by Mark B. Anstendig
©1996 The Anstendig Institute
The San Francisco Opera House has one of the most uneven acoustics in the world and fixing it would cost only a fraction of the multi-millions of dollars presently being spent on the building's renovation and seismic retrofit. Bathrooms, dining areas, seats, carpets, and other areas that have nothing to do with the building's purpose are all being renovated. Yet not a penny is being spent on the very reason for the building's existence: the sound.
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The most expensive seats, the box seats along the sides of the house, have the worst sound. On the right side, the listener hears mainly first-order overtones of instruments on the opposite, left side of the pit or stage. The sound is almost devoid of the fundamental tones that the musicians are actually playing. When the violins are playing, which is most of the time, their overtones drown out almost everything else. The boxes on the left similarly hear mostly first-order overtones from instruments on the right. The fundamentals are drowned out. Tympani overtones and overtones from the lower instruments overwhelm everything else. The imbalance is so strong, and the result so confusing to the ear that the music is disfigured. The listener does not hear, as he should, what the musicians themselves are playing and hearing.
The right and left sides of the first ten or so rows of the orchestra sections suffer from the same anomalies, with the sound slowly improving farther back in the hall. The center of those rows has a better, though not excellent sound. The sound improves towards the center of the orchestra sections, and the back sections under the balconies have good sound. In the standing room area, at the back of the hall, the volume level is much lower, but the sound quality is excellent.
Seats in the various levels in the back of the hall above the orchestra level have better sound, improving further back. The standing room areas at the very back of these levels have the best, most homogeneous sound of all.
The reason for these acoustic anomalies is the large sections of bare, strongly reflecting walls on either side of the hall directly in front of the stage, between the proscenium and the first boxes. These walls continue back, with only the boxes to break them up. The acoustic anomalies occur because higher and lower frequencies radiate differently. Higher frequencies radiate more in straight lines in the direction they are aimed, while lower frequencies radiate less direction specifically, and more in all directions. Reflecting walls increase the higher frequencies more than lower frequencies, because of differences in the way those frequencies radiate: the more directly radiating, higher frequencies that would not have reached the listener are reflected back into the hall more strongly than the more diffusely radiating lower frequencies. Since harmonics are higher frequencies than fundamentals, these walls are the reason for the emphasis of overtones.
The solution for the uneven acoustic would be to increase the sound-absorbency of the main reflecting walls, and possibly the ceiling. Because of the uncomplicated layout of the hall and easy access to reflecting areas, a good acoustician could easily make the hall one of the acoustically best in the world.
During the renovation The Anstendig Institute called the Opera House to inquire about corrections to the acoustic. The administrative officer disagreed that the acoustic was bad, saying that it was a matter of opinion. The poor acoustic of large sections of the Opera House auditorium is a scientifically measurable reality, not opinion. However, after a century of bad, distorted sound reproduction1 and sound reinforcement2 as its main source of music, the public has lost its ability to distinguish between distorted and correct, undistorted sound quality.
Society urgently needs sources of undistorted, natural sound as a frame of reference to determine and adjust the correct sound quality of its various electronic sound sources. The San Francisco Opera House, as a non-profit, publicly supported organization, has an obligation to become such a reference point, especially when millions of dollars are being spent on renovations. Yet it appears doomed to remain an acoustic anomaly and neither the public nor its administration nor its funders seem to realize it.
1 See our papers on sound-reproduction.
2 Sound reinforcement is the name for all amplified live sound.
The Anstendig Institute is a non-profit research and educational institute that studies the vibrational influences in our environment, particularly those of sights and sound, and how they affect sensory perception. Its papers on sound reproduction, problems of focusing in photography, psychology of hearing and seeing, and erratic vibrational influences that affect our lives are widely distributed throughout the world. All are available free of charge.