United time-frequency analysis for background sounds of CVR

A cockpit voice recorder(CVR) in aircraft records many cockpit voices,such as speaker voices,noises,background sounds with special meanings.Cockpit voices' complexity exacerbates analysis difficulty,using traditional differentiating and hearing methods can not obtain cockpit voices' characteristics easily.In the light of the shortage in cockpit voice hearing and analysis using traditional short time Fourier transformation(STFT),the united time-frequency analysis was introduced into airplane cockpit voice analysis,as an expended CVR analysis method.Compared with the former methods,time-frequency distribution and its rearrangement dominated in time-frequency resolution and suppressing interference of cross terms,and were adapted to analyze non-stationary cockpit background sounds,as a valuable method for flight accident investigatations.