Artec, headed by famed acoustician Russell Johnson, is among the leading sound designers in the world. The company's projects have included Morton H. Meyerson Symphony Center in Dallas, the Esplanade performing arts center in Singapore, and the New Jersey Performing Arts Center in Newark.

The orchestra left the Academy of Music for Verizon Hall in large part because of the Academy's acoustic deficiencies (paradoxically, those deficiencies are sometimes credited with encouraging the development of the lush "Philadelphia sound"). When Verizon Hall opened in December 2001, however, reports on the hall's acoustics were mixed. At the time, Artec and the orchestra said that it was not fair to judge the hall, since work was not entirely complete. But after a series of adjustments, the company now says that a more thorough overhaul is needed.

Specifically, Artec suggests that more than 100 wood-and-fiberboard doors leading into an acoustical chamber that surrounds the auditorium be replaced with concrete. Such a "monolithic and massive design," which would make the design more similar to Artec's other halls, would help increase the "sound energy" that reaches the audience.

The company also makes a series of secondary recommendations, including replacing a series of panels around the hall with harder, more sound-reflective materials.

It is not clear which of the recommended actions, if any, the orchestra or the Kimmel Center will take. In interviews with the Inquirer, Kimmel Center president Janice Price and orchestra president Joeseph Kluger praised the hall's acoustics, and said that the report was part of the long-term process of tinkering with a new hall.