Hello @jakub chudiak , Thanks for using Microsoft Q&A Platform.
I don't think it works using that custom voice as parameter in the SSML. To use your Custom voice, you can use these features like Custom neural voice (CNV), Custom neural voice (CNV) Lite and personal voice for text to speech.
Custom neural voice (CNV) is a text to speech feature that lets you create a one-of-a-kind, customized, synthetic voice for your applications.
However, Custom neural voice access is limited based on eligibility and usage criteria. Request access on the intake form.
Access to Custom neural voice (CNV) Lite is available for anyone to demo and evaluate CNV before investing in professional recordings to create a higher-quality voice.
I hope this helps.
Regards,
Vasavi
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