Voices and speech

The SIMCOAI voices by name, the SIMCOAI speech engines that listen, and what to change when either is not working well.

Voices

The SIMCOAI voices

These are the voices your callers hear. The trade is the same one every time: a faster voice starts speaking sooner, a richer voice sounds less like a machine. Which are available depends on your plan.

VoiceWhat it is for
SIMCOAI Vox Clara 1.5Responsive, clear speech for everyday conversations, browser demos and compatible live calls.
SIMCOAI Vox Magna 1.5Richer speech for narration, greetings and compatible live calls on Pro or with SIMCOAI Voices.
Voice identity

Choose the voice your callers actually hear

The voice picker uses the available speaking voice names, including Alice, Lily, Daniel, George and River where available on your plan. These are separate from the speech engine settings.

In Phone Numbers, choose Use Call Studio voice to follow your saved account voice or rotation setting. Choose a specific voice there only when that number should override Call Studio. Changes apply to new calls.

Speech

The SIMCOAI speech engines

How SIMCOAI understands what a caller said - including when they have finished saying it, which is what stops the assistant talking over somebody.

EngineWhat it is for
SIMCOAI Auditus Vivus 1.5Current-generation live transcription with SIMCOAI turn-taking controls.
SIMCOAI Auditus Certus 1.5Best for accurately transcribing names, addresses and reference numbers.
SIMCOAI Auditus Communis 1.5Current-generation transcription for recorded messages and general audio.
As with the models, these are SIMCOAI configurations rather than engines SIMCOAI built - see AI models for what that means, and the privacy policy for who processes what.
Choosing

Picking a voice

Call Studio shows the voice models supported by your current call setup. Version 1.5 is used for browser speech and compatible live lines; other lines retain their supported version-1 voice until upgraded.

  1. Open your call settingsVoice options sit alongside greeting and speech settings.
  2. PreviewListen before you apply. A voice that reads well can still sound wrong for your brand.
  3. ApplyThe voice takes effect on the next call, not mid-call.
  4. Test on a real callPreview text is short. A real conversation exposes pacing you will not hear in a sample.
Random

Rotating the voice

You can let SIMCOAI vary the voice rather than always using the same one.

SettingBehaviour
Fixed voiceEvery call uses the voice you selected
RotatingSIMCOAI picks from the voices available on your plan, once per call
Careful. Rotating needs at least two voices available to do anything. With one it behaves identically to a fixed voice.
Hearing

When a caller is hard to understand

Speech settings affect how quickly SIMCOAI decides a caller has finished speaking. That trade-off is real: react too fast and you interrupt, too slow and the call feels sluggish.

  • Noisy environments — callers on speakerphone or in a workshop produce more interim results and more false endpoints.
  • Long pauses — callers reading an order number aloud often pause mid-sequence.
  • Accents and speed — test with voices representative of your actual customers, not just your own.
Judging

Was it any good?

Every call records measurable signals rather than leaving you to guess. See call quality signals for first-reply latency, interruption handling and finish reasons.