SOUND PROCESSING DEVICE, VEHICLE AND SOUND PROCESSING METHOD

A sound processing device includes: a sound source that outputs a common sound signal to a first speaker for a vehicle exterior and a second speaker for a vehicle interior that are mounted on the vehicle; a notification sound controller that outputs a signal corresponding to a notification sound for notifying an approach of the vehicle to the first speaker based on the sound signal output from the sound source; and an acceleration sound controller that outputs a signal corresponding to an acceleration sound of the vehicle to the second speaker based on the sound signal output from the sound source.