for locating underground plumbing leaks for municipal work incorporates piezoelectric technology.

Unlike normal air microphones, piezoelect r ic microphones are almost completely insensitive to air vibrations but transduce only structure-borne sound.

But sensitivity alone is not the only important performance criteria. Most any device will be able to amplify a sound to the point that it can hurt the ears. What’s more important is hearing the right sound and distinguishing it from background noise. That’s where the other two important criteria come into play.

Frequency Range

Both pressurized underground plumbing leaks and static-shell leaks in the pool make noises in a wide range of frequencies depending on a variety of conditions.

Similar to instruments in an orchestra, different conditions produce different kinds of leaks and make characteristic sounds that a veteran leak detector can learn to identify. Although every leak is different, as general rule, underground plumbing leaks make sounds in the lower frequency ranges while static leaks in the shell of the pool are in the higher range. If your listening device doesn’t pick up sounds at the top or bottom of this range, you will be missing the fullness of the sound a leak makes or you may miss it altogether.

Filtering Capability

The final performance criteria, and what is considered to be the most important for swimming pool applications, is in filtering capability.

A listening device’s filter allows the user to specifically highlight (or eliminate) a specific range of sounds. Filtering is important because the devices are so sensitive that the user will likely hear other sounds around the pool (it always seems as though the nextdoor neighbor wants to mow their grass when you’re trying to find a leak!). The filter helps the user zero in on the leak sound without being distracted by the background noise.

Additionally, different ranges of sound behave differently underground or underwater. Low-frequency sounds travel much further than high-frequency sounds. By selecting high-frequency sounds once a leak sound has been identified, the frequency filter can help in pinpointing leaks to a small area.

Remember you can always call manufacturers and talk through the buying process or for technical help regarding a leak or leak-detection equipment.