All modern smoke alarms, including the popular and inexpensive battery powered units available from Fire and Safety Centre have a test button that gives an audible alarm if the unit is operational. The most common reason for a test failure is an exhausted battery but clearly it would be mere chance to test at the moment the battery fails, which is why it is important to run a test every week. It is hardly a major chore to push a button.
We also recommend that irrespective of the test result that the battery is replaced once a year. A decent quality battery, (avoid the car boot rip off’s) will last at least a year.
A recent innovation that is also worth considering is a combined Smoke and Carbon Monoxide detector alarm. Also battery powered, the unit gives a loud verbal alarm message rather than a siren.
Carbon Monoxide is odourless and colourless so a detector is the first line of defence.
A smoke detector is really a must have in any home. If you burn hydrocarbon fuel of any kind a Carbon Monoxide is also a sensible added precaution.