hearken 0.4.0
Robust speech recognition pipeline that prevents audio drops
License: Apache 2.0
Requires Python: >=3.11
Keywords: audio, speech-recognition, transcription, vad, voice

# Hearken

Robust speech recognition pipeline for Python that prevents audio drops during transcription.

## The Problem

In typical speech detection programs, audio capture is blocked during transcription. This causes dropped frames when network I/O is slow, resulting in missed speech.

## The Solution

Hearken decouples capture, voice activity detection (VAD), and transcription into independent threads with queue-based communication. The capture thread never blocks, preventing audio loss even during slow transcription.

## Installation

```bash
# Basic installation (includes EnergyVAD)
pip install hearken

# With speech_recognition support
pip install hearken[sr]

# With WebRTC VAD support
pip install hearken[webrtc]

# With Silero VAD support (neural network)
pip install hearken[silero]

# All optional dependencies
pip install hearken[all]
```

## Quick Start

```python
import speech_recognition as sr
from hearken import Listener, EnergyVAD
from hearken.adapters.sr import SpeechRecognitionSource, SRTranscriber

# Setup
recognizer = sr.Recognizer()
mic = sr.Microphone()

with mic as source:
    recognizer.adjust_for_ambient_noise(source)

# Create listener
listener = Listener(
    source=SpeechRecognitionSource(mic),
    transcriber=SRTranscriber(recognizer),
    on_transcript=lambda text, seg: print(f"You said: {text}")
)

# Run
listener.start()
try:
    listener.wait()
except KeyboardInterrupt:
    listener.stop()
```

## Features

- **No dropped frames**: Capture thread never blocks on downstream processing
- **Two modes**: Passive (callbacks) and active (`wait_for_speech()`)
- **Clean abstractions**: Bring your own audio source and transcriber
- **Production-ready FSM**: Robust 4-state detector filters false starts and handles pauses

### Voice Activity Detection (VAD)

- **EnergyVAD**: Simple energy-based detection with dynamic threshold calibration
- **WebRTCVAD**: Google WebRTC VAD for improved accuracy in noisy environments
  - Requires sample rates: 8000, 16000, 32000, or 48000 Hz
  - Configurable aggressiveness (0-3)
  - Install with: `pip install hearken[webrtc]`
- **SileroVAD**: Neural network-based VAD for superior accuracy
  - Requires 16kHz audio
  - Configurable sensitivity threshold
  - Automatic model download and caching
  - Install with: `pip install hearken[silero]`

## Architecture

```
Microphone → [Capture Thread] → Queue → [Detect Thread] → Queue → [Transcribe Thread] → Callback
                   ↓                          ↓                         ↓
            AudioChunk (30ms)      SpeechSegment (complete)    Text transcription
```

## Active Mode

```python
listener = Listener(
    source=SpeechRecognitionSource(mic),
    transcriber=SRTranscriber(recognizer),
)

listener.start()

while True:
    print("Waiting for speech...")
    segment = listener.wait_for_speech()

    if segment:
        try:
            text = listener.transcriber.transcribe(segment)
            print(f"You said: {text}")
        except sr.UnknownValueError:
            print("Could not understand")
```

## Documentation

See [examples/](examples/) for more usage patterns.

## Development

```bash
# Clone repository
git clone https://github.com/hipsterbrown/hearken.git
cd hearken

# Install with dev dependencies
uv sync --all-extras

# Run tests
pytest

# Run tests with coverage
pytest --cov=hearken --cov-report=term-missing

# Format code
black hearken/ tests/

# Type checking
mypy hearken/

# Linting
ruff check hearken/ tests/
```

## Roadmap

- ✅ v0.1: EnergyVAD, core pipeline
- ✅ v0.2: WebRTC VAD support
- ✅ v0.3: Silero VAD (neural network)
- v0.4: Async transcriber support

## License

Apache 2.0

## Contributing

Contributions welcome! Please open an issue or PR on GitHub.

## Credits

Created by Nick Hehr (@hipsterbrown)