You really need to ask yourself what your interests are and find a fit there. That way it will be fun and interesting and not just boring work. I think I built Dolby for my stereo but that was 35 years ago.
Lots of results, though most are people looking for their FYP. You may get hints from their results. Mike's idea was great, but you sounded uninterested. Maybe you can limit the possibilities to what you might accept by telling us a little about what aspects of
BTW: somebody did patent a "lost remot control finder" which was to install a beeper in the remote that would yelp when you pressed a button on the TV to find the remote. Cool idea, never caught on.