When I tell people that I use software on my computer that reads text out loud, perhaps that comes across as abstract information. When a sighted person looks at the screen, it is very busy and the person chooses what information to focus on. Most of this choice-making is subconscious but also deliberate. The eyes take in a lot of information quickly, and I understand that it is hard for a sighted person to understand how a blind person can operate in the same environment in a different manner and make the same choices.
My software does a lot of this work for me. For instance, it focuses attention on the window where my cursor is located and will not read things outside this window unless I give it a command to move to another window. In this way, some of the “screen clutter” is already filtered away from me. If I need to know what other windows are open, I have the ability to check; but this is not something I need to know at all times. If you think about it, you are not constantly looking at all of your windows. In fact, you may even minimize them so that they don’t get in your way.
Screen reading software is complex software that includes features that allow it to recognize when certain things are very important and need to be read immediately (e.g. the highlighted field where the cursor is located when I am installing a new piece of software). Some of this choice-making ability is enhanced or limited by things that software developers do. This ia why people who are blind become very aggravated about accessibility.
If allowed, a screen reader program will read out the entire contents of a window. This can be quite overwhelming. It would be to you as well–after all, do you pay attention to all of the information on a web page, or do you look for specific types of items? Chances are that you are looking for something specific, or at least some type of information. For example, when you visit Facebook, you might be looking for the place to post your status update, and you know exactly where it is. You also probably know where not to look if you want to avoid the ads.
Fortunately, I am not stuck listening to the entire web page until it is finished reading! Screen-reading software includes features that allow me to tell it to look for things, like the field to post my Facebook status. I can also tell it to read certain portions of the screen (for example, the title bar, the status bar at the bottom of the screen, etc.) I can choose to have the letters spoken as I type them, or to have words spoken after I press the spacebar, or to have no input while I type. There are numerous ways that I can tell the screen reading software how to give me information about what is on my screen.
A note about braille displays is important here. Screen reading software and braille displays work hand in hand. It is not possible to run a braille display with a computer without running screen reading software. The screen reading software feeds information to the braille display and also tells it how I want that information displayed. “Translation” of print characters to braille, including (if necessary) the appropriate characters that represent another language in braille, is all handled by the screen reader. Please understand that braille itself is not a language. It is a writing system that can represent any language; but the rules for use of dot patterns in the writing system in any given language are not stored in the average computer–unless it is a Mac running a newer OS.
Several screen reading software packages exist, and some are even free. The choice of which package to use is something a person makes based somewhat on preference and somewhat on the features included and the way the software interacts with the programs the person needs to use. I use advanced features of Microsoft Office and need Hebrew support. I also need to be able to add characters to the braille table since I study ancient languages. This means that some of the software packages were not the best options for me. I continue to follow the development of Greek and Hebrew support in the Mac and IPhone, which shows promise.
If you have questions about how sccreen readers work, please post them in the comments.