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Gunshot Detection System

A real-time audio classification pipeline for detecting gunshots in urban environments, with mobile app integration for instant community alerts.

The Challenge

Community safety in urban environments requires rapid detection and response to gunshot incidents. Traditional methods rely on human reporting, which introduces delays and inconsistency.

An automated system needs to be fast, accurate, and respect privacy while providing actionable alerts to community members and authorities.

Constraints

  • Sub-second detection latency for immediate alerting
  • High precision to minimize false alarms
  • Privacy-preserving (no voice/conversation recording)
  • Edge inference for reduced bandwidth and privacy
  • Battery-efficient mobile deployment

Solution Architecture

Gunshot Detection Pipeline
1
Audio Capture Layer
Continuous audio stream (16kHz)
Background noise filtering
Trigger detection (amplitude spike)
2
Feature Extraction
Mel-spectrogram computation
MFCC extraction
Temporal feature aggregation
3
Classification (Edge Inference)
CNN classifier (quantized TFLite)
Confidence thresholding
Temporal smoothing
4
Alert System
Push notification dispatch
Location anonymization
Authority notification pipeline

Implementation Details

Audio Classification Model

CNN trained on curated acoustic datasets including gunshots, fireworks, car backfires, and urban noise. Transfer learning from audio classification backbone.

Edge Deployment

Model quantized to INT8 for TensorFlow Lite, enabling on-device inference with <50ms latency and minimal battery impact.

Privacy Architecture

All audio processing happens on-device. Only detection events (no audio) are transmitted. Location data is anonymized to neighborhood level.

False Positive Reduction

Multi-stage filtering: amplitude trigger, model confidence threshold, temporal smoothing, and location correlation to reduce alerts from similar but benign sounds.

Results

<500ms

End-to-end detection latency

94%

True positive rate

<2%

False positive rate

The system was designed with community input and deployed with full transparency about what data is collected and how it's used. Privacy-by-design was a core requirement, not an afterthought.

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