A method includes acquiring sound signals of a current frame using two microphones, calculating an interaural level difference between the two microphones based on the sound signals of the current frame according to a first preset algorithm, determining whether the interaural level difference satisfies a sound source direction determining condition, determining, based on the interaural level difference, whether the sound signals of the current frame include a backward sound signal if the determining condition is satisfied, filtering out the backward sound signal from the sound signals of the current frame.