A leakage listening detector with high performance and practicality is designed and developed based on the practical requirement from leakage detecting.Several functional parts such as JFET follower

high gain preamplifier

low pass filter and feedback circuit are integrated into the detector to both improve listening recognition and achieve a appreciable balance between listening recognition and noise suppression.Band pass filter（BPF） under the control of MCU can easily switch among the common-used frequency band.Simulation shows that the BPF meets the designed requirements.Test on the prototype detector indicates that the system operates excellently both in listening recognition and noise suppression

which completely satisfies the requirement specification.