The New Sound

Modern sound engineers have worked marvels of clear acoustics. But have they made too much of a good thing? The question was raised after London's Royal Festival Hall was completed four years ago, and it came up again after the first concerts in the new concrete-domed Kresge Auditorium at the Massachusetts Institute of Technology (TIME, June 29, 1953). "The sensation," wrote Boston Herald Critic Rudolph Elie, after a Boston Symphony concert, "is thrilling to the last degree." But he called the hall "acoustically naked," pointed out that a "creaking shoe, a blow through the exhaust valve of a horn, and a noisily turned page become a major catastrophe."

In the U.S., acoustics-conscious as never before since the advent of hifi, Kresge Auditorium is becoming something of a test case.

Kresge's sound was shaped by Bolt, Beranek & Newman, acoustical engineers, headed by Dr. Richard H. Bolt, M.I.T. professor of acoustics. Into the design went a number of considerations, e.g.:

P: The need for appropriate loudness, i.e., to match the size of the room to the sound source. Kresge (capacity: 1,200) is a multi-purpose hall, seems ideal for small ensembles or chamber groups, but a shade too small for a full orchestra.

P: The need to eliminate background noise. Kresge is not menaced by anything quite so formidable as the subway that runs near Carnegie Hall, but M.I.T.'s city campus presented problems. Kresge is insulated by outer glass walls, curved entrance ways, rubber stripping on doors.

P: The need to distribute sound so that everybody can hear equally well and without delay. Sound weakens as it reaches the rear of a hall, so it must be made denser by reflection from hard flat surfaces. In Kresge, that job is done by hard-surfaced "clouds" hung from the ceiling.

These are problems that every architect of a music auditorium has had to consider and solve, often by trial and error (many older halls have adequate acoustics because of such accidents of general design as coffered ceilings, panels, statuary, friezes, all of which helped to diffuse sound). But the chief factor that gives modern halls their characteristic clarity and brilliance is close control of reverberation, i.e., the prolongation of sound.

Soft Symphonies. Beethoven and composers who followed him were accustomed to halls in which the reverberation period was comfortably long, i.e., if they clapped their palms, it would take perhaps two seconds for the sound to die to inaudibility. Result: when an orchestra played, it sounded mellow, sometimes foggy. Composers wrote symphonies to be performed under those conditions, and musicians played their instruments no better than necessary to pass muster under the mellow fog. Until the electronic age, except for musicians playing outdoors, everybody was accustomed to the old sound. When Toscanini first walked into NBC's studio 8-H, he clapped his hands, heard the echo die within a second and passed his judgment: "Too sec" i.e., dry. He was referring to the shorter reverberation time, achieved by acoustical engineers who could prove that it made music sound clearer. At Kresge, the reverberation time is 1 1/2 seconds, actually a compromise, but unusually sec to conventional ears.

Hard Mechanics. The movement toward acoustic sharpness and clarity was strengthened by FM radio and hi-fi phonograph reproduction. People who have learned their music via hi-fi complain, when they hear live symphony orchestras for the first time, that the music is too soft and not brilliant enough. Veteran musicians, on the other hand, complain that hi-fi sound is mechanical and unreal. Sound Engineer Bolt, aware that taste in sound changes, believes that many people today do not want merely faithful reproduction but actually a new sound.

He has not made up his mind about Kresge Auditorium. On concert nights, Bolt and his associates may be seen busily picking up unpremeditated opinion from critics and public about the hall's acoustics. Orchestra men generally like it, because they can hear each other as the sound bounces off the "clouds" (in most halls, a violinist hears little beyond the string section, a trumpeter hardly anything except the brasses). So far, the novelty of being able to hear so clearly has convinced audiences, too, that Kresge is an acoustic marvel. But if, as seems likely, it becomes the acoustic model for other halls, the music of the future is sure to have a radically different sound.

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