The Apple-designed high-excursion woofer is positioned at the top of the speaker facing upwards, creating a wide range of deep bass that surpasses any traditional speaker. A six-microphone array, along with an internal bass-EQ microphone, analyses and compensates for the effect of the room on the bass response, providing rich, consistent sound. And a powerful motor drives the diaphragm a remarkable 20 millimeters, so the bass shines through even when the volume is low.

Source: Apple