AssemblyAI TTS 1
AssemblyAI's text-to-speech model for voice agents, narration and multilingual applications, with eleven preset voices here.
AssemblyAI's TTS 1 is a cloud text-to-speech model. It converts written text into natural, spoken audio. It offers a choice of 11 voices. It runs through OpenRouter using your own API key, from $0.015 per 1,000 characters.
- Released
- Oct 2026
- Pricing
- $0.015 / 1k chars
- Type
- Text-to-speech
- Voices
- 11 to choose from
Samples
Generated with TTS 1 via OpenRouter: the same three scripts read by every text-to-speech model in the catalog, so the only thing that changes between two models’ clips is the model. Each model uses its own default voice; there is no shared voice to hold constant.
Baseline naturalness and pacing
The last train had already left, but she decided to walk anyway. The city was quieter than she remembered, and for the first time in weeks, she wasn't in a hurry.
Emotion, emphasis, and pauses
Wait — you're telling me it actually worked? After all that? I can't believe it. Honestly, I thought we'd lost the whole thing.
Decimals, percentages, version numbers
The API returned 3,481 results in 0.42 seconds, a 12 percent improvement over version 2.5. Latency at the 99th percentile dropped from 840 milliseconds to 610.
AssemblyAI
AssemblyAI builds speech AI models and APIs, including the Universal speech-to-text models.
www.assemblyai.com ↗