Apple does not officially allow users to roll back iOS versions to previous releases, meaning you cannot revert Siri’s voice to the older version if an iOS update changed it. However, users can change Siri’s voice to different options available within the iOS settings. These options include various accents, genders, and languages, so you can choose a voice that suits your preference even though you can’t roll back to the older Siri voice directly.
To change Siri’s voice: Go to Settings > Siri or Settings > Apple Intelligence & Siri. Tap Language to changethe language Siri uses for requests and responses. –> Change Siri voice or language
You won’t be able to return to a previous version of Siri’s voice if an update has changed it, but you can try other available voices to find one that you like.
