Good questions and they have been asked quite a few times here in this forum and elsewhere.
You do NOT try to chants the sounds out loud. If not using the CD, you try and imagine the sounds in your mind (or a better description would be try to imagine the sound in the part of the body where you have moved the energy!
). Just imagine the "Om" or the "Muah" in Master Lin's voice resonating with the energy ball that you are moving around the Small Universe.
Hope that helps.