3. The display apparatus as claimed in claim 1 , wherein the weak phonetic symbols include phonetic symbols for a specific pronunciation of which a frequency band or energy magnitude is decreased or lost by a surrounding environment, such that a recognition rate thereof is degraded.
1. A display apparatus comprising: an input unit configured to receive a user command; a display; and a processor configured to obtain a phonetic symbol for the user command, determine whether or not the user command is suitable for a registration based on the phonetic symbol, and control the display to display a visual indication based on a result of the determination, wherein the processor determines whether or not the user command is suitable for the registration, based on at least one of a total number of the phonetic symbol, whether or not vowels and consonants of the phonetic symbol is successive, a configuration form of the phonetic symbols, the number of phonetic symbol for each word, and whether or not a predetermined weak phonetic symbol is included in the phonetic symbol.