[Problem] In the case where an audio signal of the same source is output from a plurality of speakers, the speakers are adjusted so that the audio signals become optimal at a listening position. [Solution] Processing in which an audio signal output from a wireless speaker 1 is collected by a microphone of a controller 2 carried by a listener and a delay time is measured that is the difference between an output time of the audio signal from the wireless speaker 1 and an input time of the audio signal to the microphone of the controller 2 is performed on a plurality of the wireless speakers 1 that output an audio signal of the same source, and the delay times of the audio signals from these respective wireless speakers 1 are measured. Output timings of these respective wireless speakers 1 are adjusted on the basis of these delay times.