Severance Hall - Acoustics

Acoustics

Some acoustic problems were soon observed in Severance Hall shortly after its opening. These were attributed in part to the use of velvet curtains for the boxes, thick carpeting throughout much of the hall, and the fact that the stage, designed for theatrical productions, had a large, sound-absorbing fly space above it. In addition, the removable stage shells created for the orchestra to play within were constructed of non-sound-reflective materials, which also allowed sound from the hall's original organ to be heard from its position above the stage's fly space. The 6,025-pipe Ernest M. Skinner organ was a massive instrument for its day, but its positioning outside the auditorium itself was something of an experiment and limited choices for addressing the auditorium's dry acoustics.

In 1958, at the instigation of Music Director George Szell, a complete acoustical redesign of the hall was undertaken. To make the auditorium more resonant, the original proscenium and blue velvet drapes were removed and the placement of carpet was reduced to a minimum. On the stage a permanent acoustical shell was built (affectionately known as 'The Szell Shell'). The new shell consisted of thick wooden walls surrounding the orchestra in a series of convex curves. The heavy wood walls were further filled with sand to heights of up to nine feet to make them less absorbent and more reflective of sound. The result was a new, vibrant-sounding space which complemented the refined, brilliant sound of the orchestra under Szell's direction.

Visually, however, the severe new Modernist stage clashed with the elegant Art Deco design of the auditorium. In addition, the organ's pipe chambers were effectively sealed off from the auditorium by the new shell. This made the organ all but non-functional, its sound being transferred into the auditorium via microphones and speakers.