Why does tv sound go off when switching off the ceiling fans with pull chain?
You're on the right track. Generally when you have what seems to be unrelated electrical problems it's usually one of three things. First and most common is you have a broke neutral. Second somewhere in your system you have a phase loss. Third and most difficult to find is the system has had a previous problem and someone has tried to fix it by illegally tying neutrals and ground together in the system and now it's a mess. 

Since you are saying it is happening full house, my educated guess would be that it is ahead of the panel (between the panel and the utility connection).

First I would look for a broke neutral. If you have an overhead drop carefully exam to make sure the bare wire (the neutral) is not broken or loose on the drop. Alos look for cracks in the insulation of the drop. If you find a break you can call the utility company and they will make the repair. If it's anything after the meter you have to make the repair. Make sure all of your connections in the panel and meter are mechanically and electrical sound. If you have a meter check for a good voltage reading between the phase conductors and neutral bus. Check the voltages on all breakers including the main both in the on and off positions. If there are any voltages that are not around 120V or 240V, make note of them and look for your problem there. 

If you can't find a broken neutral visually and you don't have an extensive electrical background. I would recommend you find a highly skilled electrical serviceman to help locate your problem since it takes quite a bit of testing and maybe just some dumb luck to locate your problem, and some of the testing may require circuits to be active. Also if you want to examine the meter you may have to break the utility seal and that might require a permit by an electrical contractor.

Hope this helps, good luck and stay safe.