ACA SuperBanshee | Full Alert | Johnson Creek, WI | Jefferson Co. Siren Test | Oct 2, 2024

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Did... not... wear... adequate... hearing protection...

Fun Facts:

Siren: Alerting Communicators of America three-signal SuperBanshee
Signal(s): Full Alert
Location: Johnson Creek Fire Department
Local Municipality: Johnson Creek
County: Jefferson County, Wisconsin
Date Recorded: October 2nd, 2024
Testing Time(s): Jefferson County tests their sirens on the 1st Wednesday of every month at 11:00 AM, weather permitting
Time of Activation: 11:05 AM
Distance from Pole: ~110 feet
Maximum Recorded SPL (@ ~110ft): 116.3 dBA (~119 dBC @ 584Hz [avg. of 463Hz & 705Hz])
Main Shot Video & Audio: iPhone 11 Pro
Other Sirens Heard: N/A
Enthusiasts Present: N/A

(in)FAQ:

Q: Why did I measure sound pressure level in dBA?
A: I measured the SPL of this siren using A-weighted decibels because, although dBA is more representative of human hearing, and the purpose of a siren is to be heard by humans, at the time of recording, I did not know that C-weighted decibels are actually the more appropriate unit of measure to measure peak volume levels of very loud sounds (that and dBC appears to be the industry standard for sirens anyway).

Q: How did I convert dBA to dBC?
A: Step 1: Perform a spectrum analysis on the recorded audio to determine the prominent frequencies. Step 1.5: If it's a dual tone siren, take the average of the two frequencies. Step 2: Plug that frequency into a weighting filter differentiator (by Sengpielaudio) to calculate the difference between dBA and dBC at that frequency. Step 3: Add the difference to the original measurement in dBA to get a rough estimate in dBC. For simplicity's sake, and more importantly, my sanity, any prominent harmonics and/or overtones were ignored for this process. This is by no stretch of the imagination a scientific process, but it should produce conversions that are "close enough".

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