The noise threshold for the sign is set using a dial on the back. It can be adjusted in 5 dB steps. The yellow lights come on 5 dB before the threshold is reached and the red lights come on at the threshold point.

As we are dealing with the human perception of noise levels the most suitable threshold level depends on many issues, such as the type of room and the general background noise.

Trial and Error

Often the best way, although not so scientific. Set the sign to around 55 dB and hang it on its mount. It will soon become apparent whether the selected level is too low (the sign lights up unnecessarily) or too high (the sign does not light up when the noise levels are high).

Adjust the level until an acceptable control level is found, so that the sign lights up only when the noise levels are genuinely too high.

Using a Noise Meter

If you have a Noise Meter then it can help when setting up the noise signs. Making some quick measurements will indicate the general noise level in an area in decibels - dB. This will help you choose the threshold level for the sign.

Even after setting up using a noise meter, you may want to make some adjustments to the threshold level over time to ensure the setting meets with the patient's perception of high noise levels.