Question: Please answer these questions on closed captioning. Why are so many words misspelled or left out entirely? Instead of letters, why are there sometimes black boxes? Why does the close captioning not always match the words being spoken? Don't get me wrong; it is a wonderful device for those of us who are deaf, hard of hearing, unable to understand what is being said or who just need to mute the sound at times. But if closed captioning is not done accurately, what's the point? — Chris, Dayton, Ohio
Televisionary: The answers to all those questions, as is often the case with technical questions I get, aren't so simple, Chris. But I'll do the best I can.
Basically, it depends on what kind of TV or external decoder you're using (and how old it is), the quality of your reception, which captioning house is handling the captioning for your show, and whether the program you're watching is live or not.
Addressing your questions in order: There could be a number of different reasons why words are misspelled or left out entirely. If you're watching a live event, for example, you could see a typo by the person keying in what's being said. Sometimes that means a misspelling and sometimes it means that the captioner, who uses a steno system allowing for an entire word or phrase to be entered at once, can make big mistakes with one false move.
If there's a problem on the transmission end or some interference in your reception, your decoder may not be getting all the available information, which means it drops characters or substitutes white or black squares for what it interprets as bad data. There are also a number of reasons why the captioning may not match what's being said. On children's shows, for example, the captioning company may simplify things in order to make it easier for kids to read. Or maybe the captioner worked from a script that's since been changed — maybe by a person who ad-libbed some of what was said. Other times, the video has been edited since the captioner received their version.
Now, giving credit where credit is due, I checked my understanding of the system against a FAQ put together by captioning guru Gary Robson. For a more in-depth take, stop by his site.