How to Generate a Temporal 4 Tone on Your AV Notification Device

The required notification tone has evolved. Years ago, devices emitted a constant tone generated by bells. Then we moved to the standardized temporal 3 (T3) tone for general evacuation. But now we have CO requirements for supervisory conditions that require a temporal 4 (T4) tone.

However, many of the standard notification devices in the market don’t have a default temporal 4 tone setting, so what are you to do?

You may be happy to know that our SpectrAlert Advance horns, 4-wire horn strobes, and low frequency sounders can support a wide variety of tones – outside of temporal 3 (T3) and continuous – that can be synchronized!

Have you ever wondered about the coded audio setting on our devices? Here’s a picture, just in case you haven’t seen it:


The coded setting — which is located on the back of System Sensor’s SpectrAlert Advance horns, 4-wire horn strobes, and low frequency sounders — supports a variety of tones outside of T3 and continuous.

Fire alarm control systems that have approval for coded abilities can generate a wide variety of custom tones that our devices will accept, including temporal 4.

Consult with your system manufacturer for specific instructions, but in general this result is accomplished via panel programming. Many of the systems have a library of tones and T4 is a default setting. By setting the device to coded setting, it will follow the pattern sent from the fire alarm control system.

For example, let’s look at a new sleeping space that requires the low frequency tone for both smoke and CO. The fire alarm control panel can be programmed to generate a temporal 4 alarm tone when the carbon monoxide detector goes into an alarm state, sent as a supervisory signal to the system, and then switch to temporal 3 alarm tone when the smoke detector goes into alarm. Now you have met two alarm condition requirements: smoke (T3) and CO (T4) – all while complying with the new low frequency requirements from one device. It’s really that easy.

Have you ever used the coded setting on your System Sensor AV devices? Leave us a comment below. We’d love to hear from you.

If you have any questions about generating a temporal 4 tone on your AV device, please contact our Technical Services department. You can reach them by phone at (800) 736-7672, or submit your question online. They’re available from 7:30 AM to 5:00 PM (Central), Monday through Friday. For after hours calls, please leave a message and your call will be returned as soon as possible on the next business day.

To find out more about AV notification devices from System Sensor, visit our website.

Are you interested in low frequency? Curious about CO or low frequency code adoption in your area? Check out our recently updated State Code Adoption Map! There’s information about statewide, local, and county adoption for low frequency, plus commercial CO legislation and and low frequency adoption.


Please note: According to UL, a temporal 4-tone pattern consists of 4 spaced tones, followed by a 5-second silent period that repeats for at least 4 minutes. After 4 minutes, the 5-second silent period can increase to 60 seconds. After that, the alarm signal repeats until the alarm resents or it’s manually silenced. 


About Rebecca Peterson

Rebecca Peterson is a Senior Product Marketing Manager for the AV business unit of System Sensor. Rebecca has been with System Sensor for 13 years and her primary focus is designing products that customers need and want.​

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