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I see a similar behavior with these voices when I use them through speech studio. Using the words "hi" and "fine" produces different results with these voices, while using them in a sentence seems to generate the required output.
I have seen similar behavior with other voices in the past and using the words in a sentence is the workaround that worked for most users.
I request you to raise a support case through Azure portal or by providing feedback through the feedback option in the studio, so that our support team can look into this issue internally and check if they could verify the pronunciation for these words with these voices and make changes, if necessary, in the future iterations.
Hope this helps. Thanks!!
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