Have you tried using TextAloud in 'single article' mode? From the TextAloud main window, click Tools -> TextAloud Options, and click the Article Options panel. Near the bottom of the panel, you'll see a checkbox labeled "Limit Number of Articles Loaded to 1 (Single Article Mode)". When this option is selected, TextAloud will keep only one article in the display, deleting the current article as the next one is loaded.
Does that do what you're looking for?