(April 21) Ever been strolling through a Safeway, humming a tune to yourself, only to be interrupted by voices in your head?
And the voices are telling you to buy leeks — even though you never do — because there’s a special on them? And then you succumb to said voices?

No?

Well, you probably haven’t visited a certain Safeway in Fremont, Calif.

The Pleasanton, Calif.-based retailer has been experimenting with commercial applications for a controversial device the military also plans to use for crowd control.

The gadget sends a sort of reverse sound wave that can only be heard by the intended recipient. Without the use of conventional speakers, it is able to send a narrowly focused sonic beam that is inaudible until one walks into its line of projection.

Put your head just inches to either side of the beam, and you won’t hear it. The beam can even be programmed to stop producing sound after a certain distance.

Called HyperSonic Sound, it’s the brainchild of American Technology Corp., San Diego, which also has developed versions for the military that send debilitating, high volume beams that cause severe headaches to unruly protesters or whomever else it is aimed at.

Police used the contraption last year at the free trade conference in Miami, according to The Wall Street Journal, and soldiers in Iraq will be able to use such devices to communicate with people approaching a checkpoint, far before any militants could mount a surprise attack.

At Safeway, the partner introducing the ad messages is Walt Disney Co.’s ABC television network, which is considering an in-store network of plasma screen TVs to target consumers at checkout with ad messages, as well as promote ABC shows, according to The Journal.

Unlike in previous tests, the TVs in the Fremont store use HyperSonic Sound to target those in line only, so cashiers don’t get numbed by hearing loop upon loop of the same messages.

Throughout the store, four larger TVs spin Safeway ads along with other, more subtle messages, including: “Oh, baby carrots. They’re so dang cute.”

Like I said, be careful of voices in your head.