Soniox TTS RT v1 Soniox · text-to-speech (TTS) API

Speed

On Coval's 30-day window ending October 22, 2026 (2,962 runs from US East), Soniox TTS RT v1 starts speaking after 259.9 ms on a typical turn (median) and 320.4 ms on a slow turn (P95, the slowest one in twenty). That P95 is 14th lowest of the 32 models Coval measures, which puts it in the Visible delay tier: the voice becomes a visible part of the delay. On the median it is a tie (gap under 10 ms) with Deepgram Aura 2, Rime Mist v3 and Soniox TTS Real-Time v2.

Voice quality

Speko rates its naturalness at 1,569 Elo from blind A/B votes on phone-agent lines (13th highest of the 43 models Speko rates).

Numbers and dates

Speko's pronunciation test on numbers, dates and currency scores it 0.35 on a 0-to-1 scale (12th 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.

Price

Coval lists $14.1 per 1M characters (since Sep 22, 2026). Speko lists about $13. List prices, as each source prints them: a range of $13 to $14.1.

Languages tested

Tested in Spanish, German and French by Artificial Analysis or Speko. A language missing here was not tested, which does not mean it is unsupported.