powerpoint presentation help

hello, I have prepared a powerpoint presentation for a patent. Everything is fine, except for the background music and voice recordings that cannot be heard during the presentation although I added them and tested them on my computer. All people I've sent the presentation to tell me they don't hear the voice, or the music. I need: 1. to play the voice recordings on a medium sound level. 2. to play a background music on a low sound level on the background. the song is Be Patient (Still) - Smidi, and I need it to play during the whole presentation, to loop if necessary, and to play across all slides. the voice recording files have the same slide number to which they belong. the song file has to be downloaded and added. that's the project.