Pronunciation

Speech synthesis guesses. Given lead it has to decide between the metal and the verb, given SQL between three letters and a word, given 2-4 between a range and a subtraction, and given your product name between whatever pieces of English it can find inside it. Most of the time the guess is right and nobody notices. When it is wrong the sentence stops making sense, and the reader has no way to tell whether the interface said something strange or the voice did.

WCAG 3.1.6 Pronunciation sits at level AAA and asks for a mechanism when meaning is ambiguous without the pronunciation. What it does not do is hand you an attribute, because the web platform never shipped one. CSS Speech defined speak-as and no screen reader implements it; SSML is available inside spoken media, not inside HTML. So the techniques in practice are all workarounds: write the reading out in visible text beside the word, mark the word aria-hidden="true" and put a respelling next to it in visually hidden text, or use ruby for the languages that have a real annotation convention for this. The respelling trick is the one authors reach for most, and it is worth knowing that it costs you the visible word in the accessibility tree, so it should be used on a name or two and not on prose.

Two neighbouring terms carry more of this load than people expect. Getting the language attribute right is the single highest-value pronunciation fix available, because it chooses the voice: a French name inside an English page is read by an English voice until lang="fr" says otherwise, and no amount of respelling will beat simply telling the reader which language it is in. An abbreviation marked up properly does not change pronunciation on its own, but writing out the expansion gives the reader a form the voice can say, which is often the real reason the shortening was unreadable.

Test with a real voice before writing any of it. Most pronunciation bugs are in three places: proper nouns, units and quantities, and strings people read as letters when the voice reads them as words. Fix those and leave the rest of the page alone, because every hint you author is a piece of markup that lies to a search engine, to a copy-and-paste, and to the next person who edits the sentence.