A speaker apparatus includes a speaker and a sound box. The sound box is shaped like a wine barrel and includes arced side boards and parallel top and bottom boards coupled to upper and lower ends of the side boards, respectively. The sound box is divided by at least an isolating board into air chambers interconnected with one another via at least an air aperture formed in the isolating board, and at least an air venting hole is formed through at least one of the side boards so as to communicate the air chambers with the outside. The speaker is installed on the top board via an installation hole formed therein. The interconnected air chambers and side boards produce air cushions corresponding to resonant frequency sections of the speaker, thereby enabling the speaker to reproduce original audio sounds without interfering with a successively formed air cushion.