This specification provides a terminal including a microphone that is configured to receive a user's voice input for controlling an operation of the terminal, an analyzing unit that is configured to sense a degree of proximity between the user's mouth and the microphone while the voice is input, an output unit that is configured to output at least one of visible data and audible data based on the voice, and a controller that is configured to restrict the output of the audible data when the degree of proximity is smaller than a preset range and a volume of the voice is below a preset reference volume.