A display apparatus comprising: a display; one or more loudspeakers; a signal processor (110, 212) configured to process an image signal to generate an image to be displayed on the display and sound to be output from the one or more loudspeakers; a communication interface (120, 211) configured to communicate with one or more external display apparatuses (220, 230); and a controller (140, 216) configured to transmit sound processed by the signal processor to the one or more loudspeakers based on a preset output designation state, determine an image display mode wherein the image display mode refers to a divided and displayed state of an image with respect to the display apparatus and the one or more external display apparatuses (220, 230), and adjust the output designation state of the sound with respect to the one or more loudspeakers based on the determination; wherein the controller is further configured to monitor a change in the image display mode and adjust the output designation state of the sound to correspond to the changed image display mode; wherein the display apparatus further comprising a storage (130, 215) configured to store one or more image display modes that show the divided and displayed state of the image with regard to the display apparatus and the one or more external display apparatuses (220, 230), and information about a plurality of output designation states of the sound corresponding to each image display mode, wherein the controller (140, 216) is configured to determine the output designation state of the sound among the plurality of output designation states of the sound corresponding to the determination result of the image display mode from the storage (130, 215), and adjust the output designation state of the sound based on the determination; and in response to the information about the plurality of output designation states of the sound corresponding to the one image display mode being stored in the storage (130, 215), the plurality of output designation states of the sound are previously prioritized, and the controller (140, 216) is configured to select an output designation state of the sound based on the preset priority, in response to the information about the output designation state of the sound corresponding to the one image display mode being searched for in the storage (130, 215). a display; one or more loudspeakers; a signal processor (110, 212) configured to process an image signal to generate an image to be displayed on the display and sound to be output from the one or more loudspeakers; a communication interface (120, 211) configured to communicate with one or more external display apparatuses (220, 230); and a controller (140, 216) configured to transmit sound processed by the signal processor to the one or more loudspeakers based on a preset output designation state, determine an image display mode wherein the image display mode refers to a divided and displayed state of an image with respect to the display apparatus and the one or more external display apparatuses (220, 230), and adjust the output designation state of the sound with respect to the one or more loudspeakers based on the determination; wherein the controller is further configured to monitor a change in the image display mode and adjust the output designation state of the sound to correspond to the changed image display mode; wherein the display apparatus further comprising a storage (130, 215) configured to store one or more image display modes that show the divided and displayed state of the image with regard to the display apparatus and the one or more external display apparatuses (220, 230), and information about a plurality of output designation states of the sound corresponding to each image display mode, wherein the controller (140, 216) is configured to determine the output designation state of the sound among the plurality of output designation states of the sound corresponding to the determination result of the image display mode from the storage (130, 215), and adjust the output designation state of the sound based on the determination; and in response to the information about the plurality of output designation states of the sound corresponding to the one image display mode being stored in the storage (130, 215), the plurality of output designation states of the sound are previously prioritized, and the controller (140, 216) is configured to select an output designation state of the sound based on the preset priority, in response to the information about the output designation state of the sound corresponding to the one image display mode being searched for in the storage (130, 215).