The recovered sound was clearest when using objects like the smartphone stand or trash can, and least clear with the venetian blinds—but still audible to make out every word in some cases. Nassi points out that the ability to capture sounds from window coverings is particularly ironic. “This is an object designed to increase privacy in a room,” Nassi says. “However, if you’re close enough to the venetian blinds, they can be exploited as diaphragms, and we can recover sound from them.”

The Ben Gurion researchers named their technique the Little Seal Bug in an homage to a notorious Cold War espionage incident known as the Great Seal Bug: In 1945, the USSR gave a gift of a wooden seal placard displaying the US coat of arms to the embassy in Moscow, which was discovered years later to contain an RFID spy bug that was undetectable to bug sweepers of that time. Nassi suggests that the Little Seal Bug technique could similarly work when a spy sends a seemingly innocuous gift of a metallic trophy or figurine t