A display apparatus , comprising: a user inputter configured to receive a user input; a content receiver configured to receive content data from a content source; a sound output configured to output sound included in the content data; and a processor configured to: collect a environment information when the content data is received from the content receiver, wherein the environment information includes sound characteristics of the content data, sound mode selected by the user through the user inputter , sound volume input by the user inputter , external noise collected by a microphone and viewing time calculated by using a timer, decode the content data into sound data, set a sound parameter corresponding the collected environment information, convert the sound data into a sound signal according to the set sound parameter, control the sound output to output the sound corresponding to the sound signal, receive the user input for at least one of a sound mode and a sound volume of the output sound, perform a reinforcement learning to modify the set sound parameter according to the received user input, obtain a first reward as a reward of the reinforcement learning when the user input is received, obtain a second reward greater than the first reward as the reward of the reinforcement learning when the user input is not received, and perform the reinforcement learning so that an accumulated reward obtained by accumulating the first reward or the second reward is maximized, each time the reinforcement learning is performed. a user inputter configured to receive a user input; a content receiver configured to receive content data from a content source; a sound output configured to output sound included in the content data; and a processor configured to: collect a environment information when the content data is received from the content receiver, wherein the environment information includes sound characteristics of the content data, sound mode selected by the user through the user inputter , sound volume input by the user inputter , external noise collected by a microphone and viewing time calculated by using a timer, decode the content data into sound data, set a sound parameter corresponding the collected environment information, convert the sound data into a sound signal according to the set sound parameter, control the sound output to output the sound corresponding to the sound signal, receive the user input for at least one of a sound mode and a sound volume of the output sound, perform a reinforcement learning to modify the set sound parameter according to the received user input, collect a environment information when the content data is received from the content receiver, wherein the environment information includes sound characteristics of the content data, sound mode selected by the user through the user inputter , sound volume input by the user inputter , external noise collected by a microphone and viewing time calculated by using a timer, decode the content data into sound data, set a sound parameter corresponding the collected environment information, convert the sound data into a sound signal according to the set sound parameter, control the sound output to output the sound corresponding to the sound signal, receive the user input for at least one of a sound mode and a sound volume of the output sound, perform a reinforcement learning to modify the set sound parameter according to the received user input, obtain a first reward as a reward of the reinforcement learning when the user input is received, obtain a second reward greater than the first reward as the reward of the reinforcement learning when the user input is not received, and perform the reinforcement learning so that an accumulated reward obtained by accumulating the first reward or the second reward is maximized, each time the reinforcement learning is performed. <EOS>