Plural portable devices, configured to produce special effect/s, responsive to a controller configured to provide instructions, on occasions separated by a time interval of t seconds, to transmitter/s, to transmit commands to the portable devices to produce a special effect at a time separated by S seconds from a first occasion, on which the devices receive from the controller commands to begin producing the special effect in S seconds. On a second occasion the devices receive from the controller commands to begin producing the special effect in (S-1) seconds, such that the plural devices produce the special effect synchronously and even devices which received only some of the commands transmitted, participate in production of special effects.

An audio output device and associated output method produce sound effects that are more natural to a listener are given to a piece of music. A mode is selected from a plurality of modes, and first sound source data and second sound source data are respectively outputted as the sound effects with music data at an output level that is determined based on the mode selected by a mode selection unit.