> ## Documentation Index
> Fetch the complete documentation index at: https://blackbox.dasha.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Add Active Listening Cues to Conversations

> Enable your Dasha BlackBox voice agent to produce active listening cues like 'mm-hmm', 'I see', and 'right' while callers speak. Create more engaging, natural conversations with intelligent backchannel responses.

Signal active listening with natural cues. Backchannel phrases like "mm-hmm" and "I see" reassure callers the agent is engaged, encouraging them to share more details.

**What you'll learn:** Backchannel modes (static, dynamic, LLM), phrase configuration, and frequency tuning.

## Why Use Backchannel?

### Signals Active Engagement

Backchannel responses reassure callers that the agent is listening and processing what they say. This is especially important during longer caller explanations.

### Improves Conversation Flow

Active listening cues create natural rhythm in conversations. They encourage callers to continue speaking and provide more detailed information.

### Increases Perceived Empathy

Backchannel responses make agents seem more empathetic and understanding, particularly important for support and service conversations.

### Reduces Caller Uncertainty

When callers share information and hear nothing in response, they often wonder if the agent is still listening or if the call dropped. Backchannel eliminates this uncertainty.

## How to Configure Backchannel

Dasha BlackBox offers three backchannel modes with increasing sophistication:

### Mode 1: Static (Simple)

Basic backchannel with a list of phrases and frequency control.

#### Configuration Steps

1. Open your agent's configuration
2. Navigate to the **Features** tab
3. Find **Backchannel** and toggle it on
4. Select **Static** mode

#### Settings

**Backchannel Phrases** - Add phrases the agent should use:

* "Mm-hmm"
* "I see"
* "Right"
* "Okay"
* "Got it"
* "I understand"

**Frequency** - Value from 0.0 to 1.0:

* **0.25**: Infrequent, occasional acknowledgment
* **0.5**: Moderate, balanced approach (recommended starting point)
* **0.75**: Frequent, very engaged listening

**Recommended starting configuration:**

* 5-6 varied phrases
* Frequency: 0.4-0.6

### Mode 2: Static Advanced (Precise Control)

Full control over backchannel timing and behavior.

#### Configuration Steps

1. Enable backchannel and select **Static Advanced** mode
2. Configure detailed timing parameters

<Accordion title="Settings">
  **Backchannel Phrases** - Same as Static mode, add multiple varied phrases

  **Minimum Voice Length** (`minLengthVoice`, seconds)

  * How long the caller must speak before backchannel can occur

  * Minimum: 1 second

  * Recommended: 3-5 seconds (prevents interrupting short statements)

  **Voice Length Deviation** (`minLengthVoiceDeviation`, 0.0-1.0)

  * Randomization of the minimum voice length

  * 0.2 deviation means timing varies ±20% for naturalness

  * Recommended: 0.15-0.25 for natural variation

  **Frequency** (`frequency`, 0.0-1.0)

  * Chance of backchannel occurring when conditions are met

  * Recommended: 0.4-0.6 (not every eligible moment gets a response)

  **Minimum Cooldown** (`minCooldown`, seconds)

  * Required time between backchannel responses

  * Minimum: 1 second

  * Prevents excessive acknowledgments

  * Recommended: 4-8 seconds

  **Cooldown Deviation** (`minCooldownDeviation`, 0.0-1.0)

  * Randomization of cooldown timing

  * Recommended: 0.2-0.3 for natural unpredictability

  **Example Advanced Configuration:**

  ```json theme={"theme":{"light":"github-light","dark":"github-dark"}}
  {
    "isEnabled": true,
    "behavior": {
      "type": "staticAdvanced",
      "phrases": ["Mm-hmm", "I see", "Right", "Okay", "I understand", "Go on"],
      "minLengthVoice": 4,
      "minLengthVoiceDeviation": 0.2,
      "frequency": 0.5,
      "minCooldown": 6,
      "minCooldownDeviation": 0.25
    }
  }
  ```
</Accordion>

### Mode 3: Smart V1 (AI-Generated)

Language model generates contextually appropriate backchannel responses.

#### Configuration Steps

1. Enable backchannel and select **Smart V1** mode
2. Optionally add instructions to guide the language model

#### Settings

**Additional Instructions** (optional)

* Guide the model's backchannel behavior
* Example: "Use professional acknowledgments appropriate for healthcare"
* Example: "Be empathetic and supportive when caller describes problems"
* Example: "Keep responses very brief—1-2 words maximum"

#### How Smart Mode Works

The language model analyzes:

* What the caller is saying
* Emotional tone of the conversation
* Appropriate moments for acknowledgment
* Contextually relevant responses

Instead of random selection from a phrase list, Smart mode generates responses like:

* "That makes sense"
* "I can help with that"
* "I understand your concern"
* "Tell me more"

**Advantages:**

* Context-aware responses
* More natural and varied
* Can adapt to conversation tone

**Considerations:**

* Slightly higher latency (generating responses takes time)
* Uses more language model resources
* May occasionally generate longer responses than desired

