Hear transcription is English-only. These flags apply on sync (
POST /v1/audio/transcriptions), streaming (GET /v1/audio/transcriptions/stream), and async jobs (POST /v1/transcription/jobs).Flags
numerals is independent of the others. dictation, drop_fillers, and vocabulary are not implied by smart_format.
smart_format
Opt-in. Changes case and punctuation only. Word identity is guarded; if wrapping would add or drop a word, Hear returns the unformatted final.
and. Run-on splits are conservative: they fire only with enough words before a new clause (the meeting/call/order/…, also / anyway / meanwhile, please send/call/…, or a late standalone i). Tag questions use a short closer (right, yeah, okay, isn't it, …).
smart_format does not:
- Invent emails, URLs, or street addresses
- Expand or rewrite words (
threepmstaysthreepmunless ITN already normalized it) - Remove fillers (that is
drop_fillers) - Honor spoken “period” / “comma” (that is
dictation) - Format non-English text
dictation
Separate from smart_format. Off by default. On English finals only, these spoken commands become punctuation:
period→.comma→,question mark→?new paragraph→ a paragraph break
smart_format on as well if you also want sentence capitalization.
drop_fillers
Off by default. Strips filled pauses (um, uh, umm, uhh, er) on English finals. Do not enable on legal or compliance audio by default — those tokens can be evidence.
vocabulary
A per-call phrase list, not a stored project glossary. Max 32 phrases, 64 characters each. Matching is case-insensitive and exact; the transcript is re-cased to the form you sent, and the same list is boosted for this request only.
Phone numbers
NANP grouping lives undernumerals / ITN, not smart_format:
Surfaces
Examples
partial greyed and only commit speech_final / final. That is how you get live captions that snap to punctuated text instead of flickering punctuation on every hypothesis. See Stream speech-to-text.
Failure behavior
Formatting is best-effort and fail-open. A timeout, exception, or lexical-guard miss returns the previous final unchanged.dictation and drop_fillers may change word count; when word timestamps cannot be realigned, the transcript still updates and the words array is cleared. Clients should not treat missing punctuation as an API error.
Next steps
Stream speech-to-text
Partials vs finals, commit, and endpointing.
Conversation intelligence
Batch jobs, diarization, and post-call analytics.