Evening Republican, Volume 23, Number 44, Rensselaer, Jasper County, 19 February 1920 — Anti-Noise Telephones. [ARTICLE]

Anti-Noise Telephones.

Edwin S. Pridham and Peter L. Jensen, engineers of San Francisco, solved the problem of telephoning in the midst of noise by simply “opening the diaphragm and button of the transmitter and letting all the noise in—impartially to both sides of the diaphragm. The result was entire exclusion from the circuit of every sound save the voices of the users. As one test of the new method an “anti-noise” telephone was placed inside the steel shell of a boiler. With several men outside the boiler pounding on the shell wit. hammers, a person inside was able to elephone to those on the outside without interference from the din of the hammering.