Lowering Volume on Audio Source mutes different Audio Source (on other Object) happens on Vive with Headset

Hey there, i was lowering Volume on Audio Source with a script. Only on Headset it mutes the Audio Source on a different Object.

I tried thison Vive with Headset.

I tried different Audio Mixers for both Audio sources. I get a Signal (it did not even change) and the volume did not change as well. It's muting though.

Just on Reverb i hear it all the time.

Any idea what's causing it?