According to one embodiment, an apparatus for processing a voice signal includes a display configured to display an image of a user or a character corresponding to the user, a microphone, a speaker configured to output a voice signal of the user, a memory configured to store a trained voice age conversion model, and a processor configured to, based on changing an age of the user or the character displayed on the display, control the display such that the display displays the user or the character corresponding to the changed age. The processor is further configured to determine a first age that is a current age of the user or the character based on the voice signal of the user inputted through the microphone. Accordingly, convenience of a user may be enhanced.