Methodology

Analysis Methods

Transparency in methodology is non-negotiable. Every technique we use is documented here so our work can be scrutinized and replicated.

01

Time Difference of Arrival (TDOA)

When a sound event is captured by multiple recording devices at known positions, the time difference between arrivals constrains the source location to a hyperbolic curve. With three or more receivers, multilateration pinpoints the source position.

Applications: shooter localization, shot count verification, source separation
Tools: custom TDOA solver, Google Earth Pro (KML overlays), Praat, Audacity
02

Spectral Analysis

Fourier transform-based decomposition of audio signals into frequency components over time. Spectrograms reveal patterns invisible in the time domain — harmonics, formants, transient events, and compression artifacts all have distinct spectral signatures.

Applications: sound classification, editing detection, environmental characterization
Tools: Praat, Audacity, SoX, custom Python (scipy, librosa)
03

Impulse Response & Echo Analysis

Impulsive sounds (gunshots, claps, etc.) reveal the acoustic properties of the recording environment through their reflections. By analyzing the timing and amplitude of echoes, we can distinguish direct sounds from reflections — critical for accurate shot counting and source characterization.

Applications: shot counting, environment modeling, source/reflection separation
Tools: Praat, custom convolution analysis, RT60 measurement
04

Metadata & Codec Forensics

Audio file metadata (container format, codec parameters, encoding history) provides provenance information. Compression artifacts, re-encoding signatures, and container inconsistencies can reveal whether a file has been modified, re-encoded, or assembled from multiple sources.

Applications: authenticity verification, chain-of-custody analysis
Tools: MediaInfo, FFprobe, ExifTool, hex editors