A portable electronic device can include a housing defining an aperture and a display positioned in the aperture. The display and the housing can define an internal volume and a speaker assembly can be positioned in the internal volume. The speaker assembly can include a speaker enclosure sealed to the housing within the internal volume, the speaker enclosure and the housing defining a speaker volume, and a speaker module in fluid communication with the speaker volume, the speaker module including a diaphragm positioned at an aperture defined by the speaker volume, the diaphragm defining multiple ridges.