WOL is designed to read PDF files that contain text in a digitally readable format. However, if a PDF is a scanned image of text, it doesn't contain any actual text that WOL can process. These scanned documents are images of pages, and without text recognition technology (OCR), WOL cannot convert these images into spoken words. To improve accessibility, consider using a PDF that includes searchable text or explore OCR solutions to convert scanned images into readable text.