Kankakee Valley Post, Volume 12, Number 11, DeMotte, Jasper County, 22 January 1942 — 'Tin Ear’ [ARTICLE+ILLUSTRATION]

'Tin Ear’

TROY. N. Y.—Dr. Donald A. Wilbur of Rensselaer Polytechnic institute is shoun testing a sound detector hastily constructed in the institute's physics laboratory to determine how effectively such cheaply built devices might be adopted throughout the country by air raid spotters. A few boards, a phonograph horn. a microphone and a bat-tery-operated amplifier and ear phones are the ingredients of the del '( tor that can pick up the sound of bombers five to t('n miles distant .