Inworld Realtime TTS-2
Inworld Realtime TTS-2 is a proprietary text-to-speech (TTS) API from Inworld, measured by three independent benchmarks: Artificial Analysis, Coval and Speko.
109 ms median and 205 ms P95 time to first audio on Coval (30 days to October 22, 2026): Fast enough speed tier.
Benchmark summary: Fast enough speed tier on Coval's P95 (fast enough for most agents), a tie within 10 ms with Fish Audio Drama 3 Preview and Inworld Realtime TTS-2 on slow turns.
Palabra TTS v1 is a proprietary text-to-speech (TTS) API from Palabra, measured by two independent benchmarks: Coval and Speko.
Speed tier
Fast enoughP95 from 138 ms to 263 ms. Fast enough for most agents.
Data read October 22, 2026. No combined score: methodology
Gradium TTS vs Palabra TTS v1 Fastest TTS APIs, by speed tierOn Coval's 30-day window ending October 22, 2026 (2,898 runs from US East), Palabra TTS v1 starts speaking after 109.2 ms on a typical turn (median) and 205.3 ms on a slow turn (P95, the slowest one in twenty). That P95 is 9th lowest of the 32 models Coval measures, which puts it in the Fast enough tier: fast enough for most agents. On the median it is a tie (gap under 10 ms) with Alibaba Qwen3 TTS 1.7b, SpeechifyAI Simba 3.0 and SpeechifyAI Simba 3.2. Speko's board plots it at 86 ms time to first audio from US East; its model page reports a 72 ms sweep.
Speko rates its naturalness at 1,520 Elo from blind A/B votes on phone-agent lines (21st highest of the 43 models Speko rates).
Speko's pronunciation test on numbers, dates and currency scores it 0.16 on a 0-to-1 scale (28th highest of the 30 models Speko scores). This is the accuracy measure used here; Coval's word error rate separates models too little to compare them.
Coval lists $12 per 1M characters (since Oct 13, 2026). Speko lists about $12. List prices, as each source prints them.
Inworld Realtime TTS-2 is a proprietary text-to-speech (TTS) API from Inworld, measured by three independent benchmarks: Artificial Analysis, Coval and Speko.
Fish Audio Drama 3 Preview is an open-weights text-to-speech (TTS) API from Fish Audio, measured by two independent benchmarks: Artificial Analysis and Coval.
SpeechifyAI Simba 3.2 is a proprietary text-to-speech (TTS) API from Speechify, measured by three independent benchmarks: Artificial Analysis, Coval and Speko.