/ Application of Wave Field Synthesis in the composition of electronic music
The program can also calculate room reflections, when a room is defined by the user through the position of four walls of a rectangular room, an absorption factor and the order of calculation. The calculations are done with the mirror image source model (see also Berkhout 1988). Though with WFS one can in principle also create virtual sources in front of the loudspeaker array, this was not yet implemented in the current version. It will however be implemented in a future version. 4.1 Sound source definition The user can define various sources, each with their own characteristics. A source in this context is the virtual source from which sound emanates in space, whose spatial parameters can be given by the user. For each source, the user can set the type of source (a point source having a specific location or a plane wave having only a direction), whether it is moving or stationary, its location or angle, the sound input channel at which the sound will be supplied and in the case of a point source, whether reflections have to be calculated or not. If reflections have to be calculated, room characteristics can be defined (these can be different for each source). In the case of a moving source, one can define a path through space and choose to let the movement loop along the path. In figure 3 a screenshot of the source and path definition dialog is given. After supplying all information and storing it, the user can get two overviews: a general overview in a list, with some of the most important parameters for each source, and a graphical overview showing the paths of the sources through space (figure 4); one can indicate of which sources the path is shown. It is also possible to play a movie to get an impression of the movement in realtime. For the movement of the sounds, one can set the number of breakpoints along the path and a fade order. A breakpoint is an intermediary point on a path; movement is created by switching from one breakpoint to another. By using a fade between succesive breakpoints, the movement can become smoother and possible clicks in playback can become softer. The user can choose to let the amount of breakpoints on each segment be calculated automatically. In that case, the program uses a total of 40 breakpoints per source and divides these over the segments of the path, depending on the length of the segment and of the path and on the time interval. Figure 4. Screenshot of the graphical overview of the source path. The numbers at the points between segments indicate the departure (dark) and arrival (light) times. The dots in between the path and the reference point are indicating the loudspeaker array.
Top of page Top of page