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Audio Analysis

Speed from Audio

A video, security, dash, or body worn camera recording that shows nothing useful visually may still have captured critical audio information. Tire tread frequency varies with speed, and braking, turn signals, horns, and warning chimes all leave a signature.

Cameras on tripods set up at a roadside

Our experts developed and validated the method for determining vehicle speed from dash camera audio, first for passenger vehicles and then — with a modified tire equation accounting for commercial tread construction — for heavy trucks. All three papers went through SAE's peer review process.

That work makes speed determination possible in cases where the video is too dark, too compressed, or too poorly framed to support photogrammetry, and it provides an independent check where photogrammetry is available.

Beyond speed, audio establishes the timing of discrete events: the initiation of hard braking, turn signal activation, and horn use.

Audio can also be used to analyze bullet trajectory, sequencing of shots fired, ammunition type, or other events recorded on a body worn camera.

Scope

What this covers

Speed determination

  • Passenger vehicle tire tread frequency analysis
  • Commercial vehicle tire tread frequency analysis
  • Speed from roadway features such as expansion joints and rumble strips
  • Speed of e-bikes, scooters, motorcycles, electric motorcycles, trucks, buses, passenger cars, bicycles and more
  • Body worn camera audio can be analyzed for use of force, bullet trajectory and sequencing or other timing or event analysis
  • Validation against GPS and EDR ground truth

Event characterization

  • Hard braking
  • Turn signal and horn activation
  • Impact timing and sequence
  • Noise reduction and frequency isolation
  • Shots fired
  • Casings dropping on the ground
  • Reloadings and slide racking

Gallery

Video

Wheel Frequency To Speed

Peer-reviewed research

Published work behind this practice area

Authored by our experts and peer-reviewed by external experts.

All publications

Who does this work

Experts on this practice area

Henry V. Vega

PE, ACTAR

Accident reconstruction and audio analysis

  • Accident reconstruction, commercial and passenger vehicles
  • Audio analysis and speed determination
  • Photogrammetry, digital mapping, and video analysis
  • UAS scene capture and 3D simulation

6 publications

Justin Ngo

PE, ACTAR

Accident reconstruction, human factors, and vehicle testing

  • Heavy truck and passenger vehicle reconstruction
  • Human factors: perception, attention, and response
  • Premise slip, trip, and fall analysis
  • Vehicle testing, instrumentation, and data analysis

4 publications

Ziad Hatab

EIT, ACTAR

Accident reconstruction and vehicle systems

  • Accident reconstruction
  • Passenger Vehicle EDR Data
  • Heavy vehicle EDR Data
  • 3D modeling and simulation

2 publications

Request a case review

Send us the incident location, the date, and what is in dispute. We'll discuss what analysis is possible with the evidence that exists, and what it would take to get.