random really loud music in half life 2

[COBWEBB]

so I was playing through half life 2 cause i hadnt played for years. im on the part in sand trap where you defend the light house from drop ships right before the escape tunnel. i reloaded my game save and everthing was normal until out of nowhere loud techno music starts playing in the background and im pretty sure it wasn't from half life. I tried to get in game again so I could record it, but it only happend the one time any clues as to what happend? i didnt have a web browser of any kind open. steam was open on the library tab, no videos or audio there either and i havent modded the game in any way.

[Falro the Great]

I know at least HL1 plays music from any CD in your CD drive. Likely that's why.

[COBWEBB]

There's nothing in my cd drive.