APPLIED ACOUSTICS SYSTEMS STRINGSTUDIO Manuel d'utilisateur télécharger pdf (Page 26)

26 Parameters

Damp knob, and controlling the absorption of the impact between the string and the hammer by

the hammer. Note that this parameter is not related to the decay time of the string oscillation or the

overall sound. On the contrary, the effect of this parameter may sometimes seem counter-intuitive

even if it reproduces a physical property of the hammer. For example, increasing the damping of

the hammer will make the compression of the spring linking the head to the mass harder and which

will shorten the interaction between the hammer and the string but will also make it appear stronger

resulting in a louder or longer sound.

Damping

Mass

Stiffness

String

Velocity

Damping

Velocity

Mass

Stiffness

String

Hammer 1 Hammer 2

Figure 10: The two Hammer modes

Bow

The Bow exciter is used to play bowed instruments such as the violin, viola, or cello. The role of

the bow is to set the string in self-sustained oscillation. Physically, oscillations of the string are

maintained by a regular cycle of stick-slip movements. Due to friction forces between the string

and the bow, the string sticks to the bow and follows its motion until the tension forces in the string,

due to its own oscillating motion, break it free from the bow. The string is then in its slip phase and

moves in the opposite direction to that of the bow. When the string motion changes direction once

more, it sticks to the bow again, moving with the bow until it breaks free and repeats the cycle.

Note that the frequency of this stick-slip motion is exactly the same as that of the string oscillation;

or, in other words, the pitch of the note played.

The force with which the bow is applied on the string can be adjusted with the Force knob, the

friction between the bow and the string is set with the Friction knob, and the velocity of the bow

is controlled with the Velocity knob. Note that the damp knob is inactive when the bow exciter is

selected. The tone and behavior of the instrument are the results of a complex relationship between

these parameters but some general rules can however be followed. As the force applied by the bow

on the string is increased, the tone becomes more scrubby. The friction between the bow and the

string usually determines the length of the attack; the greater the friction, the faster the string can

be set into motion. Finally, the velocity is related to the amplitude of the sound.

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APPLIED ACOUSTICS SYSTEMS STRINGSTUDIO Manuel d'utilisateur Page 26