> 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.

# Benchmarks

## Docs

- [Lightning benchmarks](https://docs.smallest.ai/models/text-to-speech/benchmarks/performance.md): Overview of Lightning v3.1 and Lightning v3.1 Pro text-to-speech benchmarks: latency, listener ratings, pronunciation accuracy and MOS.
- [Latency](https://docs.smallest.ai/models/text-to-speech/benchmarks/latency.md): Lightning v3.1 and Lightning v3.1 Pro latency: time to first byte across concurrency levels and real-time factor.
- [Listener ratings](https://docs.smallest.ai/models/text-to-speech/benchmarks/listener-ratings.md): Lightning v3.1 and Lightning v3.1 Pro head-to-head listener ratings for naturalness, expressiveness and delivery against other text-to-speech providers.
- [Accuracy](https://docs.smallest.ai/models/text-to-speech/benchmarks/accuracy.md): Lightning text-to-speech pronunciation accuracy measured by transcribing the output with Whisper: jiwer word error rate and an LLM-judged score.
- [MOS](https://docs.smallest.ai/models/text-to-speech/benchmarks/mos.md): Lightning v3.1 and Lightning v3.1 Pro mean opinion score (MOS v2) compared with other text-to-speech providers.
- [Metrics Overview](https://docs.smallest.ai/models/text-to-speech/benchmarks/metrics-overview.md): Definitions of every Lightning v3.1 TTS quality and latency metric - Naturalness, Expressiveness, Delivery, Accuracy, and MOS variants.