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

# FAQ

> Frequently asked questions about VoxNexus voice services

## General Questions

### What is VoxNexus?

VoxNexus is a comprehensive voice services platform that provides Text-to-Speech (TTS) and Speech-to-Text (STT) capabilities through easy-to-use APIs. Our platform enables developers to add natural voice synthesis and accurate speech recognition to their applications.

### What languages are supported?

VoxNexus supports 50+ languages including English, Chinese, Spanish, French, German, Japanese, Korean, and many more. We continuously add new languages and regional variants to our voice library.

### How accurate is the speech recognition?

Our Speech-to-Text service achieves high accuracy rates, typically above 95% for clear audio in supported languages. Accuracy can vary based on audio quality, background noise, speaker accent, and language complexity.

### How natural do the voices sound?

Our Text-to-Speech voices are generated using advanced AI models and sound very natural. Voice quality is comparable to human narration, with natural intonation, rhythm, and pronunciation.

## Getting Started

### How do I get an API key?

1. Sign up for a free account at [voxnexus.ai/dashboard](https://voxnexus.ai/dashboard)
2. Navigate to the API Keys section
3. Create a new API key
4. Copy and securely store your API key

### Is there a free tier?

Yes, we offer a free tier with limited usage. Check our [pricing page](https://voxnexus.ai/pricing) for details on free tier limits and paid plans.

### How quickly can I get started?

You can get started in minutes! Simply:

1. Sign up for an account
2. Get your API key
3. Make your first API call
4. See our [Quick Start Guide](/quickstart) for detailed steps

## API Usage

### What's the difference between REST API and WebSocket API?

* **REST API**: Best for standard request-response scenarios. Supports both synchronous and streaming responses. Use for batch processing, file uploads, and standard integrations.
* **WebSocket API**: Ideal for real-time bidirectional communication. Lower latency, persistent connection. Use for live transcription, real-time voice synthesis, and interactive applications.

### How do I handle audio files?

For Speech-to-Text, you can send audio files directly in the request body. Supported formats include WAV, MP3, PCM, and OGG. For Text-to-Speech, audio is returned in the response body in your requested format.

### What audio formats are supported?

**Text-to-Speech output formats:**

* MP3 (compressed, web-friendly)
* WAV (uncompressed, high quality)
* OGG (open-source compressed)
* PCM (raw audio data)
* WebM (web-optimized)

**Speech-to-Text input formats:**

* WAV
* MP3
* PCM
* OGG
* application/octet-stream

### How do I specify the language?

For Text-to-Speech, specify the language using the `language` parameter (ISO 639-1 format):

```json theme={null}
{
  "text": "Hello",
  "voice_id": "vn-jenny",
  "language": "en-US"
}
```

For Speech-to-Text, specify via query parameter:

```bash theme={null}
curl -X POST "https://api.voxnexus.ai/v1/stt?model_id=vn-stt-ultra&language=en-US&sample_rate=16000" \
  -H "X-Api-Key: YOUR_API_KEY" \
  -H "Content-Type: audio/wav" \
  --data-binary @audio.wav
```

If not specified, the service will attempt to auto-detect the language.

## Voice Selection

### How do I choose the right voice?

Consider these factors:

1. **Language**: Choose a voice that matches your content language
2. **Gender**: Select based on your application's needs
3. **Age**: Match voice age to your target audience
4. **Style**: Choose professional, casual, cheerful, etc.
5. **Test**: Always test voices with sample content

Use our [Voice Library](/voices) to browse and filter voices.

### Can I customize voices?

Yes! You can customize:

* **Speed**: Adjust speech rate (0.5x to 2.0x)
* **Pitch**: Modify pitch in semitones (-12 to +12)
* **Volume**: Set volume multiplier (0.0 to 1.0)
* **Voice Config**: Some voices support style, role, and other parameters

### Do voices support SSML?

Yes! Enable SSML support by setting `ssml: true`:

```json theme={null}
{
  "text": "<speak>Hello <break time='500ms'/> world</speak>",
  "voice_id": "vn-xiaoxiao",
  "ssml": true
}
```

## Speech Recognition

### What is speaker diarization?

Speaker diarization identifies different speakers in multi-speaker audio. Enable it with:

```bash theme={null}
curl -X POST "https://api.voxnexus.ai/v1/stt?model_id=vn-stt-ultra&sample_rate=16000&enable_speaker_diarization=true" \
  -H "X-Api-Key: YOUR_API_KEY" \
  -H "Content-Type: audio/wav" \
  --data-binary @meeting.wav
```

### How do I get word-level timestamps?

Enable timestamps in your request:

```bash theme={null}
curl -X POST "https://api.voxnexus.ai/v1/stt?model_id=vn-stt-ultra&sample_rate=16000&enable_timestamps=true" \
  -H "X-Api-Key: YOUR_API_KEY" \
  -H "Content-Type: audio/wav" \
  --data-binary @audio.wav
```

### Can I improve recognition accuracy?

Yes, several ways:

1. **Specify language**: Always specify the language when known
2. **Use high-quality audio**: Better audio quality = better accuracy
3. **Add keywords**: Use the `keywords` parameter for important terms
4. **Custom vocabulary**: Add domain-specific terms
5. **Enable confidence scores**: Identify uncertain segments

### What sample rates are supported?

Supported sample rates: 8000, 16000, 22050, 24000, 44100, 48000 Hz.

