TDOA (Time Difference of Arrival)
Definition
The difference in arrival time of a sound at two spatially separated receivers. Each measured TDOA constrains the sound source to lie on a hyperbola in 2D (or hyperboloid in 3D). The intersection of hyperbolas from multiple sensor pairs localises the source.
- What it measures
- The time delay between when an acoustic event arrives at spatially separated sensors
- Primary application
- Gunshot localization in multi-microphone detection networks
- Geometric basis
- Hyperbola in 2D, hyperboloid in 3D
Common questions
How does TDOA pinpoint where a gunshot came from?+
Each pair of microphones records the sound at slightly different times. That time difference constrains the source to lie somewhere on a hyperbolic curve. When you combine measurements from multiple sensor pairs, their hyperbolas intersect at a single point: the source location.
Why is a hyperbola the shape used for TDOA localization?+
The difference in arrival time is fixed for any point on a hyperbola. If the source is close to one microphone, sound arrives there first. As you move points along the curve, the time difference stays constant, forming a hyperbola in 2D space or a hyperboloid in 3D.
Can TDOA work with just two microphones?+
Two microphones give one hyperbola, which narrows the location to a curve but not a point. Multiple sensor pairs are needed so their hyperbolas intersect at a precise location.
Related terms
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Explained in these topics
- Forensic Acoustics and Gunshot Acoustic AnalysisThe difference in arrival time of the same acoustic event at two spatially separated sensors; forms the basis of hyperbolic localisation in multi-microphone gu...
- Gunshot and Event Audio AnalysisThe difference in arrival time of a sound at two spatially separated receivers. Each measured TDOA constrains the sound source to lie on a hyperbola in 2D (or...