Read PDFs Aloud: Tagging

Image of a PDF logo and a person putting on headphones.
Images used with permission from
I have talked about making PDFs accessible on this blog before. In addition to being able to search through the text, another of the benefits of running OCR (optical character recognition) on a PDF is that it makes it possible for a person to have the document read aloud or to listen to the document with TTS or text-to-speech technology.

Most of the time the OCR process works without issue. Sometimes however, the OCR will finish and the document says "blank" when it is read aloud. How do you know that a document will be able to be read aloud? I will outline below a few steps you can take to make sure that your PDF will be ready to be read aloud.

Checking Your PDF

So how do you know if your PDF can be read aloud? The following steps will illustrate how to do so in Adobe Acrobat Pro. The first check is to make sure that the document has been OCRed. To check this, you can open the PDF and then click and drag to select the text. If this is successful then this means that the document has been OCRed (has rendered text). The next step is to attempt to listen to the document.  You must enable "Read Out Loud." To do so click View > Read Out Loud... > Activate Read Out Loud. You can then try reading a page (commands below). If the the document reads correctly you are good to go. If you hear the word, "Blank," then you will have to fix the document.

Steps To Fix Your PDF

If the document says "blank" when it is read aloud the most likely cause of this is that the tags within the document are corrupt or otherwise incorrect. The way to fix this is to delete and recreate the tags.

To do so:
1. Click View > Show/Hide > Navigation Panes > Tags.
2. Right-click or control-click (Mac) on the Tag root and select Delete Tag. this will remove all of the current tags.
Screenshot of right-clicking the Tag root in adobe Acrobat Pro.

3. Right-click or control-click (Mac) again and select, Add Tags to Document.
Screenshot of right-click on Tag root and selecting "Add tags."

Acrobat will go through the document and create tags. Once it is complete you will see a report of the action it took located in the Tags pane. You can now try having acrobat read the document aloud.

These steps were based on the forum post here.

Read a PDF Aloud

There are benefits to being able to have a document read aloud: better comprehension by being able to read and listen at the same time, time saving, and the ability to plan for reading. If a person can listen to a document they can listen at their convenience. With the apps listed below it is also possible to customize the speed of the speech. With practice it is possible to listen much faster than normal speech. This can save time. For some students who are not native English speakers, being able to listen to the document being read aloud may help them better comprehend the material. 

Adobe Reader/Acrobat

To enable Reader/Acrobat to read a document aloud you can do the following:
Click View > Read Out Loud... > Activate Read Out Loud

Once Read Out Loud is activated the keyboard shortcuts for controlling the read aloud in Reader/Acrobat are:
Activate/Deactivate    Ctrl/Cmd + Shift + Y
Read This Page only    Ctrl/Cmd + Shift + V
Read to the End of the Document    Ctrl/Cmd + Shift + B
Pause                             Ctrl/Cmd + Shift + C
Stop                               Ctrl/Cmd + Shift + E

Used in combination with the annotation and commenting tools in Acrobat and Reader, the option to read a PDF aloud is a powerful learning tool.

Apps for Reading PDFs Aloud

One way to take this capability further is to go mobile. Doing so removes the confines of time and space, freeing the reader to to so when is convenient for them. There are two free apps that I have found that are good for this purpose: @Voice for Android and Natural Reader for iOS.

Both apps have the following functions:
  • connect to Google Drive to open a document
  • book mark phrases as they are read
  • highlight the text being read as it is read
  • adjust the speed of the speech
Natural Reader does offer a web tool and downloadable application (free or paid - Mac/Win).


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