Avoid using documents that have been scanned if at all possible.
A scanned document is actually one large image per page and a screen reader will see this as a blank page. Scanned documents are not accessible to screen readers without additional work that is often extensive. Instead of printing out and scanning a document and trying to create a PDF with it, it’s best to create a PDF directly from a source electronic document (like a Microsoft Word or Microsoft XL file).
To test if the document needs Optical Character Recognition (OCR):
Select a position using the Select Tool and try entering a letter. If it is a scanned document text can not be added or edited.
If a scanned document is the only option available, Text Recognition (also known as OCR) will need to be applied to the file before the document can be remediated for accessibility.
Menu: Tools > Create & Edit > Enhanced Scans > Recognize Text
Depending on files size this process can take some time.