PlaySource tellPreparations() {
      if (parameters.getPreparationTexts().length == 0)
         return PlaySource.speechSynthesis("");

      List<PlaySource> playSourceList = new ArrayList<PlaySource>();
      for (int i = 0; i < parameters.getPreparationTexts().length; i++) {
         playSourceList.add(urls(String.format("%sprep.wav", PREP_PATH)));
         playSourceList.add(urls(String.format("%s%s-start.wav", PREP_PATH, parameters.getPreparationTexts()[i])));
         playSourceList.add(urls(String.format("%s%s.wav", PREP_PATH, parameters.getPreparationTexts()[i])));
      }
      PlaySource[] playSources = playSourceList.toArray(new PlaySource[0]);

      return PlaySource.sequence(playSources);
   }