From the July 13, 1935, issue

SOUNDPROOFING GIVES WALL LOOK OF UNDERGROUND CAVE

The microphone shown on the front cover of this week’s Science News Letter is not broadcasting from among the stalactites of some underground cavern. The curious formations shown are nothing more romantic than cotton waste covering the walls and ceiling of a soundproof room in the General Electric Company’s general engineering laboratory at Schenectady, N.Y.