as special strum-
ming keys and are used to trigger different picking hand techniques as shown in Figure 10. De-
pending on the strumming keys used one can trigger downstrokes, upstrokes as well as palm muted
or muffled downstrokes and upstrokes. Strings can also be triggered individually to play arpeggio
patterns. The effect of the different strumming keys is now reviewed.
3.2.1 Downstroke and Upstroke
A downstroke is achieved by dragging a pick (or the fingers) across the strings of the guitar in a
downward motion. Notes are therefore played from lowest to highest. An upstroke is obtained in
the same manner but dragging the pick or fingers upwards from the highest to the lowest string.
A downstroke is triggered by depressing MIDI note 72(C5) while an upstroke is triggered by de-
pressing MIDI note 74 (D5). These strokes represent the simplest way to play chords on a guitar
and can be played alternately. Note that when strings are not used in a specific voicing (strings
marked with an X in the chord display of the graphical interface), they are not played when using
a downstroke or an upstroke.