The acoustical canopy hanging over the stage of San Francisco’s Davies Symphony hall is made of 59 6-foot squares of Plexiglas. They replaced 19 “giant contact lenses” (oval reflecting dishes) ten years ago and are still noteworthy enough to warrant an Chronicle article (albeit during a slow news week). The computer-controlled panels are often fined-tuned for each piece, like the mixing board for an amplified rock band, creating the correct blend and reflection for the various orchestra instruments. Here’s a 1992 Chronicle review of the acoustically flashy opening performance at the newly renovated Davies Hall.