An information processing device comprising: a first acquisition unit that acquires biological information on a user acquired by a biological information acquisition device ; a first judgment execution unit that executes a first judgment on whether a first discomfort condition as a discomfort condition corresponding to the biological information is satisfied or not based on first discomfort condition information specifying the first discomfort condition and the biological information acquired by the first acquisition unit ; a second acquisition unit that acquires a sound signal outputted from a microphone; an acoustic feature detection unit that detects an acoustic feature based on the sound signal; a second judgment execution unit that executes a second judgment on whether a second discomfort condition as a discomfort condition corresponding to the acoustic feature is satisfied or not based on second discomfort condition information specifying the second discomfort condition and the acoustic feature detected by the acoustic feature detection unit ; and an output judgment unit that judges whether first masking sound should be outputted from a speaker or not based on a result of the first judgment and a result of the second judgment, characterized in that the output judgment unit judges that the first masking sound should be outputted from the speaker when the result of the first judgment indicates that the first discomfort condition is satisfied and the result of the second judgment indicates that the second discomfort condition is satisfied, wherein the output judgement unit judges that no masking sound should be outputted from the speaker or an already outputted masking sound from the speaker should not be changed, when the result of the first judgment indicates that the first discomfort condition is not satisfied or the result of the second judgment indicates that the second discomfort condition is not satisfied. a first acquisition unit that acquires biological information on a user acquired by a biological information acquisition device ; a first judgment execution unit that executes a first judgment on whether a first discomfort condition as a discomfort condition corresponding to the biological information is satisfied or not based on first discomfort condition information specifying the first discomfort condition and the biological information acquired by the first acquisition unit ; a second acquisition unit that acquires a sound signal outputted from a microphone; an acoustic feature detection unit that detects an acoustic feature based on the sound signal; a second judgment execution unit that executes a second judgment on whether a second discomfort condition as a discomfort condition corresponding to the acoustic feature is satisfied or not based on second discomfort condition information specifying the second discomfort condition and the acoustic feature detected by the acoustic feature detection unit ; and an output judgment unit that judges whether first masking sound should be outputted from a speaker or not based on a result of the first judgment and a result of the second judgment, characterized in that the output judgment unit judges that the first masking sound should be outputted from the speaker when the result of the first judgment indicates that the first discomfort condition is satisfied and the result of the second judgment indicates that the second discomfort condition is satisfied, wherein the output judgement unit judges that no masking sound should be outputted from the speaker or an already outputted masking sound from the speaker should not be changed, when the result of the first judgment indicates that the first discomfort condition is not satisfied or the result of the second judgment indicates that the second discomfort condition is not satisfied. <EOS>