text: Appendix J
  HEARING
  J-9. Hearing is more acute in the dark for several reasons: mental concentration increases; background
  noises tend to diminish; and, lower temperatures and higher humidity carry sound farther. Practice and
  training help the Soldier overcome fear of night sounds. Training helps him to discriminate (distinguish)
  multiple sounds, faint sounds, and the directions from which sounds originate. Table J-2 shows how far
  away the Soldier can hear particular sounds at night.
  Table J-2. Sounds and distances.
  Source Distance
  Cannon shot 0.0 to 15.0 kilometers
  Single shot from a rifle 2.0 to 3.0 kilometers
  Automatic weapons fire 3.0 to 4.0 kilometers
  Tank movement
  On a dirt road 0.0 to 2.0 kilometers
  On a highway 3.0 to 4.0 kilometers
  Motor vehicle movement
  On a dirt road 0.0 to 500.0 kilometers
  On a highway 0.0 to 1.0 kilometers
  Movement of troops on foot
  On a dirt road 0.0 to 300.0 meters
  On a highway 0.0 to 600.0 meters
  Small-arms weapon loading 0.0 to 500.0 meters
  Metal on metal 0.0 to 300.0 meters
  Conversation between a few men 0.0 to 300.0 meters
  Steps of a single Soldier 0.0 to 40.0 meters
  Axe blow, sound of saw 0.0 to 500.0 meters
  Blows of shovels and pickaxes 0.0 to 1,000.0 meters
  Screams 0.0 to 1,500.0 meters
  Oars on water 0.0 to 2,000.0 meters
  SMELL
  J-10. Smell is the Soldier's least used sense. Typically, he only uses two percent of its potential.
  Different diets produce different human odors. For example, habitual meat eaters smell different from
  habitual vegetarians. Most enemy have different diets from those of US Soldiers. Once US Soldiers learn
  the enemy's characteristic odor, they can easily detect him at night. Practice improves skill and confidence.
  J-11. Facing into the wind at a 45-degree angle makes sensing odors easier. The Soldier relaxes,
  breathes normally, sniffs sharply, thinks about specific odors, and concentrates. Table J-3 shows the
  distances at which the human nose can typically sense particular odors.