The present invention provides a technique whereby brain waves can be induced without imparting discomfort to a user. A sound output device 1 outputs a control sound for inducing brain waves. The sound output device 1 is provided with a sound collection unit 11 for collecting an environmental sound, a generating unit 12 for changing the phase and/or amplitude of the collected environmental sound so as to form the environmental sound and a beat sound having a predetermined frequency and generating the control sound, and an output unit 13 for outputting the generated control sound. The environmental sound is an operating sound of a machine or the like, for example. A program that the sound output device 1 causes a computer to execute includes a step for collecting the environmental sound, a step for changing the phase and/or amplitude of the collected environmental sound so as to form the environmental sound and a beat sound having a predetermined frequency and generating the control sound, and a step for outputting the generated control sound.
SOUND OUTPUT DEVICE, SOUND OUTPUT METHOD, AND PROGRAM