The present disclosure relates to an audio signal processing method implemented by an audio system which includes at least an internal sensor, wherein the audio signal processing method includes: measuring, by the internal sensor, a voice signal emitted by the user which propagates via bone-conduction to the internal sensor, thereby producing a bone-conducted audio signal; processing the bone-conducted audio signal by a machine learning model, wherein the machine learning model is previously trained to produce a predicted air-conducted audio signal which corresponds to a prediction of an audio signal that would be produced by measuring the same voice signal propagating via air-conduction to a microphone, by increasing a spectral bandwidth of the bone-conducted audio signal and/or by reshaping a spectrum of the bone-conducted audio signal; and producing an internal signal for the internal sensor based on the predicted air-conducted audio signal.