Volgens Google: (je grootste vriend!)
It is useful to reset the sound card or force it into a certain mode before playing MIDI files, otherwise certain MIDI devices can react unexpectedly by playing wrong sounds (e.g. drums play piano sound).
The standard sysex commands will work only if your sound device supports GM, GM2, GS or XG compatible modes.
Read about supported MIDI commands in MIDI implementation chart of your keyboard manual.
offtopic: Waar woon je precies in zeeuws vlaanderen??