Add Without Background Sounds

[gautierchomel]

ONIX 175 A312 Without background sounds

Currently not in crosswalk and not in schema.org but a WCAG requirement?

Originally posted by @chrisONIX in w3c/publ-a11y#315 (comment)

[mattgarrish]

Sorry, this issue is unclear to me. I don't believe there's an SC that prohibits background sounds.

The referenced onix value is adjacent to the ones for sound effects and background music, so it doesn't sound like it's related to SC 1.4.7 which is about audio content that is primarily speech having low or no background noise (that seems like it's covered by code 196-27).

SC 1.4.2 requires that if audio automatically starts and plays for more than 3s there must be a way to disable it, but that again is not the same as no background music at all.

If this is about books not having "mood music" automatically playing in the background, will adding a feature really help users? Won't this be true for the vast majority of books and web sites? It sounds rather like something you'd want to warn people about in the summary when it's present.