I have some problems with the sound in Oblivion. Lately, every sound effect, music and voice effect fade when I walk or move the camera. It's only barely hearable and sometimes when a sound effect plays, the music stops and vice versa, could someone help me with this problem?

This may be the most common problem with your computer just barely meeting the the system requirements for a game like Oblivion.
I recently moved all the music files that Ob uses, from my Data folder, to hopefully gain more frames per second. It works better than I hoped, but I already miss the "City theme" music
If you use Quicktime, you can play the mp4 sound files before you remove them, just to make sure, but wouldn't entirely delete them. Locate these files under "Oblivion\Data\Music"

Thank you for the help but I managed to fix it. Since my pc exceeded the recommended requirements, I went to search in my pc for the problem. First of all I forgot to reset my sound systems to stereo since I removed my 7.1 surround system, and second my sound card was completely covered in dust...