Distributed optical fiber perimeter security system, and sound restoration system and method

A distributed optical fiber perimeter security system, and sound restoration system and method. The sound restoration system is applied to the distributed optical fiber perimeter security system monitoring several protection areas. The sound restoration system comprises: a laser generation mechanism (11) for providing a laser signal; a beam splitting mechanism (12) for splitting the laser signal into multiple input optical signals; a plurality of optical fiber Michelson interferometer mechanisms (13) corresponding to each of the protection areas, wherein each of the optical fiber Michelson interferometer mechanisms (13) receives an input optical signal and outputs, in response to a surrounding sound pressure, an interference signal; and an audio output mechanism (14) for receiving the interference signal and when an alarm signal of any of the protection areas is received, outputting an audio signal restored according to the interference signal of the protection area. The system can help a user make a further confirmation and determination on an occurrence of abnormal events such as intrusions.