Computer Configuration > Administrative Templates > Microsoft Edge
Both
HKLM\Software\Policies\Microsoft\Edge
Set whether the browser can leverage Online Text to Speech voice fonts, part of Azure Cognitive Services. These voice fonts are higher quality than the pre-installed system voice fonts. If you enable or don't configure this policy, web-based applications that use the SpeechSynthesis API can use Online Text to Speech voice fonts. If you disable this policy, the voice fonts aren't available. Read more about this feature here: SpeechSynthesis API: https://go.microsoft.com/fwlink/?linkid=2110038 Cognitive Services: https://go.microsoft.com/fwlink/?linkid=2110141