Scientific Architecture
Table of contents
- Bioacoustic Analysis Architecture
Bioacoustic Analysis Architecture
Overview
iNatSpectro implements research-grade bioacoustic analysis using standardized digital signal processing techniques. This architecture ensures reproducible results suitable for scientific research while maintaining real-time performance in web browsers.
Analysis Pipeline
Audio Processing Workflow
Audio Input → Digital Signal Processing → Frequency Analysis → Scientific Visualization
↓
Sample Rate Detection → FFT Analysis → Statistical Processing → Color Mapping
↓
Species-Specific Optimization → Dynamic Range Adjustment → Final Display
Core Scientific Components
1. Digital Signal Processing
- Sample Rate Preservation: Maintains original recording quality up to 384kHz for ultrasonic analysis
- FFT Analysis: Fast Fourier Transform with configurable window sizes (256-4096 samples)
- Overlap Processing: 50-75% window overlap for optimal temporal resolution
- Window Function: Hann window to minimize spectral leakage artifacts
2. Frequency Analysis
- Adaptive Frequency Range: Automatically adjusts to audio sample rate capabilities
- Logarithmic Scaling: Biologically relevant frequency display matching human auditory perception
- Nyquist Frequency Handling: Proper bandwidth limiting to prevent aliasing artifacts
- Species-Specific Ranges: Optimized frequency bounds for different taxonomic groups
3. Statistical Processing
- Percentile-Based Dynamic Range: Adaptive scaling based on signal strength distribution
- Noise Floor Estimation: Automatic background noise detection and compensation
- Gamma Correction: Non-linear brightness adjustment for enhanced pattern visibility
- Temporal Smoothing: Optional averaging to reduce noise while preserving biological signals
Species-Specific Optimization
Taxonomic Parameter Sets
iNatSpectro automatically applies research-validated parameter sets based on the taxonomic classification of observations:
Birds (Class Aves)
- Frequency Range: 100 Hz - 12 kHz (typical avian vocal range)
- Window Size: 1024 samples (good frequency resolution for song analysis)
- Temporal Resolution: Balanced for both calls and songs
Bats (Order Chiroptera)
- Frequency Range: 15 kHz - 120 kHz (ultrasonic echolocation)
- Window Size: 1024 samples (high frequency resolution)
- Dynamic Range: Enhanced sensitivity for faint echolocation calls
Frogs (Order Anura)
- Frequency Range: 150 Hz - 3 kHz (anuran call fundamentals)
- Enhanced Gamma: Optimized for low-frequency calls in noisy environments
Insects (Class Insecta)
- Frequency Range: 1 kHz - 20 kHz (chirping and stridulation)
- Fast Window: 256 samples for rapid temporal changes
Cetaceans (Infraorder Cetacea)
- Frequency Range: 20 Hz - 24 kHz (wide range from clicks to songs)
- Large Window: 4096 samples for detailed frequency analysis
- Extended Smoothing: Compensation for distant recordings
Visualization Methods
Scientific Color Mapping
- Viridis Colormap: Perceptually uniform scientific standard
- Intensity Representation: Accurate mapping of signal strength to visual brightness
- Dynamic Range Control: User-adjustable contrast for different recording conditions
Resolution and Display
- Configurable Resolution: 50-800 pixels per second temporal resolution
- High-Resolution Rendering: Detailed analysis for zoomed regions
- Performance Optimization: Automatic adjustment for long recordings
Interactive Features
- Real-Time Parameter Adjustment: Live updating of analysis parameters
- Zoom and Pan: Detailed examination of temporal and frequency features
- Measurement Tools: Accurate time and frequency readings
Quality Assurance
Validation Methods
- Reference Standards: Results validated against established bioacoustic analysis tools
- Reproducibility: Identical parameters produce identical spectrograms
- Cross-Platform Consistency: Same results across different browsers and systems
- Scientific Accuracy: Analysis methods follow published research standards
Accuracy Considerations
- Sample Rate Preservation: No frequency aliasing from downsampling
- Window Function: Hann window minimizes spectral leakage artifacts
- Dynamic Range: Percentile-based methods adapt to recording conditions
- Color Representation: Scientific colormap ensures accurate intensity perception
Limitations and Considerations
- Browser Constraints: Limited by Web Audio API capabilities
- File Size: Large audio files may require reduced resolution for performance
- Audio Quality: Analysis quality depends on original recording quality
Integration with iNaturalist
Data Access
- Read-Only: Extension only reads publicly available observation data
- Privacy Preserving: No user data collected or transmitted
- Local Processing: All analysis occurs within the user’s browser
Automatic Species Detection
- Taxonomic Lookup: Retrieves species information from observation metadata
- Profile Selection: Automatically applies appropriate analysis parameters
- Manual Override: Users can select alternative profiles when needed
Research Applications
- Reproducible Analysis: Consistent methodology enables comparative studies
- Parameter Documentation: All settings can be recorded for scientific publication
- Quality Metrics: Analysis parameters preserved with results
Future Technical Directions
Planned Enhancements
- Advanced Filters: Bandpass and notch filtering options
- Measurement Tools: Frequency and time cursors for precise measurements
- Export Capabilities: High-resolution image and data export options
Research Applications
- Automated Detection: Machine learning integration for call detection
- Pattern Recognition: Automated species identification assistance
- Comparative Analysis: Tools for multi-observation comparison
- Data Integration: Export formats compatible with research software
This architecture implements published bioacoustic analysis methods suitable for scientific research and education.