Dual channel laser audio monitoring system for interferometric vibration measurement on shiny reflecting surfaces or retro-reflecting surfaces comprising, I. a transducer unit with, a. an optical module placed inside the transducer unit, comprising photodetectors (2119 and 2120) each outputting an analog signal (2311 and 2312); b. a linear guide for adjusting the interval between two beam expander lens (1108 and 1109) assemblies; c. a bellows between the two beam expander lens assemblies (1108 and 1109); d. a signal level detection and indication block operating on the analog signals (2311 and 2312); II. a control unit with, e. a demodulation block comprising demodulators and operating on the analog signals (2311 and 2312) and outputting demodulated audio signals (3031 and 3032); f. an automatic volume control block operating on the demodulated audio signals; (3031 and 3032) and outputting audio signals (3041 and 3042); g. a graphical user interface for controlling the operation of the system; h. a filtering module comprising digital filters and operating on the two-channel signals (4101a and 4101b), which are the digitized versions of the audio signals (3041 and 3042), and outputting filtered channel signals (4103, 4104; 4105, 4106; 4108; 4109); III. a supporting system on which the transducer unit is placed; IV. an interface cable connected between the transducer unit and the control unit; V. speakers and/or stereo headphones for outputting the filtered channel signals (4103, 4104; 4105, 4106; 4108; 4109). I. a transducer unit with, a. an optical module placed inside the transducer unit, comprising photodetectors (2119 and 2120) each outputting an analog signal (2311 and 2312); b. a linear guide for adjusting the interval between two beam expander lens (1108 and 1109) assemblies; c. a bellows between the two beam expander lens assemblies (1108 and 1109); d. a signal level detection and indication block operating on the analog signals (2311 and 2312); a. an optical module placed inside the transducer unit, comprising photodetectors (2119 and 2120) each outputting an analog signal (2311 and 2312); b. a linear guide for adjusting the interval between two beam expander lens (1108 and 1109) assemblies; c. a bellows between the two beam expander lens assemblies (1108 and 1109); d. a signal level detection and indication block operating on the analog signals (2311 and 2312); II. a control unit with, e. a demodulation block comprising demodulators and operating on the analog signals (2311 and 2312) and outputting demodulated audio signals (3031 and 3032); f. an automatic volume control block operating on the demodulated audio signals; (3031 and 3032) and outputting audio signals (3041 and 3042); g. a graphical user interface for controlling the operation of the system; h. a filtering module comprising digital filters and operating on the two-channel signals (4101a and 4101b), which are the digitized versions of the audio signals (3041 and 3042), and outputting filtered channel signals (4103, 4104; 4105, 4106; 4108; 4109); e. a demodulation block comprising demodulators and operating on the analog signals (2311 and 2312) and outputting demodulated audio signals (3031 and 3032); f. an automatic volume control block operating on the demodulated audio signals; (3031 and 3032) and outputting audio signals (3041 and 3042); g. a graphical user interface for controlling the operation of the system; h. a filtering module comprising digital filters and operating on the two-channel signals (4101a and 4101b), which are the digitized versions of the audio signals (3041 and 3042), and outputting filtered channel signals (4103, 4104; 4105, 4106; 4108; 4109); III. a supporting system on which the transducer unit is placed; IV. an interface cable connected between the transducer unit and the control unit; V. speakers and/or stereo headphones for outputting the filtered channel signals (4103, 4104; 4105, 4106; 4108; 4109).