FR660570A
(en )
1929-07-12
Acoustic device
FR32649E
(en )
1928-02-14
Electro-dynamic device that can be used as microphone or speaker
DK43461C
(en )
1930-12-08
Device for Telephone Devices with Speaker and Highly Sensitive Microphone.
FR661954A
(en )
1929-08-01
Ejectrocapillary device functioning as microphone, telephone and detector
FR699527A
(en )
1931-02-16
Device for disinfecting microphones and telephone headphones
DK42173C
(en )
1930-05-05
Vibration device for Microphones, Speakers and similar Devices.
FR652350A
(en )
1929-03-07
Key and clamping device
DK35869C
(en )
1926-04-12
Earpiece for Telephones and similar Devices.
FR639302A
(en )
1928-06-19
Speaker device
FR667002A
(en )
1929-10-09
Microphone
FR601399A
(en )
1926-03-01
Electrostatic telephone, microphone and especially loudspeaker
DK43097C
(en )
1930-10-06
Device for electrical vibration devices, in particular for the recording and reproduction of sound.
DK38857C
(en )
1928-06-11
Device for terminating telephone cables and the like.
FR624491A
(en )
1927-07-19
microphone earpiece
ES106498A1
(en )
1928-05-16
An phonographic impression phone device.
DK38669C
(en )
1928-04-16
Telephone (Speaker), Microphone or similar Device.
FR36028E
(en )
1930-04-01
Loudspeaker enhancements
FR682427A
(en )
1930-05-27
Loudspeaker enhancements
FR679871A
(en )
1930-04-18
Loudspeaker enhancements
DK33650C
(en )
1924-09-08
Device for Gramophones and similar Voice Devices.
FR695592A
(en )
1930-12-18
Acoustic device for loudspeakers
FR672063A
(en )
1929-12-23
Loud speaker
FR660970A
(en )
1929-07-19
Loud speaker
FR648477A
(en )
1928-12-10
Loud speaker
ES94935A1
(en )
1926-01-01
Installation in microphone and telephone devices.