"When a person speaks into the transmitter, the pulsations of the air, produced by the voice, produce the slight vibrations of the diaphragm...and these vary the pressure of the platinum point on the carbon disk, and these vary the strength of the electric current, and reproduce precisely similar vibrations in the diaphragm of the receiver, at the opposite end of the line, which reproduce the spoken words." -Atkinson 1903

Electric Telephone

"When a person speaks into the transmitter, the pulsations of the air, produced by the voice, produce…