Why is my galaxy s7 edge making a weird sound?

Some possible issues and fixes for you.

1. Do a software update, this is found under General settings normally.

2. Update YouTube app and Netflix. Try a different app that would normally always have perfect sound.,Example: Pandora

3. The speakers may be going out on your phone. This would require the back glass to be removed and the speakers replaced. If I am right this will either be next to your Charge port on a flex.

Hello,

If this happens on different apps like Netflix and YouTube as you said, it must come either from the software, in this case veryfying if there is a new update and if not resetting the phone completely could solve the problem, or it comes from the speaker, then you will have to change it.