## Configuration Examples

<Accordion title="Example: Customer Support (Static)">
  ```json theme={"theme":{"light":"github-light","dark":"github-dark"}}
  {
    "isEnabled": true,
    "behavior": {
      "type": "static",
      "phrases": [
        "Mm-hmm",
        "I see",
        "I understand",
        "Got it",
        "Okay"
      ],
      "frequency": 0.5
    }
  }
  ```

  **Result:** Balanced, professional acknowledgment during customer explanations.
</Accordion>

<Accordion title="Example: Healthcare (Static Advanced)">
  ```json theme={"theme":{"light":"github-light","dark":"github-dark"}}
  {
    "isEnabled": true,
    "behavior": {
      "type": "staticAdvanced",
      "phrases": [
        "Mm-hmm",
        "I understand",
        "I see",
        "Please continue"
      ],
      "minLengthVoice": 5,
      "minLengthVoiceDeviation": 0.15,
      "frequency": 0.45,
      "minCooldown": 7,
      "minCooldownDeviation": 0.2
    }
  }
  ```

  **Result:** Careful, measured responses appropriate for medical conversations. Longer pauses allow patients to fully explain symptoms.
</Accordion>

<Accordion title="Example: Empathetic Support (Smart V1)">
  ```json theme={"theme":{"light":"github-light","dark":"github-dark"}}
  {
    "isEnabled": true,
    "behavior": {
      "type": "smartV1",
      "additionalInstructions": "Provide empathetic, supportive acknowledgments. When the caller describes problems or frustrations, respond with understanding and validation."
    }
  }
  ```

  **Result:** Context-aware, empathetic responses that adapt to caller emotions and conversation content.
</Accordion>

## Common Use Cases

### Customer Support (Problem Description)

* **Configuration:** Static mode, 0.5 frequency, empathetic phrases
* **Why:** Callers explain problems at length; backchannel shows agent is listening and cares

### Healthcare Appointments

* **Configuration:** Static Advanced, longer voice length, lower frequency (0.4)
* **Why:** Patients need space to fully describe symptoms without interruption

### Sales Discovery Calls

* **Configuration:** Static mode, 0.55-0.6 frequency, encouraging phrases
* **Why:** Encourages prospects to share more information; builds rapport

### Survey and Research

* **Configuration:** Smart V1 mode with supportive instructions
* **Why:** Contextual responses show genuine interest in respondent's answers

### Technical Support

* **Configuration:** Static mode, 0.45 frequency, understanding phrases
* **Why:** Acknowledges complex technical descriptions without interrupting troubleshooting flow

## Technical Considerations

### Voice Activity Detection

Backchannel relies on detecting when callers are speaking. The system monitors:

* Voice activity duration
* Pauses in caller speech
* Natural conversation rhythm

Backchannel occurs during natural pauses while the caller is still actively speaking (not during silent gaps between turns).

### Timing and Latency

* **Static modes**: Near-instant backchannel responses
* **Smart V1 mode**: Slight delay (0.5-1.5 seconds) for language model generation

### Speech Mixing

Backchannel responses are mixed with ongoing caller speech at reduced volume, similar to how humans layer acknowledgments over others' speech without fully interrupting.

### Compatibility

Backchannel works across all call types:

* ✅ Outbound phone calls
* ✅ Inbound phone calls
* ✅ Web-based voice calls
* ✅ All voice vendors

## Troubleshooting

### Problem: Too Many Backchannel Responses

**Solution:** Reduce frequency to 0.35-0.45 or increase minimum cooldown. Some conversations need less acknowledgment.

### Problem: Backchannel Interrupts Callers

**Solution:** Increase minimum voice length to 5-6 seconds. This ensures callers speak longer before backchannel occurs.

### Problem: Same Phrase Repeats Too Often

**Solution:** Add more varied phrases (target 6-8 different options). More variety prevents noticeable patterns.

### Problem: Backchannel Doesn't Occur

**Solution:** Verify backchannel is enabled. Increase frequency percentage. Ensure callers are speaking for minimum voice length duration.

### Problem: Smart Mode Responses Too Long

**Solution:** Add instructions like "Keep responses to 1-2 words maximum" or "Use only brief acknowledgments like 'mm-hmm' or 'I see'".

## Measuring Effectiveness

Track these metrics to evaluate backchannel impact:

* **Call completion rate** - Better engagement may improve completions
* **Average caller explanation length** - More backchannel often encourages longer, more detailed responses
* **Caller satisfaction scores** - Active listening improves satisfaction
* **Perceived agent empathy** - Survey callers about how well agent listened

## Next steps

<CardGroup cols={2}>
  <Card title="Fillers" icon="hourglass-half" href="/docs/advanced-features/fillers">
    Add verbal pauses during processing
  </Card>

  <Card title="Ambient Noise" icon="volume-low" href="/docs/advanced-features/ambient-noise">
    Add realistic background sounds
  </Card>

  <Card title="Talk First" icon="message" href="/docs/advanced-features/talk-first">
    Control opening greetings
  </Card>

  <Card title="Voice & Speech" icon="microphone" href="/docs/create/voice-and-speech">
    Configure voice settings
  </Card>
</CardGroup>