AssemblyAI Launches Its First TTS Model, TTS-1

On October 28, AssemblyAI officially released its first text-to-speech model, AssemblyAI-TTS-1, positioned for real-time conversational voice agents and available the same day. Official specs include roughly 90ms first-audio latency (a repost alternatively cited 80ms first-byte/TTFB—slightly different framings), pricing of $15 per million characters, instant voice cloning with 4,000+ preset voices, and streaming latency on the order of 90 milliseconds. The company claims no other TTS model simultaneously beats it on accuracy, naturalness, and cost, making it the best TTS for running at scale.

Confirmed

• Release and date: announced by AssemblyAI's official account on October 28; TTS-1 available immediately
• Pricing: $15 per million characters
• Latency: officially 90ms first audio / streaming output (a repost cited 80ms first byte)
• Features: 4,000+ preset voices, instant voice cloning, built for real-time voice agents
• Third-party evaluation: Artificial Analysis benchmarked it across multiple arenas—generation speed of 162 characters/second ranks near the top; Provider Voice Arena Elo of 1,227 (1,626 appearances), placing in the top twelve of both the Provider Voice Arena and Controlled Voice Arena

Unconfirmed

• The official post and repost differ on latency: 80ms (first byte) vs. 90ms (first audio) may reflect different measurement definitions; awaiting official clarification

Why it matters

TTS-1 is AssemblyAI's first product extending from speech recognition/understanding into speech synthesis, targeting the hot voice agent market with a low-latency, low-cost combo. Artificial Analysis's independent evaluation backs up its speed and arena rankings, but the "best overall" claim is the vendor's own—real-world performance needs more head-to-head validation.

2026-10-28 ~ 2026-10-29 · 5 related posts

Full story(2 episodes)→

• Episode 1: AssemblyAI Launches Its First TTS Model, TTS-1(2026-10-28, 5 posts)
• Episode 2: AssemblyAI-TTS-1 tops TTS speed benchmark at 162 chars/sec but ranks 16th in pronunciation robustness(2026-10-29, 5 posts)

• AssemblyAI launches first TTS model: 80ms TTFB, 4,000+ voices, $15/1M chars — ycombinator · 2026-10-28
• AssemblyAI launches its first TTS model, entering top 12 in both voice arenas — ArtificialAnlys · 2026-10-29

3 near-duplicate retellings: AssemblyAI · AssemblyAI · ArtificialAnlys