SOUND OUTPUT DEVICE

1 . A sound output device for masking an operation sound generated by equipment, comprising:

a sound reproducing unit that starts reproducing a masking sound before the operation sound is generated; and

a sound output unit that outputs the masking sound reproduced by the sound reproducing unit.

2 . The sound output device according to claim 1 , wherein after output of the masking sound starts, the sound reproducing unit gradually raises an output sound pressure level of the masking sound.

3 . The sound output device according to claim 1 , wherein,

the masking sound is pre-created so as to mask an operation sound generated during a predetermined action of the equipment, and

the sound reproducing unit controls the timing of starting output of the masking sound and the degree of change in output volume of the masking sound, on the basis of a period of time from the equipment starting operation until the predetermined action is performed.

4 . The sound output device according to claim 1 , wherein,

the masking sound is pre-created so as to mask an operation sound generated during a predetermined action of the equipment, and

the equipment performs the predetermined action after a lapse of a predetermined period of time once output of the masking sound starts.

5 . The sound output device according to claim 1 , wherein,

the masking sound is pre-created so as to mask an operation sound generated during a predetermined action of the equipment,

the sound reproducing unit constantly reproduces the masking sound at a relatively low sound pressure level, and

when the equipment starts operating, the sound reproducing unit reproduces the masking sound with the sound pressure level raised to a relatively high value before the predetermined action.

6 . The sound output device according to claim 1 , wherein the equipment is an image forming apparatus.