The glass front of the automated bakery display case began to sing a thin, vibrating note that set Clara Vance’s molars on edge.
It was not a musical tone. It was a rhythmic, sub-audible shudder that crawled up through the soles of her rubber-soled boots and lodged directly in the center of her rib cage. Across the vast three-story interior of Apex Super-Mart, four hundred fluorescent light tubes flickered simultaneously, their magnetic ballasts whining in sympathy with the unseen tremor.
Clara stood on the mezzanine walkway above Aisle 14, her thumb instinctively adjusting the knurled gain dial of the bone-conduction transducer clamped behind her right ear.
The carrier signal was gone.
For ten hours of blackout, her brass transducer had held a clean forty-two-hundred-hertz carrier tone -- the steady electrical heartbeat of the Vance family ledger. Now, that frequency was being crushed beneath a massive acoustic steamroller. The tiny brass diaphragm against her temporal bone was pulsing at eighteen point nine hertz, vibrating with enough mechanical displacement to make her vision blur at the edges.
Eighteen point nine hertz, Clara thought, her fingers tightening around the brass dial until her nails dug into the metal. *The resonant frequency of the human ocular orbit. When you vibrate an eyeball at eighteen point nine cycles per second, the vitreous humor deforms.
