Sirencide

• A. Phenomenon where EMS vehicles out run the sound waves of their electronic sirens (typically around 55mph)
• B. A phenomenon where EMS vehicles outrun the sound waves of their sirens
• C. A device used to measure siren sound levels
• D. A type of siren pattern

Answer: (A)

Sirencide is the phenomenon where an EMS vehicle’s speed reduces the effectiveness of its own siren’s warning. The siren emits sound that travels through the air at the speed of sound, but as the vehicle moves quickly, the expanding front of that sound can’t reliably reach oncoming pedestrians or other drivers ahead in time. In practice, once the vehicle reaches speeds around 55 mph, the audible cue from the siren ahead becomes less effective, increasing the chance that people won’t hear it early enough. That’s why warning emphasis shifts toward eyes-on driving, use of lights, and other cues rather than relying on the siren alone. This term isn’t about a device to measure siren levels or a particular siren pattern.