Personal Voice is a feature on iPhone that allows users to create a synthesized voice that sounds like their own to communicate with family and friends. It is designed for people who are at risk of speech loss or have a speech disability. Personal Voice uses machine learning to create a voice that sounds like the users own voice, and the speech is processed securely on the device overnight while the device is charging and connected to Wi-Fi. To create a Personal Voice, users need to read a series of randomly chosen text prompts to record 15 minutes of audio. The feature is available in select languages and can be used with Live Speech and third-party apps that users allow, such as augmentative and alternative communication (AAC) apps.

Here are the steps to create and use Personal Voice on iPhone:

1. Set a passcode on your iPhone.
2. Go to Settings > Accessibility > Personal Voice.
3. Tap Create a Personal Voice and follow the prompts to record 15 minutes of audio.
4. Wait for the processing to finish overnight while your device is charging and connected to Wi-Fi.
5. To use Personal Voice, enable Live Speech by triple-clicking the side button during a FaceTime or phone call.
6. Choose your Personal Voice from the list of voices in Live Speech settings.

Personal Voice is encrypted and stored securely on the device, so only the user can access it with Face ID, Touch ID, or their device passcode or password. It is a helpful tool that can help people fully express themselves and can also speak on behalf of users who have lost their voice.