I. Musical instruments
 A. Woodwinds
  1.
 B. Brass
 C. Strings

 D. Percussion
  1. Drums
   a. Bass

II. Nature
 A. Wind
 B. Running water
 C. Surf/tides
 D. Storms
  1. Rain
  2. Lightning
  3. Thunder
  4. Tornado/hurricane wind

 E. Earthquake
 F. Treefalls
 G. Calving glaciers
 H. Landslide
 I. Fire
  1. Crackling (small)
  2. Roaring (big, forest fire)
III. Animals
 A. Horses
  1. Neighs
  2. Clopping hooves
 B. Cats
  1. Meows
  2. Hissing
  3. Purring
  4. Yowling
  5. Raaaaaaaaeeeerrrrrrrrrrrr!

IV. Cars & bikes
 A. Engines
  1. Revving
  2. Idling
 B. Tires squealing
 C. Crashes 
 D. Horns
V. Aircraft
 A. Light planes
 B. Helicopters
 C. Jets

VI. Weapons
 A. Guns
  1. Automatic
  2. Single shot
 B. Cannons
 C. Explosions
  1. Incendiary
  2. Concussive
VII. Cooking
 A. Sizzles
  1. Deep fryer
  2. Pan
 B. Running faucet
 C. Boiling
 D. Microwave
 E. Popcorn popping
 F. Chopping
 G. Teapot whistle

IX. People
 A. Babies
  1. Crying
  2. googoo gaga
  3. Laughing
 B. Body functions
  1. Sneezes
  2. Coughs
  3. Yawns
  4. Farts
 C. Screams
 D. Singing
 E. Footsteps

X. Household
 A. Doors
  1. Sqeaking
  2. Slamming
  3. Doorbells
 B. Floorboards squeaking
 C. Phonerings
 D.