A method, comprising: constructing sound segments for a plurality of machines (104-1, 104-2, 104-3), the constructing comprising: obtaining an operation schedule for each of the plurality of machines (104-1, 104-2, 104-3); obtaining first sound signatures from a plurality of acoustic sensors for ones of the plurality of machines (104-1, 104-2, 104-3) operating during periods of time that the ones of the plurality of machines (104-1, 104-2, 104-3) are operating by itself as indicated by the operation schedule; associating the first sound signatures to ones of the plurality of machines (104-1, 104-2, 104-3) and an operation state as the sound segments for the ones of the plurality of machines (104-1, 104-2, 104-3); obtaining second sound signatures from the sensors during periods in which multiple ones of the machines are in overlapped operation; processing the second sound signatures based on the associated signatures to derive third sound signatures for overlapped ones of the plurality of machines (104-1, 104-2, 104-3) as the sound segments for the overlapped ones of the plurality of machines (104-1, 104-2, 104-3), characterized by the step of obtaining the operation schedule for the each of the plurality of machines (104-1, 104-2, 104-3) comprising obtaining the operation schedule from a server (100-2) managing the plurality of machines (104-1, 104-2, 104-3) on a factory floor through a plurality of programmable logic controllers (PLCs) . constructing sound segments for a plurality of machines (104-1, 104-2, 104-3), the constructing comprising: obtaining an operation schedule for each of the plurality of machines (104-1, 104-2, 104-3); obtaining first sound signatures from a plurality of acoustic sensors for ones of the plurality of machines (104-1, 104-2, 104-3) operating during periods of time that the ones of the plurality of machines (104-1, 104-2, 104-3) are operating by itself as indicated by the operation schedule; associating the first sound signatures to ones of the plurality of machines (104-1, 104-2, 104-3) and an operation state as the sound segments for the ones of the plurality of machines (104-1, 104-2, 104-3); obtaining second sound signatures from the sensors during periods in which multiple ones of the machines are in overlapped operation; processing the second sound signatures based on the associated signatures to derive third sound signatures for overlapped ones of the plurality of machines (104-1, 104-2, 104-3) as the sound segments for the overlapped ones of the plurality of machines (104-1, 104-2, 104-3), obtaining an operation schedule for each of the plurality of machines (104-1, 104-2, 104-3); obtaining first sound signatures from a plurality of acoustic sensors for ones of the plurality of machines (104-1, 104-2, 104-3) operating during periods of time that the ones of the plurality of machines (104-1, 104-2, 104-3) are operating by itself as indicated by the operation schedule; associating the first sound signatures to ones of the plurality of machines (104-1, 104-2, 104-3) and an operation state as the sound segments for the ones of the plurality of machines (104-1, 104-2, 104-3); obtaining second sound signatures from the sensors during periods in which multiple ones of the machines are in overlapped operation; processing the second sound signatures based on the associated signatures to derive third sound signatures for overlapped ones of the plurality of machines (104-1, 104-2, 104-3) as the sound segments for the overlapped ones of the plurality of machines (104-1, 104-2, 104-3), characterized by the step of obtaining the operation schedule for the each of the plurality of machines (104-1, 104-2, 104-3) comprising obtaining the operation schedule from a server (100-2) managing the plurality of machines (104-1, 104-2, 104-3) on a factory floor through a plurality of programmable logic controllers (PLCs) . <EOS>