On/off volume control
This control turns the detector on or off, and controls the volume. It is not to be confused with the threshold, threshold controls the amount of audio tone given. This controls the volume. A good level is about 5 to 5 1/2. If you use the speaker, you may need to turn the volume to the max. If you use headphones, a good volume level is around 5, but varies to individual.
Other Help Topics
Here are some more help topics on the detector: