Stinking sulfur. Sweet peppermint. Sweat. These are the smells of Myron Krueger's laboratory, where virtual reality is taking on a new aroma. Krueger has built an olfactory display system-the nasal equivalent of the head-mounted displays used for visual effects. The portable device dispenses scents from bottles of liquid odorants; tubing carries the vapors to the nose.

Smell's evocative qualities could make virtual reality more convincing, and might help in simulations where odors are an important cue-such as training paramedics or doctors. Krueger's company, Artificial Reality (Vernon, Conn.), is working with a grant from the Defense Advanced Research Projects Agency, which hopes to add "telesmell" to battlefield telemedicine. Krueger, an early pioneer of virtual reality, says the main bottleneck lies in synthesizing smells. While the perfume industry has mastered the ability to produce floral and fruit fragrances, less is known about how to concoct many less pleasant odors.