A GIANT VOICE

Radio Record, Volume I, Issue 3, 5 August 1927, Unnumbered Page

A GIANT VOICE

a vv ‘A WONDERFUL NEW HORN Motorists along an open road near Pittsburg, Pa., U.S.A.,. recently were amazed by the thunderous music of a brass band playing a march, although ati empty hillside lay between them ‘and the nearest building, three-quarters | ofa mile away. Despite the absence ‘of aty visible source of music, they subsequently heard, sweeping fc ath with full volume and » the swelling chords of the pipe organ, the crashing crescendoes of a great male chorus, piping piccoloes, booming bass drunis, and velvety-voiced violas. The occasion was a public demonstration, attended by newspaper men, music critics, and electrical cngineers, of the latest form of loud-speaking device for which a patent has just been granted to Clinton R. Hanna and Dr Joseph Slepian, the inventers, both members of the Westinghouse Electric Company’s research staff.

New Acoustic Device. This development, which establishes another milestone in the progress of acoustic science, is built fundamentally around a type of reproducing and radivating device called the exponential horn. ... The underlying principle of the new .process is proper coupling between the da@vhragm and the surrounding atmos--phere, which is the essential feature "of improved mechanical phonographs and horn-type 1eproducers. The new _arrangement has gone a step further than any preceding development, in making possible the reproduction, at full volume, of the deep bass of the organ and drum. ‘The anditors at this particular demonstration were highly impressed with the merit of the. exponential horn, and of the reproducing element used in conjunction with it. The reproducing element is of radically new type, especially adapted for this horn. Fall Volume of Al} Pitches.

It was. explained by the inventors. that although :t is relatively easy to erfect a reproducer capable of covering the full range of pitches at small intensities, it is, however, a much more difficult problem to provide load capacity adequate for the assurance of full volume at all pitches. And it is significant that the lower pitches, which constitute the backbone of many musical compositions, are the most difficult t. reproduce at great intensities. | One of the records used to test the loud-speaker was the "Lost Cherd," «s sing in the Sesquincentennial Auditorium by 2500 voices, comprising the associated glee clubs of America. The bass of this gigantic chorus stood ont with impressive intensity. Nor were shades ef pitch or nuance of voice ebsent in the chords that swept across hill an¢ | dale adjacent to the pole. ‘he fact that the low-frequency notcs were not obtained at the sacrifice of the highfrequency notes was obyious in the closing strains of the ‘Lost Chord." The embellishments which this chorus arrangement gives to the first tenors were heard with utmost clarity riding serenely on snbstantial nndercurrents of first and second bass and second tenor. The ensemble of pipe organ and voices in the Oaklev Portugal arrangement of ‘‘Adeste Fideles,’? by the same chorus, was another number that adequately tested the reproducing capacity of the new lond-speaker. A conversation addressed to the auditors was clearly understood, even at the great distance intervening, this being a most difficult test surmounted by the device Great Sound Effect.

The device produces the sound effect of a horn fourteen feet long, but actually is only forty-eight inches in each direction. Its name, the exponential horn, is based on the mathematical formulae used in calculating its peculiar internal curves. It is due to this that sound of all pitches, low as well as high, receive accurate rendition and correct volume. Although the apparatus used _in this demonstration radiates from Yen to twenty times more volume than the ordinary loudspeaker, there is no distortion in the reproduced sound; this feature being one of outstanding importance to acoustic engineers. It is curious to note that despite the tremendous volume of sound, which can be sent rolling among the hills a mile away, the amount of electrical energy represented by ail this sound is only about 24 watts, or less than that of a flashlight lamp. ‘The apparatus was not especially designed for lightness, yet there is no art of it which cannot be carried by with the exception of the great wooden horn, and even that can be replaced by a lighter one at some sacrifice of volume in the lower pitches, It was explained by the inventors that it is relatively easy to perfect a reproducer capable of covering the full tange of pitches at small intensities. However, far more difficult is the problem of providing load _ capacity adequate for the assurance of full volume at all pitches. Namby-pamby bass, the sort often reproduced, that conveys the sound of a feverish moan, was conspicuous by its absence at the demonstration.

For Public Entertainment. The adaptability of a loudspeaker of this type to various community enterprises of music or entertainment may readily be umderstood. As applied to a concert in a public park, where band . concerts and other municipal programmes are staged, the horn would eliminate any necessity for crowding, or feverish jockeying for parking places near the stand, Jndged by the demonstration recently, the, concert ‘ auditor, shonid he decide to park nearly a mile away, would enjoy the concert as well as those near the stand, Other major applications of the device will be in Jarge auditoriums and in connection with talking movies,