Head-worn computers include a front frame mechanically adapted to secure a see-through computer display and an arm, secured to the front frame, mechanically adapted to secure the front frame to a head of a user. The arm includes an internal speaker system, enclosed by the arm, wherein the internal speaker system comprises a speaker having a first side and an opposing second side and a first cavity positioned along the first side of the speaker, the arm further comprising a vent positioned to vent the first cavity and a second cavity positioned along the second side of the speaker.