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

1.2.6 Sign Language (Prerecorded)

Conformance level: AAA
Criterion released in WCAG version: 2.0

Official description of the success criterion

Sign language interpretation is provided for all prerecorded audio content in synchronized media.

What to do?

Provide sign language interpretation for all prerecorded audio content.

Why is it important?

Makes audio content accessible to people who use sign language as their primary language.

More about this criterion elsewhere