| 3024309 | N/A | |||
| 2941044 | Controlled sound reproduction | |||
| 2872515 | Synthetic reverberation system | |||
| 2852604 | Sound reproduction apparatus | |||
| 2822429 | Plural control track system | |||
| 2748192 | Reverberation generator | |||
| 2714633 | Perspective sound systems | |||
| 2107804 | Method of modifying the acoustics of a room |
| BE564517A | ||||
| DE928351C |