| 2426948 | Coaxial dual-unit electrodynamic loud-speaker | |||
| 2301459 | Electric megaphone | |||
| 2295483 | Loudspeaker | |||
| 2214591 | Signal translating apparatus | |||
| 2167625 | Speaker unit | |||
| 2077170 | Acoustic device | |||
| 2007747 | Acoustic apparatus | |||
| 1907723 | Sound reproducing device | |||
| 1759614 | Acoustic amplifier |
| GB442900A |