For WAV, the sample rate and channel count are read from the file header. For raw PCM, pass
sample_rate and channels in the config part — see Sending raw PCM audio.
Audio that violates a constraint is rejected with a 400, 413, or 415 — see Error handling for the full error table.
For audio longer than 120 seconds, use Pre-recorded STT. For live audio, use Real-time STT.