Jack- Sonic Boom Splicer

  He drew his gun, opened the door, took two steps through—and was slammed in the chest by the force of a Sonic Boom plasmid. The sonic shock wave made him stagger back painfully hard against the doorframe. A leering, goggle-eyed splicer in a ragged T-shirt was crouched behind a tumble of crates. “Gotcha big-badge! Or should I say big ass!” He pointed his hand to fire off another Sonic Boom, but Sullivan, sobering fast, slipped back through the door, taking cover to one side
...

She looked down to see a curved fish-gutting knife blade protruding under her breastbone, spurting blood. She toppled forward, dying, and the Sonic Boomer who’d stabbed her from behind leered … and gestured—Wham—Sullivan was flung to skid down the ramp on his back …

  Dazed, he lay there a moment, staring at the ceiling, gasping for air—then he sat up … and looked through the open door, about four paces off at what he thought was the splicer, sneaking around in the shadows.

- Bioshock: Rapture, chapter 17