5. Sensory Thresholds A candle flame can be seen from a distance of 30 miles on a clear night. Can hear the ticking of a wristwatch in a quiet room at 20 feet. Can feel a bee's wing fall on your cheek from 1 centemeter. Can taste 1 teaspoon of sugar in 2 gallons of water. Can smell a drop of perfume diffused throughout a 3-room apartment.