Balanced armature drivers are often chosen for high fidelity earphones because of the wide frequency response and small size. Just as home speakers require more than one driver for high fidelity sound, the same is true for earphones. Balanced armature drivers are small enough to combine multiple units in a comfortable earphone. An earphone is a system comprised of the drivers, the mechanical design of the earphone housing, and other elements such as dampers and crossover circuits. This presentation will describe the different methods used to acoustically tune a balanced armature earphone to achieve the desired sound. Then the available driver models and characteristics will be shown.