Sound Recording and reproducing 12 Light 10 Physics 8 Optics 7 Crystals 6 Digital techniques 6 Magnetic recorders and recording 6 Scattering 6 Visual perception 6 Heat 5 Radio 5 Digital video 4 Equipment and supplies 4 Music 4 Radio stations 4 Signal processing 4 Sound studios 4 Digital audiotape recorders and recording 3 Hearing 3 Image processing 3 Radio broadcasting 3 Speech processing systems 3 Standards 3 Arts 2 Engineering 2 Listening 2 MUSIC / Recording & Reproduction 2 Magnetism 2 Mechanics 2