11. This was in spite of some carbon microphones used, which had resonances that colored the recorded tone. 12. Including the quadruplex telegraph, the carbon microphone , phonograph, incandescent light bulb and system of electric lighting. 13. Alexander Graham Bell hired Blake and put him to work with Emile Berliner who also invented a carbon microphone . 14. Carbon microphones found use as early telephone repeaters, making long distance phone calls possible in the era before vacuum tubes.15. The first microphone that enabled proper voice telephony was the ( loose-contact ) carbon microphone ( then called transmitter ). 16. In 1878, David E . Hughes noticed that sparks could be heard in a telephone receiver when experimenting with his carbon microphone . 17. The passive hydrophones of the Imperial Japanese Navy were based on moving coil design, Rochelle salt piezo transducers, and carbon microphones . 18. He moved back to London in 1857 and further pursued experimentation and invention, coming up with an improved carbon microphone in 1878. 19. To pick up the programmes, multiple large carbon microphones were placed in the theatre footlights to pick up the sounds of the performers. 20. The frequency response of the carbon microphone , however, is limited to a narrow range, and the device produces significant electrical noise.
