WhichBeep

Smoke & carbon monoxide detector finder

We'll tell you which one it actually is.

You've been guessing: kitchen, hallway, kitchen. We'll tell you which one it actually is.

Your phone's mic doesn't tilt its head. It just measures.

No app. No sign-up. Nothing leaves your phone.

How it works

  1. 1Name your locations — bedroom, hallway, kitchen.
  2. 2Walk to each one. Wait for the chirp.
  3. 3We rank them by volume and name the culprit.

Why are smoke and CO detector chirps so hard to find?

Smoke and CO detectors chirp at 2,500–4,500 Hz — a frequency your ears literally can't locate. The sound bounces off walls, ceilings, anything hard. That's why you're standing in the hallway at 2 AM tilting your head.

You're not imagining it. Your phone's mic doesn't tilt its head. It just measures.

What do the chirp patterns mean?

1 chirp / 30–60sLow battery. Replace it.
3 chirpsEnd-of-life warning. Replace the detector.
5 chirpsSealed 10-year unit is done. Replace the detector.
ContinuousReal alarm. Check for smoke or CO now.
CO emergency: A CO detector that beeps 4 times, pauses, and repeats is signaling carbon monoxide — not a low battery. Open windows, get everyone outside, call 911.

Questions or feedback? hello@whichbeep.com

WhichBeep is not a substitute for regular smoke detector maintenance. Test your detectors monthly and replace batteries at least once a year.

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