Following are a few excerpts:
The name screen reader is a misnomer since they do not read the screen. Screen readers load the page content from the browserÃ¢â‚¬â„¢s document object model (DOM) into a virtual buffer. The user is then able to review this virtual buffer at will, using numerous hotkeys. Items such as links, form fields, and some other elements are identified when they are read. When the user finds a link or other clickable element that they wish to activate, they simply press Enter, and the screen reader tells the browser where they Ã¢â‚¬Å“clickedÃ¢â‚¬Â.
In Jaws, this event [the scroll event] is fired at seemingly random times, including sometimes on page load.
In Window Eyes, on the other hand, it fires at much more logical timesÃ¢â‚¬â€after the user has read several lines of text. However, keep in mind that all scrolling, as such, is taken care of by the screen reader. From the userÃ¢â‚¬â„¢s perspective, there is no such thing as below the fold, as everything on the page is all in one big buffer, and screen readers give no indication to the user when they scroll the screen.