An audio signal processing method implemented by an audio system with an audio sensor and a speaker unit includes: measuring, by the audio sensor, acoustic signals reaching the audio sensor, producing a sensor audio signal; retrieving a speaker audio signal corresponding to a speaker acoustic signal from the speaker unit while measuring the acoustic signals reaching the audio sensor to produce the sensor audio signal; converting the speaker and sensor audio signals to speaker and sensor audio spectra; estimating, based on the speaker audio spectrum, an echo audio spectrum of an echo audio signal caused by the speaker acoustic signal in the sensor audio signal; computing, based on the echo audio spectrum and the sensor audio spectrum, echo suppression gains to be applied to the sensor audio spectrum, by using a MMSE-LSA estimator; and applying the echo suppression gains to the sensor audio spectrum.