After joining the iOS 17 beta programs this last June, I noticed that the voice I was using for Voice over had changed. Although it was technically the same voice, the file size of the voice was a tenth or less of what it was before, and with that size deflation also came a rather drastic change in the quality of the voice. It had gone from clear and easily understandable to sounding like a drunk; cutting off bits of words and slurring at higher rates of speech.
This was unacceptable. Browsing through social media with this voice was an awful experience, and so rather than stick with that voice I switched to another... Until today.
How to get the better Siri voice back
Although this is a rather strange workaround, I've found it to work as of the day I'm writing this tutorial.
From your iPhone's home screen, open the settings app and head to Accessibility settings. Once you're there, click on Voice over and scroll down until you hear the word "Activities." Scroll through the list of activities that already exist (The only one for me was "Programming") and click on "Add Activity."
Activities in Voice over are like profiles for different situations. So, for example, if I like listening to one voice with punctuation level set to Some while scrolling through Twitter, but I'd prefer another voice while doing my general phone browsing with punctuation level set to all and Emoji announcements disabled, I could add an activity, give it a label, and quickly use the rotor to switch modes.
We're going to create an activity that will be used for all situations. If you already use activities, and would like to set this voice for more than one, it should work.
Give your activity a name, and select the voice. Set it to Siri or whatever voice you prefer, and save the activity.
Now, go to rotor settings, which should be the item in Voice over settings just before Activities, and scroll down to and click "Rotor items." Scroll down to "Activities, and select it if it is not already selected. Go back to Voice over settings, then feel free to close out of the app.
Use the Rotor, activated by taking two fingers on the screen and rotating them as if you are spinning a dial, and listen for the word "Activities." Once you hear it, swipe up or down until you hear the activity you created. The name of the activity should be spoken by your chosen voice.
Hope this was helpful!