The Audio Tab controls how your agent listens and speaks. Configure languages, choose transcription and voice providers, and tune audio quality. For multilingual agents, you can select different STT and TTS providers per language.Documentation Index
Fetch the complete documentation index at: https://www.bolna.ai/docs/llms.txt
Use this file to discover all available pages before exploring further.
Languages
Set the languages your agent can understand and speak. Pick a primary language and add secondary languages for multilingual conversations.
- Primary Language is marked with
(Primary)and is the language your agent uses at the start of every conversation. The main prompt and multilingual settings are tied to this language. - Secondary Languages allow the agent to understand and respond when a caller switches languages mid-call.
- Click + Add Language to add more languages.
- Remove any language by clicking the x next to it.
Changing the Primary Language
Click the crown icon next to any secondary language to make it primary. A tooltip will confirm the action, for example “Make Hindi primary”. This sets the selected language as the default for the main prompt and multilingual settings.
Supported Languages
| Language | Code |
|---|---|
| English | en |
| Hindi | hi |
| Bengali | bn |
| Assamese | as |
| French | fr |
| Gujarati | gu |
| Indonesian | id |
| Kannada | kn |
| Malay | ms |
| Malayalam | ml |
| Marathi | mr |
| Odia | od |
| Punjabi | pa |
| Spanish | es |
| Tamil | ta |
| Telugu | te |
| Urdu | ur |
| Dutch | nl |
For agents that handle multiple languages in a single call, see the Multilingual Support guide.
Speech-to-Text
Controls how your agent converts the caller’s spoken words into text before the LLM processes them. For multilingual agents, each language can have its own STT provider and model. Select a language tab to configure its transcription settings independently.Different languages may perform better with different providers. For example, use Sarvam for Hindi and Deepgram for English.
Provider and Model
Choose a transcription provider from the Provider dropdown, then pick the specific model from the Model dropdown.| Provider | What it offers |
|---|---|
| AssemblyAI | Real-time transcription with strong punctuation and formatting |
| Azure | Microsoft Azure Speech Services |
| Deepgram | High-accuracy, low-latency transcription with keyword boosting |
| ElevenLabs | Transcription powered by ElevenLabs |
| Gladia | Multilingual transcription service |
| Google Cloud Speech-to-Text | |
| OpenAI | OpenAI Whisper-based transcription |
| Sarvam | Optimized for Indian languages like Hindi, Tamil, and Telugu |
| Smallest | Lightweight, fast transcription provider |
Keywords
Boost recognition accuracy for specific words the transcriber might miss, such as brand names, product names, or technical terms. Enter keywords in the formatword:boost_value (e.g., Bruce:100).
Keyword boosting is only available with Deepgram. The Keywords field has no effect when using other providers.
Text-to-Speech
Controls how your agent sounds when speaking to the caller. For multilingual agents, each language can have its own TTS provider, model, and voice. Select a language tab to configure voice settings independently.
Provider, Model, and Voice
Pick a Model
Select the model that fits your latency and quality needs (e.g., ElevenLabs
eleven_turbo_v2_5 for low latency).Browsing Voices
Click the Voice dropdown to see a searchable list of all available voices. Filter by gender using the All, Male, Female, and Neutral tabs. Each voice shows a play button so you can preview it before selecting.
Preview Welcome Message
Click Preview welcome message to hear the selected voice speak your agent’s welcome prompt (configured in the Agent Tab). This lets you test how the voice sounds before going live.Voice Tuning Parameters
Fine-tune your agent’s voice using the sliders below the voice selector. Available parameters may vary by provider.| Parameter | What it controls |
|---|---|
| Buffer Size | Audio buffered before playback begins. Higher values produce smoother audio but increase delay. Values between 150 and 250 work well for real-time conversations. |
| Speed Rate | Speaking speed. 1 is natural pace, above 1 is faster, below 1 is slower. |
| Similarity Boost | How closely the output matches the original voice sample. Higher values are more faithful but may reduce naturalness. |
| Stability | Voice consistency across sentences. Higher values keep tone steady, lower values add expressive variation. |
| Style Exaggeration | Emphasis on stylistic characteristics. 0 is neutral, higher values add more personality. |
Adding and Cloning Voices
Click the Add Voice + button in the Text-to-Speech section to add a custom voice by ID or clone one from an audio sample.Custom voice uploads are only available for ElevenLabs and Cartesia.
Add a Voice by ID
Use this when you already have a voice ID from your provider’s voice library.
Enter the Voice ID
Paste the voice ID from your provider. For ElevenLabs, find IDs in the ElevenLabs voice library.
Clone a Voice
Create a new voice by uploading an audio recording. Useful for maintaining a consistent brand voice or using a specific person’s voice (with their permission).
Enter Voice Details
Add a Voice name (e.g., “Sales Assistant Voice”) and Description (e.g., “Warm male Indian accent”).
Upload an Audio Sample
Drag and drop your audio file or click click to browse. Audio files only, maximum 10 MB.
Supported Languages for Voice Cloning
Both ElevenLabs and Cartesia support the same set of languages for cloning:| Language | Code | Language | Code |
|---|---|---|---|
| English | en | Hindi | hi |
| Bengali | bn | Assamese | as |
| Dutch | nl | French | fr |
| Gujarati | gu | Indonesian | id |
| Kannada | kn | Malay | ms |
| Malayalam | ml | Marathi | mr |
| Odia | od | Punjabi | pa |
| Spanish | es | Tamil | ta |
| Telugu | te | Urdu | ur |
| Indian Multilingual | - |
Next Steps
Engine Tab
Configure interruption handling, endpointing, and latency
Multilingual Support
Set up agents that speak multiple languages in a single call
Clone Voices
Create a custom voice from an audio sample
Deepgram Provider
Explore Deepgram transcription models and keyword boosting