An audio engineer works on the recording, manipulation, mixing, reproduction, and reinforcement of sound. Audio engineers work on the "...technical aspect of recording—the placing of microphones, the turning of pre-amp knobs, the setting of levels. The physical recording of any project is done by an engineer ... the nuts and bolts." Many audio engineers creatively use technologies to produce sound for film, radio, television, music, electronic products and computer games. Audio engineers also set up and operate sound reinforcement systems for concert, corporate, theatre, sporting and other events.