Optional: more reliable translation with a free Microsoft key
Google's free endpoint can block heavy use. A free Azure Translator key (F0 tier, 2 million characters a month, roughly 40 lectures) is used first when added. It is stored only on this device.
Speech is recognised by Safari (Apple dictation) and translated by Google Translate (or Microsoft, if you add a key), so audio goes to Apple and text to Google or Microsoft. The transcript is stored only in this browser.
Live Mandarin captions for English lectures
Sit near the lecturer and tap Start. Allow the microphone.
A Chinese draft appears at the bottom while the lecturer is speaking. Each finished sentence moves up with its English.
Keep this page open and the screen on during class.
After class, open Settings to save or copy the transcript.