A method for input operation control, a terminal device, and an earphone are provided. The method includes the following. An input operation on an exhaust hole defined in an audio processing device is received. A frequency-response curve associated with an acoustic structure of the audio processing device is acquired according to an audio signal currently played by the audio processing device. The input operation is recognized according to the frequency-response curve, and a control instruction corresponding to the input operation is generated. A terminal device in communication with the audio processing device is controlled according to the control instruction.