A signal processing apparatus for generating a playback audio signal to be played back together with a slow-motion image based on image capturing in a capturing target region, obtains a first audio signal containing a sound in the capturing target region, and based on sound acquisition in a first period shorter than a capturing period corresponding to the slow-motion image, obtains a second audio signal containing a sound in a peripheral region of the capturing target region, and based on sound acquisition in a second period longer than the capturing period, and synthesizes the first audio signal and the second audio signal, thereby generating the playback audio signal to be played back together with the slow-motion image.