Is the css setting speak:none now equivalent to aria-hidden="true"?

There does not seem to be reliable data on support to speak, but it seems to be unimplemented.

Independently of the implementation status, speak: none is not equivalent to aria-hidden="true".

According to the CSS Speech Module CR, the speak property “determines whether or not to render text aurally”, i.e. audibly.

According to the ARIA specification, aria-hidden “indicates that the element and all of its descendants are not visible or perceivable to any user as implemented by the author” (italic in the original).

Thus, aria-hidden="true" does not cause anything; it just declares that the author has hidden the element. And it relates to all kinds of rendering: audible, visible, tactile, or whatever modalities might be invented in the future.