These ceiling mounted speakers from Holosonic Research precisely direct a beam of sound so it can only be heard if you’re standing directly inside the focused area they project.
Their square Audio Spotlight speakers easily mount in place of standard 2′ x 2′ ceiling tiles and project a perfectly focused tunnel of sound towards the people standing beneath them. Step into the beam, and you’ll be able to hear the sound. Step out, and you won’t hear a thing. Designed for applications such as in-store marketing and exhibit design, they’d also be pretty cool mounted in an entryway or hallway.