Lex Luthor explain that there is a bug in the installer for the new map for the Medal of Honor demo.. (thanks Blues) Here is a snap how to fix it:

I've discovered a little bug in the new released demomap "the hunt" which can be fixed easily. During the Installation the background sounds are installed at the wrong folder and that's why you don't hear any backgroundsounds in the new map. To fix this just extract the "Amb_M5_TownExt_2.mp3" file to the following place : "medalofhonorfoldermainsoundamb_stereo".. That should fix it all.