Along with its announcement of the Pixel 4a, Google just announced Live Captions for video and voice calls. The Live Caption tool turns audio into onscreen subtitles in real-time, but was limited to social media, voice memos, and videos before today.
According to Google, Live Captions are processed locally and never recorded. The person on the other end of a call hears an audio announcement when Voice Captions are active, nothing is stopping callers from screenshotting transcribed conversations on their phone.
The Live Caption tool is available on all models of the Pixel phone beyond the Pixel 2. To activate Live Captions, enter your device “Settings,” tap “Sound,” and open the “Live Caption” options. Once Live Captions is enabled on your device, you can flip it on and off from your Volume Controls—the little window that pops up when you turn your volume up and down.
Live Captions are only available in English. Third-party phones that support Live Captions, such as the Samsung Galaxy S20, cannot use Live Captions for video or voice calls.
Source: Google via Android Police