Text-to-speech voices
Mastery HQ speaks with one of three engines, chosen in Settings → Voice → Text-to-speech. Turn spoken output on with Enable TTS; add Speak agent output aloud if you also want agent replies voiced, not just the assistant’s.
The three engines
Section titled “The three engines”| Engine (exact option) | Voices | Needs | Notes |
|---|---|---|---|
| System voices — free, offline | A curated set of English voices (up to 5 female + 5 male) from your OS | Nothing | Works offline; quality depends on installed Windows voices |
| OpenAI neural — natural (uses your OpenAI key, ~$0.015/1K chars) | Alloy, Ash, Ballad, Coral, Echo, Nova, Sage, Shimmer, Verse | OpenAI API key (entered under the OpenAI engine section) | Streams MP3 audio; falls back to a system voice until a key is set |
| Grok (xAI) — expressive (uses the xAI key below, ~$0.0042/1K chars) | Eve, Ara, Rex, Sal, Leo | xAI key — paste it in Settings, or leave blank to use XAI_API_KEY from your .env |
Audio is synthesized on the Rust side, so the key never enters the page |
Good to know
Section titled “Good to know”- Speech is a summary channel: spoken output never reads website addresses aloud (a link speaks as its title, bare addresses are skipped) and very long replies are trimmed at a natural sentence. The transcript always keeps the full text — ask for the detail if you want it spoken.
- Cloud engines fail soft: a network or key problem re-speaks the message with the system engine instead of dropping it.
- While anything is being spoken, the reactive LED backlight around the workspace pulses with the speech — a quick visual cue of who’s talking.
- The same Settings section also picks the Assistant brain (what thinks up Hermes’ replies) — that’s a separate choice from what speaks them; see voice settings.