With the fifth beta of iOS 27, Apple has expanded the voice customization options for Siri AI. Pace and Expressivity can now be adjusted for more of the available voice options instead of just the two American voices. Pace changes talking speed, while expressivity changes emphasis. ‌Siri‌ AI voice customization is done on-device, so the feature is limited to newer iPhones. You need an iPhone 17 Pro, ‌iPhone 17 Pro‌ Max, or iPhone Air to use voice customization on an iPhone.