structure-borne audio

Turning an ordinary surface into a loudspeaker. A small transducer is bonded to a rigid panel — a window, a wall, a table top, a car windscreen — and vibrates it so that the panel itself radiates sound. There is no cone and no visible speaker. The sound appears to come from the surface, or from the room itself.

This is a mature commercial technology rather than a hypothesis, and it is inexpensive.

Documented real-world example: Feonic’s “Whispering Window” mounts to glass with a peel-and-stick adhesive pad, installs in seconds, works on any pane 6 mm or thicker, and is marketed to retailers precisely so that audio reaches passers-by outside the glass. A Dayton Audio DAEX25 exciter pair retails at $32.99 with adhesive pads included. Continental ships the same principle in vehicles under the name Ac2ated Sound, driving the windscreen and trim panels instead of fitting conventional speakers.

Two properties matter for anyone weighing a claim. Every documented method requires physical contact with the surface; there is no evidenced way to drive a window from a distance. And the sound produced is real sound in air — a second person in the room hears it, and an ordinary microphone records it.

Related terms: parametric array, piezoelectricity, Voice-to-skull, microwave auditory effect

Sources: Body sound converter — Monacor; Whispering Window — Feonic; DAEX25 Sound Exciter Pair — Dayton Audio; Ac2ated Sound — Continental