The present disclosure generally relates to systems for maintaining a user's privacy in relation to mobile computing devices. In one general aspect a system includes an acoustically insulated housing, a speaker system, a touchscreen, and a control system. The housing has an interior sized to contain a mobile computing device. The speaker system includes a speaker arranged to direct sound into the interior volume. The control system is configured to perform operations that include causing the speaker system to emit voice obscuring noise into the interior volume of the housing, receiving display data indicating content displayed on a touchscreen of the mobile computing device, causing the touchscreen display to present the display data in a manner that substantially mirrors the content as displayed on the touchscreen of the mobile computing device, and providing control signals indicating user inputs received on the touchscreen to control functions of the mobile computing device.