Here are a few suggestions that don’t require conversion of PDF to another file format. One caveat is the PDF must be accessible. A scanned or inaccessible copy will not work with text-to-speech programs. Images could be problematic as some TTS programs won’t read alt text. 

1. Adobe Read Out Loud (Built into Adobe Reader, reflow) 

2. Balabolka (Freeware – synchronous highlighting) 

3. Natural  Reader (Free and paid versions, will convert to MP3) 

4. Read&Write (Software and Chrome extension, free and paid versions, dual synchronous highlighting, converts to MP3) 

5. Foxit PDF Reader (Free download, annotates)  

6. Voice Dream Reader  (Paid  and free app, iOS, Android, synchronous highlighting) 

7. KAMI (Paid version has TTS,  annotating, highlighting)  

8. ZoomText (Paid software for low vision, TTS, magnifies text, variety of color enhancements)