| 2819342 | Monaural-binaural transmission of sound | |||
| 2437445 | Sound reverberating device | |||
| 2230836 | Electrical musical instrument | |||
| 2105318 | Synthetic reverberation system | |||
| 2017153 | Sound reproducing system | |||
| 1947621 | Reverberation circuit | |||
| 1877317 | Musical instrument | |||
| 1642040 | Public-address system |
| DE928351C |