By the Numbers: NIH Quick Statistics About Hearing(link is external)
Best Practice: Demonstrate workflow for converting to 3D compatible caption file formats and making 3D caption placements.
Example: Adding Closed Captions to 360 Video with Adobe Captivate(link is external)
Further Reading: BBC's User Testing Subtitles for 360° Content by Andy Brown, ImAc Consortium's 360 Content Accessibility(link is external) site