Operation Manual

6.43 Membrane 105
Figure 57: A Master Sync Input is used to synchronize a Multisequencer module.
6.43 Membrane
The Membrane module simulates sound production by rectangular membranes of different ma-
terials and sizes. This module first calculates the modal parameters corresponding to membrane
shaped objects according to the value of the different parameters requested at construction time
and, next, calls the Multimode module to simulate sound production by this object. The module
has one output, the sound produced by the membrane, and three inputs. The first input signal is
a damping signal which, depending on its value, lowers or raises dampers on the structure. When
the input signal is equal to 0, dampers are lowered on the membrane, thus shortening the decay
time of the sound produced by the structure. When the signal is greater than 0, dampers are raised.
Note that this damping is in addition to the natural damping of the membrane itself. If this input is
not connected to any other module, the default value is set at 0, which implies that the membrane
motion will be damped. This input is, therefore, usually connected to a Constant module to obtain
undamped motion or to a Damper module or the gate signal from a keyboard in order to vary the
damping while playing. The second input signal is the force signal exciting the membrane, while
the third is a pitch modulation signal.
The default value of the following parameters is set at construction
• Length: the length, in meters, of the membrane.
• Width: the width, in meters, of the membrane.
• Frequency: fundamental frequency, in Hertz, of the membrane when there is no pitch mod-
ulation signal or when its value is equal to 0. Note that the fundamental frequency is in-
dependent of the size of the membrane. The software automatically calculates the physical
parameters necessary to obtain the required fundamental frequency. The default value of this
parameter is 261.62 Hz, which corresponds to the middle C (C3) of a piano keyboard. This
setting is convenient when controlling a Membrane module with a Keyboard module.
• Decay: proportional to the decay time of the sound produced by the membrane.
• Number of Modes: number of modes used to simulate the object. As the number of modes
is increased, the number of partials in the sound increases but also inevitably the calculation
load.
• Excitation point-x: x-coordinate, in meters, of impact point from the lower left corner of the
membrane.