A stethoscope is used to locate abnormal vibration or fluid leaks (valves, rings, seals, etc.). It helps identify hard-to-find noises, knocks and other disturbing sounds. It is used to control the operation of mechanisms and allows to localize possible damage by local monitoring of the components under inspection. Sound amplification helps to locate the fault. A stethoscope is used to detect mechanical damage such as in the engine, gearbox, bearings, etc.