Low-frequency sound generation - as obscuring noise for large offices,using polystyrene foam diaphragm

摘要

Broad-spectrum "infrasound" in the lowest audible range prevents conversations being audible at a distance in large offices divided by man-height partitions. A broad-spectrum noise voltage is low-pass filtered to 100 Hz, amplified, and radiated from pref. an electromagnetic loudspeaker in which the diaphragm is suspended by rubber bands or coil springs.