@jobrodie: Knowing this sound could save your life - it means replace the battery. If you hear this sporadic chirruping every 40 seconds then it's very likely that the battery in your smoke alarm needs replacing. It will continue to beep like that for some time before it falls silent as the battery dies. It's recommended that you check the battery is working periodically by pressing the 'PRESS' button to cause the alarm to emit a sound. If it emits a loud sound then all is well, if not, replace the battery. But if you hear this sound replace the battery too. Please tell your pals. I seem to be forever in small shops with intermittently beeping smoke alarms and at least a couple of the shops have told me that it means their smoke alarm is working. It really doesn't. I can see the logic in thinking that (for example medical equipment that beeps to let you know it's working) but it's absolutely not the case here. I don't want you to die of smoke inhalation :) #safety #smokealarm #smokealarmfail #thingstobeawareof #fire #smokedetector #smokedetectortest #smokedetectorcheck #batteries