A signal processing method includes: multiplying at least one of M signals output from M microphones by a gain so as to equalize sound pressure levels of the M signals, the M signals representing sounds that arrive at the M microphones from a sound source located within a predetermined distance from the M microphones, M being an integer equal to or greater than two; delaying at least one of the M signals so as to resolve time discrepancies between the M signals, the time discrepancies being caused by differences in arrival time between sounds that arrive at the M microphones from the sound source; and applying a filter so as to suppress a signal which is included in the M signals obtained through the multiplying and the delaying and which represents a sound output from the sound source located within the predetermined distance.