A11ying with Sanna - Web Content Accessibility Guidelines a guide to the accessibility requirements
1 Perceivable

1.2.4 Captions (Live)

Conformance level: AA
Criterion released in WCAG version: 2.0

Official description of the success criterion

Captions are provided for all live audio content in synchronized media. 

What to do?

Provide captions for all live audio content in synchronized media.

Why is it important?

Ensures live audio content is accessible to people who are deaf or hard of hearing.

More about this criterion elsewhere