* **8kHz**: Telephony quality
* **16kHz**: Standard quality (recommended for most use cases)
* **44.1kHz/48kHz**: High-quality audio

## Pricing & Limits

### How is pricing calculated?

Pricing is based on usage:

* **Text-to-Speech**: Charged per character or audio duration
* **Speech-to-Text**: Charged per audio minute processed
* **Rate Limits**: Based on your plan tier

Check response headers for usage information:

* `X-Quota-Used`: Credits consumed
* `X-RateLimit-Remaining`: Remaining requests

### What happens if I exceed my quota?

When you exceed your quota, API requests will return a `429` status code. Upgrade your plan or wait for quota reset to continue.

### Can I monitor my usage?

Yes! Usage information is included in response headers:

* `X-RateLimit-Remaining`: Remaining requests
* `X-Quota-Used`: Credits consumed

You can also check usage in your [Dashboard](https://voxnexus.ai/dashboard).

## Technical Questions

### How do I handle errors?

All errors follow a consistent format:

```json theme={null}
{
  "error": "Error description",
  "code": "ERROR_CODE",
  "details": "Additional details",
  "request_id": "req_1234567890"
}
```

Common HTTP status codes:

* `400`: Bad Request (invalid parameters)
* `401`: Unauthorized (invalid API key)
* `429`: Rate Limit Exceeded
* `500`: Server Error

### How do I implement retry logic?

Implement exponential backoff for retries:

```javascript theme={null}
async function makeRequestWithRetry(url, options, maxRetries = 3) {
  for (let i = 0; i < maxRetries; i++) {
    try {
      const response = await fetch(url, options);
      if (response.ok) return response;
      
      if (response.status === 429) {
        const delay = Math.pow(2, i) * 1000; // Exponential backoff
        await new Promise(resolve => setTimeout(resolve, delay));
        continue;
      }
      
      throw new Error(`HTTP ${response.status}`);
    } catch (error) {
      if (i === maxRetries - 1) throw error;
      await new Promise(resolve => setTimeout(resolve, 1000 * (i + 1)));
    }
  }
}
```

### How do I stream audio responses?

Text-to-Speech responses use chunked transfer encoding by default. Handle streaming:

```javascript theme={null}
const response = await fetch('https://api.voxnexus.ai/v1/tts', {
  method: 'POST',
  headers: {
    'Authorization': 'Bearer YOUR_API_KEY',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    text: 'Long text here...',
    voice_id: 'vn-xiaoxiao'
  })
});

const reader = response.body.getReader();
const chunks = [];

while (true) {
  const { done, value } = await reader.read();
  if (done) break;
  chunks.push(value);
}

// Combine chunks and play
const audioBlob = new Blob(chunks, { type: 'audio/mpeg' });
```

### How do I handle WebSocket reconnections?

Implement reconnection logic:

```javascript theme={null}
class ReconnectingWebSocket {
  constructor(url, options) {
    this.url = url;
    this.options = options;
    this.reconnectAttempts = 0;
    this.maxAttempts = 5;
    this.connect();
  }
  
  connect() {
    this.ws = new WebSocket(this.url, this.options);
    
    this.ws.onclose = () => {
      if (this.reconnectAttempts < this.maxAttempts) {
        setTimeout(() => {
          this.reconnectAttempts++;
          this.connect();
        }, Math.pow(2, this.reconnectAttempts) * 1000);
      }
    };
    
    this.ws.onopen = () => {
      this.reconnectAttempts = 0;
    };
  }
}
```

## Security & Privacy

### Is my data secure?

Yes! We take security seriously:

* **Encryption**: All data encrypted in transit (TLS/SSL)
* **No Storage**: Audio data is not stored after processing
* **API Keys**: Secure key management and rotation
* **GDPR Compliant**: Meets data protection regulations

### Do you store my audio files?

No. Audio files are processed and immediately discarded. We do not store your audio data.

### How do I secure my API key?

Best practices:

1. **Never commit keys to version control**
2. **Use environment variables**
3. **Rotate keys regularly**
4. **Use different keys for different environments**
5. **Monitor key usage**

## Support

### Where can I get help?

* **Documentation**: Browse our comprehensive docs
* **Email Support**: [support@voxnexus.ai](mailto:support@voxnexus.ai)
* **Dashboard**: Manage your account and view usage
* **Status Page**: Check service status

### How do I report bugs?

Report bugs via email to [support@voxnexus.ai](mailto:support@voxnexus.ai). Include:

* API endpoint used
* Request details (without sensitive data)
* Error response
* Steps to reproduce

## Next Steps

<CardGroup cols={2}>
  <Card title="Quick Start" icon="rocket" href="/quickstart">
    Get started with VoxNexus
  </Card>

  <Card title="API Reference" icon="code" href="/api-reference/introduction">
    Explore API documentation
  </Card>

  <Card title="Features" icon="star" href="/features">
    Learn about platform features
  </Card>

  <Card title="Use Cases" icon="lightbulb" href="/use-cases">
    See real-world applications
  </Card>
</CardGroup>