A method includes: generating a first and second shift signal by using a phase of a sound signal regarding an M-channel or a S-channel, the sound signal of the M-channel and the sound signal of the S-channel being obtained by using a mid-side microphone, the sound signal of the S-channel including a positive channel and a negative channel, the first shift signal being configured to reduce a phase difference caused by a difference between a sound arrival distance to the M-channel and a sound arrival distance to the positive channel of the S-channel, the second shift signal being configured to reduce a phase difference caused by a difference between the sound arrival distance to the M-channel and a sound arrival distance to the negative channel of the S-channel; and approximately converting the first or second shift signal into an L-channel signal and an R-channel signal of an XY-microphone.