Mechanical Listening Device (MLD)
Also known as listening sticks
Since the process of leak detection began operators have listened for the sound of water escaping from the pipe using mechanical devices. Traditional listening sticks for detecting water leaks rely on only one of the user's senses, hearing. This means that the experience and skill of the operator is paramount and, at best, users are only ever able to detect leaks that produce loud noises.
However, not all leaks produce a noise audible to the human ear. Contrary to common perception it is not always the largest leaks which are the loudest; often a large split in a water pipe will produce a less clear noise than a small hole. For this reason, amplifying the noise with an electro-acoustic microphone is becoming increasingly important to find leaks particularly in networks where these materials are increasingly used.
Modern electronics, therefore, provide the benefits of advanced sensor technology amplification and filtering to undertake this operation more effectively.
Electronic ground microphones and listening sticks are designed to amplify the noise generated by water escaping from buried supply pipes under pressure. They are particularly useful to confirm the precise location of a leak following a correlation and prior to digging.