Listeners have never shied from making acoustical judgments about the centerpiece of the $265 million Kimmel, citing a somewhat pallid orchestral sound and lack of impact. Musicians on stage said they had difficulty hearing one another.
In truth, Verizon Hall is a vast improvement over the Academy of Music, if one's abiding criterion is pure sound, as opposed to old-world ambiance or the alluring ghost memories of having heard Stokowski and Rachmaninoff amid the gilded splendor.
Verizon is still sleek, its mission acoustical efficiency. Which makes this summer's reconstruction of some critical bones in the 2,500-seat hall all the more tantalizing. The first visual clues are anything but subtle.
Two large boxy appendages, in brown tones much darker than the rest of the honey-toned interior, have appeared on either side of the stage. Weighing 7,152 pounds each and sealed with heavy sound-bouncing doors, the "reflector towers" effectively shrink a portion of the stage by about 24 feet. Despite their bulk, the towers are movable, gliding on tracks.
A stealthier change is the reconstruction of an acoustical wall behind the wooden latticework ringing the stage. The new masonry wall is bulkier than the old, and it has been reshaped from its former smooth quarter-moon curve to something more jagged and complex to bounce sound back out on stage and into the hall.
The two bits of remediation and a few others over the summer carried a combined $1.3 million price tag, and are aimed solely at improving sound - for the players on stage as well as the audience.
Based on hearing one Philadelphia Orchestra concert this season, Dawn R. Schuette, the Chicago acoustician from Threshold Acoustics leading the project, said an improvement was apparent. One major goal was to boost the orchestra's presence, and in that first concert, "the overall power of the orchestra was wonderful."
Any difference comes in part from an additional change made in summer 2010, when the ceiling between the organ and organ chamber was reinforced. It might not seem like a major aspect of Verizon's acoustical grand scheme. But the area is large - 800 square feet - and the very thin ceiling was allowing orchestral sound to escape into a kind of aural limbo, heard by no one.
So thin were the materials over the organ that "organists would avoid the lowest four notes on the organ because they would hear the ceiling moving," Schuette said.
The solution demanded a major new piece of engineering. The old ceiling was kept, but it was backed with several layers of laminated wood and a honeycomb material. The heavier structure weighs much more, so a web of steel trusses was fabricated and installed to hold it all in place.
Very little orchestral sound now leaks out into the chamber above the organ, Schuette said, making the remote space relatively quiet - except, of course, when the organ is being played. The modification cost $600,000, a sum picked up by Frederick R. Haas, the philanthropist and organ enthusiast who has been the major patron of the Fred J. Cooper Memorial Organ.
Over the summer, sound was further preserved in smaller ways by sealing Verizon's interior and exterior doors on the orchestra level. Gears were replaced, which should eliminate the clanking of closing doors during concerts that can disrupt listeners' concentration. (Doors on the other levels will be refurbished in a future summer.)
The woodwork was completed according to a design of Voith & Mactavish Architects by the hall's original craftsman at Architectural Woodwork Industries (both are local firms).
"We were all trying to think about how to make the onstage entrance of the conductor a more elegant experience," architect Daniela Voith said.
With all these physical changes, what kind of acoustical experience will reach the ears?
This will be a listening year. No hall can be judged on a single night. Acousticians and others will spend the season listening to the changing repertoire, from different seats in the house, with audiences large and not so large, before any decisions are made about further work.
Variables such as the size of the ensemble on stage and the number of bodies in the audience can make a big difference in the sound.
It's easy to forget that Verizon is not just an orchestra hall. Pop music concerts, single-instrument recitals, and other events are held there - often electronically enhanced - and on these occasions, temporary adjustments are made, such as pulling open acoustical curtains or raising or lowering the acoustical canopy over the stage.
"I think what we want to do is test [the hall]," Kimmel president Anne Ewers said. "I would be ecstatic if this achieves our goals," she said of the hardware changes made to the hall since opening night.
In the meantime, Verizon Hall is, year in and year out, perhaps spawning ghost memories of its own. Rachmaninoff won't be visiting, but, with both Lang Lang and Yuja Wang performing this season, any paucity of impact sensed in the hall won't stem from a lack of sonic charisma at the source.
Contact music critic Peter Dobrin at 215-854-5611 or firstname.lastname@example.org. Read his blog at http://www.philly.com/artswatch.