An electronic device may include a housing having an audio output port therein, a display carried by the housing, and an internal partition carried within the housing and defining a baffle space behind at least a portion of the display. The electronic device may also include an audio output transducer carried by the internal partition and acoustically coupled to the audio output port, and a passive radiator within the baffle space, acoustically coupled between the audio output transducer and the display, and acoustically isolated from the audio output port.