Leak Correlators listen to leak sounds through pipes rather than from above the ground.  Because of this they are unaffected by intermittent traffic and can locate leaks in situations where the leaks cannot be located by listening from above the ground.  TZE uses computerized leak correlators with 'Real-Time' capability, meaning that you locate the leak now and get results within minutes.  These locators also offer listen to leak sounds through the piping rather than through the soil.  They are generally unaffected by traffic noise and find leaks under difficult circumstances.