How FireFLY LE III Improves Dispatch Accuracy and Officer Safety
In criminal cases involving alleged gunfire, the accuracy of location and timing data can shape the direction of an investigation—and, ultimately, the outcome of a case.
For defense attorneys, understanding how gunshot detection systems work—and where they can fail—is critical when evaluating the reliability of evidence presented by the prosecution.
One of the most important, and often overlooked, issues in acoustic gunshot detection is Event Association Error.
What Is Event Association Error?
Event Association Error occurs when a detection system cannot distinguish between two or more acoustic events that happen at nearly the same time.
In systems that rely on a single microphone per sensor, separate sounds may be incorrectly grouped together and treated as a single event.
This can lead to:
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Incorrect geolocation of the event
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Misclassification of non-gunfire sounds as gunfire
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Misattribution of where an incident actually occurred
In practical terms, a vehicle backfire and a firearm discharge occurring in different locations may be interpreted as one event—and mapped to the wrong place.
Why This Matters in Legal Proceedings
For defense attorneys, these errors raise important questions:
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Was the detected event accurately classified as gunfire?
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Was the reported location correct?
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Could multiple unrelated sounds have been merged into one event?
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What level of uncertainty exists in the system’s output?
If an acoustic system incorrectly associates events, it can influence:
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Initial police response location
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Witness canvassing and evidence collection
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Identification of suspects
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The narrative presented in court
Even small inaccuracies in location data can have significant implications when used to support timelines or place individuals at or near a scene.
The Limitation of Single-Microphone Systems
Legacy systems and some current technologies rely on a single microphone per sensor.
While capable of detecting loud acoustic events, these systems are limited in their ability to:
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Separate simultaneous sounds
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Determine precise direction of origin
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Accurately resolve multiple events occurring within the same time window
This limitation is the root cause of Event Association Error.
How FireFLY LE III Addresses the Issue
FireFLY LE III was designed to overcome this limitation through a multi-microphone array within each sensor, combined with advanced processing techniques.
Each sensor applies:
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Time of Arrival (TOA) analysis to measure when sound reaches each microphone
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Direction of Arrival (DOA) analysis to determine where the sound originated
Because sound waves reach each microphone at slightly different times depending on their origin, the system can:
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Distinguish between separate acoustic events
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Establish independent lines of bearing
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Accurately geolocate each event
Practical Impact on Evidence Reliability
With multi-microphone processing, FireFLY LE III can identify:
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A vehicle backfire and a firearm discharge as two distinct events
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The correct location of each event
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The true sequence and timing of events
For defense attorneys, this level of resolution provides:
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Greater confidence in the integrity of location data
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Reduced risk of misattribution
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Clearer insight into how acoustic evidence was generated
A More Reliable Foundation for Investigation
Acoustic gunshot detection is increasingly used to support investigative and prosecutorial decisions.
As its role grows, so does the importance of understanding the underlying technology and its limitations.
Systems that reduce Event Association Error offer:
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More accurate event reconstruction
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Stronger evidentiary reliability
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Greater transparency in how conclusions are reached
Why This Matters
At its core, the issue is not just about technology—it is about accuracy, fairness, and due process.
For defense attorneys, the ability to scrutinize how gunshot detection data is generated—and whether it can distinguish between simultaneous events—can be critical in assessing the strength of a case.
FireFLY LE III represents an advancement in addressing one of the key limitations in acoustic detection, helping ensure that when this type of evidence is used, it is grounded in more precise and reliable data.