Microphone only. One-way: use headphones — translation plays continuously. Two-way: mic pauses while TTS plays.
One-way: Use headphones so the mic does not pick up the speaker; you will hear translation continuously without interruption. Two-way: Mic is muted while TTS plays to avoid feedback.
On mobile: use Chrome or Safari, allow microphone, keep the screen on. One-way: use headphones for continuous translation. Two-way: mic mutes during TTS. Add to Home Screen (browser menu) for an app icon.