Playing the same IPA pronunciations using AVSpeechSynthesisIPANotationAttribute on iOS 26.5 and iOS 27.0 beta 1 yield very different results. It appears as if iOS is ignoring the IPA symbols.
FB23041286
Sample app is here: https://github.com/ryanlintott/SpeechSynthesisIPAExample
Thanks for the post and submitting the bug, it seems like is a known issue. Please give the team time to get back to you with their comments.
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Albert WWDR
