Longer Speaker Enclosure
Apple has also given the 16-inch MacBook Pro a refresh in the speaker department, with significantly updated sound and recording quality. The new speaker system also includes a longer speaker enclosure with woofers on both the top and the bottom.
Why Apple decided to go with this design, it isn’t clear. The woofers are pretty clearly meant to cancel out each other’s vibration, and iFixit notes that they’ll likely also direct sound to improve the overall audio quality.