Sound problems with the X-Box 360?

Hay,

I have the following problem: If I want to watch Netflix or YouTube via the X-Box 360, the sound itself works. You can hear music and background noises - but as soon as someone starts talking, you can't hear it or only hear it very quietly.

This also happens when I listen to headphones. So it's not the TV.

I've already tried a few things like restarting, resetting, checking the cables, etc.

Maybe someone knows this problem and can help me there.

It can attach to the hdmi cable or stop at the tv otherwise look at Microsoft online support