Echo Rooms

Radio Record, Volume I, Issue 49, 22 June 1928, Page 3

Echo Rooms

~ APPLAUSE PRODUCED TO ORDER HOW A SOUND IS MULTIPLIED rE the films made at Hollywood can | show action that never takes place, the B.B.C. can broadcast sounds that are never made. Both can create illusions, The illusions of broadcasting are produced by echoes. In a valley in Sinai, . as in valleys in Switzerland, a single shot fired from a rifle sounds like a Lewis machine-gun in action as the report echoes from side to side of the rocky chasm. A bugle call sounds like. a Boy Scout band, , A Simple Process. HE B.B.C. in the same way can find or create enough echoes of the sound made by a few people clapping their hands to produce the illusion that Madame Clara Butt is being encored | at a benefit performance. The tattoo ou one kettledrum can be multiplied | till it sounds like the massed drums of the Guards when the Dead March is played. , It is as simple as clever. A pair of wires leads from the sound-receiving microphone to a loud-speaker in an empty room, the walls of which are. made of materials that readily echo. any sound made within their compass. The room begins to reverberate with multiplied sounds, the original ones and the echoes. These are in their turn communicated to another microphone placed in the room. Varying the Original Sound. TPE multiplied and magnified sounds this microphone now receives are carried away in their turn to a second echo room, where in the same way they are further multiplied and magnified. This magnification can be extended almost without limit, depending on the number of echo rooms. Now that the method is under control, all sorts of variations of the original sound can be produced to create effects such as could never be heard in any other way. It used to be said that a photograph could never lie, till the photographers showed that it could tell all sorts of stories. The same is becoming true of broadeasting, which will some day make us hear sounds neyer before heard on land or sea.