Differential frequency ultrasonic-based audio sound source generating method and system and testing method and system of features of airway

The invention discloses a differential frequency ultrasonic-based audio sound source generating method and system and a testing method and system of features of an airway. The generating system comprises a signal generating module, a signal amplifying module and low-frequency broadband ultrasonic probes; the signal generating module is used for generating two square-wave signals different in frequency; the signal amplifying module is used for amplifying the square-wave signals so as to improve drive voltage of the low-frequency broadband ultrasonic probes and enhance effective acoustic pressure and effective acoustic power of an audio sound source finally generated; the low-frequency broadband ultrasonic probes are driven by the amplified square-wave signals respectively so as to generate two different ultrasonic waves, thus generating the controllable frequency audio sound source under nonlinear interaction. The non-invasive audio sound source-based testing method of features of the airway includes: using the audio sound source generated via differential frequency ultrasonic as an input signal of the airway, measuring an audio output signal of an outlet end of the airway, and non-invasively measuring transmission features of the airway by means of signal frequency analysis.