This is a term referring to use of a computer software package, a sound card and speakers to create speech as a substitute for a computer monitor for blind people. In simplest terms, the software analyzes the data in the video buffer of the computer and turns what it sees into phonic components. Typically, the software has a dictionary of many words with their preferred pronunciation against which to compare the data. The user can control the portion of the screen to be reviewed, the amount of punctuation to be read, among many other features. When commanded to do so, the software sends the data to the sound card and the data is voiced.
Special sound cards and external devices are also used to free up the internal sound card for other purposes.