This application provides a speaker apparatus includes: a speaker sound emission unit that includes a speaker diaphragm and configured to convert an electrical signal into a sound signal by using the speaker diaphragm; a horn includes a sound inlet and a sound outlet, the speaker sound emission unit is disposed on the sound inlet, and the horn is configured to amplify the sound signal and then propagate an amplified sound signal through the sound outlet; and a phase plug, configured to adjust a phase and/or an amplitude of the sound signal from the sound inlet; where relative locations of the speaker diaphragm and the phase plug remain unchanged to form an incompressible air cavity.