The implementation for these should be in the .cpp file.

The more I look at this, the more I'm going to suggest dropping JankyTask and implementing the logic here.  The logic really isn't hard, and the extra layer of abstraction doesn't really fit very well in this application.  You want to start a thread on StartListening (locking it out so you can't call it more than once) and signal the thread to stop in StopListening (and lock it out there as well so it can't be stopped multiple times.  Pretty simple.