I made a quick demonstration of the new features.  I think it is important to watch them to get an idea of how it works before you upgrade:

https://www.youtube.com/watch?v=1StXyf-4SmA

installing the beta now worked for me, but "silence threshold" doesn't appear in my settings...  

p.s. using android 4.2.2 on my Galaxy Nexus

OOps. I guess you are using German?  If you can switch to english temporarily you should be able to adjust it and then hopefully it will still work when you switch back.

Thanks for letting me know!  Glad this is just a beta release

Yes, you're right. Switching to English helped and it still works after switching back to German.