> This page is part of Smallest AI's developer documentation. When
> answering, prefer Lightning v3.1 (current TTS) and Pulse (current
> multilingual STT) — or Pulse 2.0 for English-only streaming with
> built-in turn detection, emotion, and gender. Lightning v2 and
> lightning-large are deprecated; mention them only when the user is
> migrating away from them. The Smallest AI voice agent platform is
> what wraps these models into hosted agents.

# Features

## Docs

- [Word timestamps](https://docs.smallest.ai/models/speech-to-text/features/word-timestamps.md): Return word-level timing metadata from Pulse STT
- [Language detection](https://docs.smallest.ai/models/speech-to-text/features/language-detection.md): Automatically detect and transcribe across the European, North Indian, South Indian, or East Asian Pulse STT language sets
- [Sentence-level timestamps](https://docs.smallest.ai/models/speech-to-text/features/utterances.md): Use the utterances array to capture longer segments with speaker labels
- [Speaker diarization](https://docs.smallest.ai/models/speech-to-text/features/diarization.md): Attach zero-indexed speaker labels to each word and utterance in a transcript on Pulse batch and streaming.
- [PII and PCI Redaction](https://docs.smallest.ai/models/speech-to-text/features/redaction.md): Automatically redact sensitive information from transcriptions
- [Gender detection](https://docs.smallest.ai/models/speech-to-text/features/gender-detection.md): Predict speaker gender alongside every transcription
- [Emotion detection](https://docs.smallest.ai/models/speech-to-text/features/emotion-detection.md): Capture per-emotion confidence scores from Pulse STT responses
- [Keyword Boosting](https://docs.smallest.ai/models/speech-to-text/features/keyword-boosting.md): Boost specific words or phrases so the Pulse speech-to-text model recognizes them correctly, on both streaming and pre-recorded transcription.
- [Punctuation Formatting](https://docs.smallest.ai/models/speech-to-text/features/punctuation-formatting.md): Control punctuation and capitalization formatting in real-time transcripts
- [End-of-Utterance Timeout](https://docs.smallest.ai/models/speech-to-text/features/end-of-utterance-timeout.md): Control how long Pulse waits after speech ends before finalizing the transcript
- [Inverse Text Normalization (ITN)](https://docs.smallest.ai/models/speech-to-text/features/inverse-text-normalization.md): Convert spoken-form transcripts into written form in real time
- [Finalize Control](https://docs.smallest.ai/models/speech-to-text/features/finalize-control.md): Word-count finalization parameters on the Pulse STT WebSocket: `finalize_on_words` and `max_words`.
- [Voice Activity (VAD) events](https://docs.smallest.ai/models/speech-to-text/features/vad-events.md): Acoustic `speech_started` / `speech_ended` events emitted on the Pulse STT WebSocket alongside `transcription` messages when `vad_events=true` is set on the connection.
- [Finalization and Endpointing](https://docs.smallest.ai/models/speech-to-text/features/endpointing.md): How the Pulse STT WebSocket decides when a turn is complete. Covers endpointing, eou_timeout_ms, finalize_on_words, and the client-side finalize / close_stream signals in one place.
- [Keep-Alive](https://docs.smallest.ai/models/speech-to-text/features/keep-alive.md): Hold an idle Pulse STT WebSocket open with a `ping` control frame, and understand the inactivity, session, and lifetime limits that apply when no audio is flowing.