During its 30 years as an ensemble, the Emerson String Quartet has emulated its namesake--Ralph Waldo--by boldly establishing a distinct style. The musicians alternate first and second violin positions, play standing (with the cellist on a small podium), and deliver ensemble perfection that's truly athletic. This program sandwiches Terra Memoria, by Finnish composer Kaija Saariaho--her second quartet, dedicated "for those departed" and premiered by the Emerson at Carnegie Hall on June 17--between two late Beethoven quartets. The concert opens with his Quartet no. 16 in F, op. 135, which gets one of the best performances in the Emerson's recording of the cycle: their propulsive, unsentimental style suits Beethoven's delinquent rhythms, yet they still manage a profoundly searching slow movement. The concert ends with Quartet no. 13 in B-flat, op. 130, played with its original last movement, the imposing Grosse Fuge. The Emerson's recording of this movement (published, and often performed, separately) gives coherence to Beethoven's craggy writing but misses some of its savagery. a 8 PM, Martin Theatre, Ravinia Festival, Green Bay & Lake Cook Rds., Highland Park, 847-266-5100, $10-$50.