You know something special is happening when Josh Groban shows up in jeans. The vocalist was one character amongst many to interpret the songs of Paul Simon -- and also to sing with the folk great --

You know something special is happening when Josh Groban shows up in jeans.

The vocalist was one character amongst many to interpret the songs of Paul Simon -- and also to sing with the folk great -- on April 24 at the Brooklyn Academy of Music. It was the second night of the "American Tunes" segment of the month-long residency, a night to celebrate more than four decades of Simon's quintessential American song craft.

With younger, up-and-coming artists like Grizzly Bear co-mingling with staples from an older generation like the Roches, there was bound to be some mixed reactions or, at the very least, some surprises. The latter trio, for instance, was first put on the map when they appeared on Simon's 1973 set "There Goes That Rhymin' Simon" and made some pretty significant folk records in the '70s and '80s. But their take on "Cecelia," despite one particularly batty Roche sister's odd dance groove, was too tame for fun and too lethargic to kick the set off right.

Olu Dara also failed to connect with much of the crowd, as he went off on a practically indiscernible monologue during "Slip Slidin' Away," though his able backing band set a fiery groove to "Still Crazy After All These Years."

On the other hand, artists like Amos Lee came out to scant applause but exited to standing ovations. First delivering "Peace Like a River" with soul and delicacy, Lee loosened up the Simon canon even more with "Nobody" and "Homeward Bound"; he even eked a shimmy or two out of his body, which could have boiled into a sweet twist and shout if it weren't for the guitar strapped to his back.

Brooklyn's excellent Grizzly Bear also made some thoughtful contributions to "Graceland," the epitome of the American traveling song. With layered harmonies and an impressive pedal board of nasty reverb and delay, the young quartet also put a spooky spin on "Mother and Child Reunion."

Groban's soaring vocals were impressively scaled back for "America," a song with lyrics that demand such sweetness. Sweeter still was Groban as Art Garfunkel on "Bridge Over Troubled Water," Simon trading verses with him and letting Groban take the lead on the epic finale to the song.

Gillian Welch and the ever-breathtaking David Rawlings were an instant attraction, bringing their floor-stomping and finger-picking styling to "Gone at Last" and getting the audience clapping in time. The participation angle continued through "Duncan," with onlookers in a near tizzy by the end of the pensive classic "Sound of Silence." Welch shakily harmonized on the latter, but ultimately delivered an incredibly warming performance.

Simon himself isn't the firebrand he used to be as a vocalist, though he made a great performance out of "Me and Julio Down By the Schoolyard." He played a few more of his newer songs, including "How Can You Live in the Northeast," an irritating track in its self-conscious profundity.

Aside from a general mellowness that served as the running theme, the night with Paul Simon was an engaging and nostalgic one. One does not go to see Paul Simon to be introduced to what's hip or what's new, but because it's a terrifying and wonderful reminder of how many classic songs the man has written -- songs about the history of the country as much as his own personal one.