A method of decreasing the effect of an interference sound is disclosed and includes the following the steps: receiving an input sound by a first microphone and a second microphone to respectively acquire a first sound signal and a second sound signal; determining and acquiring a plurality of sound source position data according to a phase difference between a plurality of sound frames of at least one position low-frequency sound signal of the first sound signal and a plurality of sound frames of at least one position low-frequency sound signal of the second sound signal; determining a probability that a main direction of the input sound is in accordance with a target orientation according to each of the sound source position data; and adjusting, according to the probability, the sound volume of low-frequency sound signals of the first sound signal and the second sound signal being outputted.