Signal processing device, sound output device, and signal processing method

A signal processing method executed by a signal processing device, the method comprising:

• a masking determination process that determines a masking state of a content sound and an ambient sound on a basis of content sound data of multiple channels output from multiple sound output drivers disposed on a sound output device, ambient sound data obtained by multiple microphones disposed on the sound output device and each collecting the ambient sound, and information indicating an arrival direction of the ambient sound;
• and
• a sound processing control process that performs control associated with sound processing according to a determination result of the masking state obtained by the masking determination process.