Abstract: A real-time adaptive active noise cancellation method, an earphone, and a non-transitory computer-readable medium are provided. The method includes: obtaining a first transfer function from a feedforward microphone to a feedback microphone while ANC is deactivated; deriving a second transfer function from a speaker to the feedback microphone using the first transfer function while ANC is active; determining a current wearing state of the earphone based on a characteristic value from the second transfer function; and updating filter parameters based on the current wearing state. This includes adapting parameters of an IIR filter and subsequently updating parameters of an FIR filter using the adapted IIR parameters, the first transfer function, the second transfer function, and signals from the feedforward microphone.