Baltimore Symphony Orchestra musicians feel acoustics have improved for them by an average of 82 percent at Meyerhoff Symphony Hall because of about 22 new stage-wall devices called "diffusors" and "abffusors" that in one form or another are likely to become permanent.
When asked about successes of the 1990-91 season, David Zinman, music director, named the acoustical units the biggest plus of the year. "These are going to mean a great deal to us" in hearing better and playing better, he said. "They give us great confidence."
Peter D'Antonio, the designer who quoted Zinman as saying, "It's a [special] joy coming to work" because of the bookcase-like devices, said the innovation also benefits the audience. He said a sampling of audience opinion was also positive: "The brass is less harsh and the strings are fattened."
D'Antonio, president of RPG Diffusor Systems Inc., of Largo, explained that the orchestra can produce secondary reverberations, or brass and percussion can make too-loud sounds, both unwanted by orchestra players as they play. The audience may well not notice.
Although the Meyerhoff, opened in 1982, is acoustically a fine hall, musicians sometimes couldn't hear themselves or other sections clearly enough because the stage made such lively sounds. This could adversely affect playing, and ultimately, audience enjoyment.
The problem was apparent to engineers for Telarc International when the BSO began recording music with the company in 1987. Enter D'Antonio, a Brooklyn-born scientist, acoustical engineer and ex-bass player and vocalist. Looking closely at reflection patterns, D'Antonio experimented with various baffles and sound diffusors. The musicians were enthusiastic.
Zinman agreed and said keep working. Diffusors were used to cut reverberation, abffusors were put behind the percussion and brass to absorb some volume. They differ mainly in their vertical and horizontal markings.
Developed after 1982 when the hall opened, diffusors "are like a faceted mirror, a diamond, with many surfaces distributing light," said the designer, who has worked on acoustics with 1,000 facilities. "The sound is distributed more evenly.
"The units also have Plexiglas cantilevered tops that direct sounds from outer players like basses and second violins so the inner players, the woodwinds, hear the outer sounds better.
"I think you can hear [the advancement] in the new [BSO] Stravinsky Firebird recording," D'Antonio added. "There is a lot more depth of feeling in the sound . . . the stronger or fatter strings and minimizing the harshness of the brass . . . better rhythm, better timing."
David Bakkegard, BSO principal horn, said whereas players before may have heard "a wash or mush of orchestral sound," afterward, "the sound was much drier and clearer on stage, and we could hear each other much better."
"In a survey," D'Antonio said, "the positive response of the musicians was staggering. George Alexsovich, the general manager, asked them questions such as how well can you hear your own instrument, others nearby, other sections, how easy is it to produce their own tones [the quality of the sound] and hear their intonation better [their pitch]."
The players felt their ensemble hearing -- and playing -- leaped forward. "Their general response was an average improvement of 82 percent," said D'Antonio. "But some reported as much as 130 percent."
The wooden diffusors, about eight feet high, were placed along the three walls in a three-week spring test. The test prompted the orchestra to leave them up, with minor adjustments, while permanent equipment is considered.
The BSO removed the diffusors for the recent Mahler Symphony No. 8 epic because room was needed on the stage. The reflectors and absorbers will return for the six Summerfest concerts July 11-27 and the start of the new season in September.