Leo had bought the stairs because his house was too quiet, and his morning routine was too dull. By the second day of installation, the standard oak staircase had been replaced by sleek, black-and-white pressure-sensitive panels.

: Companies like ThePianoStairs.com and Mister Piano offer permanent or temporary interactive installations for public or private spaces.

The first time Leo climbed them, he didn't just go to bed; he performed a clumsy C-major scale. Do-Re-Mi-Fa... he paused on the fifth step, the Sol vibrating through the soles of his slippers. He laughed, a sound he hadn't made in weeks.

One rainy Tuesday, his neighbor, Mrs. Gable, knocked on the door. "I keep hearing Mozart coming from your hallway," she said, peering inside.

True musical stairs are rarely sold as "off-the-shelf" home furniture; they are typically custom-ordered installations or modular kits: