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Text to SpeechBenchmarks

Lightning benchmarks

Latency, listener ratings, accuracy and MOS for Lightning v3.1 and Pro, one page each.
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Head-to-head listener evaluation against production TTS systems on the EmergentTTS benchmark, 1,088 samples scored by the LLM-as-a-Judge framework. Tables below pair Lightning v3.1 (Standard) and Lightning v3.1 Pro with the same competitor set across Naturalness, Expressiveness, Delivery, Accuracy, and MOS v2 categories. Open the accordion under each one to see what each metric measures, or read the full Metrics Overview.

Benchmarks

Latency

Time to first byte and real-time factor for Lightning v3.1 and Pro.

Listener ratings

Head-to-head naturalness, expressiveness and delivery ratings.

Accuracy

Pronunciation accuracy measured with Whisper jiwer and Whisper LLM.

MOS

Mean opinion score v2 for Lightning v3.1 and Pro.

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