Play Soundfile while pause timeline

Hi,

I want to setup a software training. Every time the learner have to click on the correct button "in the software" (a video) a colored rectangle appears, which stops the video. While the pause I want to play a sound file (speaking instruction what the user can find here and that he/she have to click on the button to move on). Over the rectangle are 2 triggers, one to pause the timeline and one to continue the timeline after a click on the rectangle.

But now the question: How can I play the sound while the timeline pause? I tried it with layers, integrate the sound file and set a trigger to start the layer after the rectangle appears. But the trigger to pause the timeline prevents this.

Any ideas?