If you mean alter by mixing different media files then you can take the following code. Second sond file will play only if your device support mixing. First file is the main sound file. Second one is usually a small duration sound effect file.
Player musicPl = Manager.createPlayer("file:///SDCard/BlackBerry/Music/musicfile.mp3");
Player soundPl = Manager.createPlayer("file:///SDCard/BlackBerry/Music/soundfile.amr");
musicPl.realize();
soundPl.realize();
musicPl.start();
if (System.getProperty("supports.mixing").equals("true"))
{
for (int i = 0; i < 10; ++i)
{
soundPl.start();
Thread.sleep(500);
soundPl.stop();
}
}
NOTE:- Above sample will not alter any file. Just mix multiple sound file.