Patent ID: 8712064

Claim:
A signal processing device comprising: an audio signal acquisition portion to acquire a stereo audio signal representing stereo audio content, the audio signal comprising a first audio signal and a second audio signal; an external signal acquisition portion to acquire a stereo external signal representing external sound obtained by collecting ambient sound, the stereo external signal comprising a first external signal and a second external signal; an output signal generation portion to generate, from the stereo audio signal acquired by the audio signal acquisition portion and the stereo external signal acquired by the external signal acquisition portion, a stereo output signal representing stereo audio provided to a user, the stereo output signal comprising a first output signal provided to the user from a first direction and a second output signal provided to the user from a second direction; a mode setting portion to set, as an operation mode of the output signal generation portion, at least an external mode; a direction specification portion to specify, when the external mode is set, a direction of an emission source of the external sound with respect to the user, based at least in part on the stereo external signal acquired by the external signal acquisition portion; and a fade control portion to control an operation to generate the stereo output signal by the output signal generation portion in accordance with the operation mode set by the mode setting portion and the direction of the emission source of the external sound specified by the direction specification portion, wherein: when the external mode is set and the direction of the emission source of the external sound is specified to correspond with the first direction, the fade control portion causes the output signal generation portion to generate the first output from at least the stereo external signal, and also to generate the second output signal from at least the stereo audio signal, and wherein when the external mode is set, the fade control portion causes the output signal generation portion to generate the first output signal from the stereo external signal only, and to generate the second output signal by converting the stereo audio signal to a monaural audio signal.