Originally Posted by sirbruce
There's nothing in the manual to indicate that Text-to-Speech would *not* work on a text PDF, so there's no reason to believe it wouldn't.
Much of the manual seems to be a cut and paste from the Kindle 2 manual, with some mis-statements about PDF support.
A reason for thinking that text to speech might not work for PDFs is that getting the text in the right order for speech is essentially the "reflow" problem (although images and most formatting can be ignored). We already know that reflow can work much of the time, and is included in Adobe Digital Editions that Amazon has licensed for the DX. This might be good enough, given that read aloud is "experimental", but my guess is that Amazon has not implemented even this special case of reflow for PDFs.
Having said how hard, in general, PDFs are to read aloud, I need to add that Adobe Reader (for Desktops) has a read aloud option but with four reading modes based on the type of PDF.