The LD-18 digital water leak detector from SubSurface Leak Detection significantly reduces ambient intermittent noises from dogs barking, cars and footsteps. The digital electronics sample sounds every few thousandths of a second, and if it hears an intermittent sound, it suppresses it instantly. Since water leak sounds are almost always continuous noises, the unit can identify these leak sounds even in difficult outdoor conditions. It is more sensitive than human hearing, and the user can let the amplifier pinpoint where the leak is located. The user can mark 10 spots directly over the pipe every couple of feet or more, and let the unit listen at each spot for 30 or 40 seconds. Store the sound loudness levels at the spots in the amplifier’s sound data file, and press “File” to see a graph of the loudness levels at all 10 spots. If one spot is louder, go back and re-listen for 60 to 90 seconds. If it is still the loudest, that’s where the leak is located. 775/298-2701; www.subsurfaceleak.com.