CHAPTER 23. LIVE INSTRUMENT REFERENCE
432
The modelled string can be played using different types of excitators in order to reproduce
different types of instruments and playing techniques. The excitator is selected using
the Type chooser, and the choices available are
Bow
,
Hammer
,
Hammer (bouncing)
and
Plectrum
.
Bow
- this excitator is associated with bowed instruments such as the violin, viola or cello.
The bow sets the string in sustained oscillation. The motion of the bow hair across the string
creates friction, causing the string to alternate between sticking to the hair and breaking free.
The frequency of this alternation between sticking and slipping determines the fundamental
pitch.
The Force knob adjusts the amount of pressure being applied to the string by the bow. The
sound becomes more scratchy as you increase this value. The friction between the bow
and the string can be adjusted with the Friction control. Higher values usually result in a
faster attack. Velocity adjusts the speed of the bow across the string. Finally, the Vel and
Key sliders below these three controls allow you to modulate their behavior based on note
velocity or pitch, respectively.
Hammer
and
Hammer (bouncing)
- these two excitator types simulate the behavior of soft
hammers or mallets. Hammer models a hammer that is located below the string and strikes
it once before falling away. This type of mechanism is found in a piano, for example.
Hammer (bouncing) models a hammer that is located above the string and is dropped onto
it, meaning that it can bounce on the string multiple times. This playing mode can be found
on a hammered dulcimer, for example.
The mass and stiffness of the hammer are adjusted with the (surprise) Mass and Stiffness
knobs, while Velocity controls the speed at which the hammer is struck against the string. As
with the Bow excitator, these three parameters can be further modulated by note velocity
and pitch by adjusting the Vel and Key sliders. The behavior of the hammer is further
controlled by the Damping knob, which adjusts how much of the hammer's impact force
is absorbed back into the hammer. It is somewhat analogous to the Stiffness parameter,
but instead of controlling the stiffness of the hammer's surface it adjusts the stiffness of
the virtual spring that connects the hammer to the mass that powers it. As you increase
the Damping amount, the interaction between the hammer and string will become shorter,
generally resulting in a louder, brighter sound.
Plectrum
- a plectrum or pick is associated with instruments such as guitars and harpsi-
chords. It can be thought of as an angled object placed under the string that snaps the
