You are not in a car ad. You are in a city, maybe Chicago … yes, the “city of big shoulders,” as Carl Sandburg called it. You look. You walk. You’re on the train. You sit reading an art book by a clanging radiator, looking out an apartment window. You spot a pretty girl and a handsome guy walking down the street, disappearing around the corner. Suddenly, you’re in a restaurant eating eggs and ketchup, maybe blueberry waffles. Then, a dark corner bar sneaking a gin and tonic. Now you’re in a recording studio messing with knobs. Red lights blink on consoles and electric guitars lean silently on slender metal stands. Wherever you go there is music: textures, mixes, sonic fizz, blips, bleeps, thundering beats, pitter-patter grooves, horns honking, string section swirls, distorted power chords, ticklish little melodies, mumbled words. This is the world of the Chicago bands Tortoise and The Sea and Cake.

With their fourth and fifth full-length albums respectively, these two groups continue to refine their sounds. For Tortoise, refinement means further developing its brawny yet brainy instrumental groove music. The band pumps life-fluid into the PVC pipes and computer cables that connect electro-funk, dub, dance, fusion, reggae and prog-rock. With songs like the oddly metered “Benway,” the heavy-beating “Eden,” the vibraphone-ringing “Blackjack,” and the techno-tinged “Monica,” Tortoise creates a cerebral, artsy sound. It’s jam-band bliss minus the patchouli: more geeked-out, collegiate, hipsterish, digitized, decked out in black-framed glasses and Campers rather than satchels and sandals.

If Tortoise muscles its way through the city of big shoulders with a Phish tie-dye beneath its black turtleneck sweater, the Sea and Cake makes music that glances off the skyscrapers high above. Indeed, the band’s new songs virtually dissolve into the ether. The tunes are full of pretty melodies, with Sam Prekop’s impressionistic lyrics more mumbled streams-of-consciousness than fleshed-out story lines, and luscious arrangements that shower an invisible dew of fluttering guitars and gentle, bossa nova rhythms across glass and steel, neon and shiny billboards. Songs such as “All the Photos,” “Two Dolphins,” and “Midtown” seem to sibilate like champagne. As in the best pop music, Oui bubbles effervescently. But unlike your typical pop, a crisp, dry sophistication keeps it from turning stale.