Custom vocabulary for dictation
Speech engines are trained on general language. They struggle with proper nouns, brand names, acronyms, and technical jargon. Mumbli lets you fix that.The problem
Without custom vocabulary, speech engines make predictable mistakes:
These errors are consistent — the same word gets mistranscribed the same way every time.
The fix
Open Settings > Custom Vocabulary and add the words that matter to you. Mumbli uses them at two levels:1
Transcription hints
Your vocabulary is sent as a prompt hint to the speech-to-text engine (Groq Whisper). This biases the transcription toward your preferred spellings before any text is generated.
2
Polishing corrections
Your vocabulary is injected into the LLM polishing prompt. Even if the transcription engine still gets it wrong, the polisher knows what you meant and corrects it.
Benchmarked results
We tested 11 real vocabulary instances that were consistently mistranscribed:
Every single test word was transcribed correctly after adding it to the vocabulary list.
What to add
Good candidates for your vocabulary list:- People’s names — colleagues, contacts, public figures
- Brand names — products, companies, services you mention often
- Technical terms — frameworks, libraries, CLI tools, protocols
- Acronyms — spelled out the way you want them (e.g., “GROQ” not “grock”)
- Domain-specific jargon — medical terms, legal terms, industry language
Engine support
ElevenLabs Scribe v1 and the current Deepgram path do not use vocabulary hints at the STT level, so corrections happen during polishing only. Groq Whisper supports hints at both levels.
Download Mumbli
Free and open source. Add your vocabulary in Settings after install.