Sound is propagated in sound waves, which are (in simple terms) waves of variation in air pressure caused by physical phenomena such as vibrating vocal cords, the vibrations of the reed as air flows through a flute, aircraft 
(Sound; is propagated; L:in sound waves) (sound waves; are; in simple terms) waves of variation in air pressure caused by physical phenomena such as vibrating vocal cords, the vibrations of the reed as air flows through a flute, aircraft) (air pressure; caused; by physical phenomena such as vibrating vocal cords) (air; flows; through a flute, aircraft)
Sound sound waves air pressure air
is propagated are caused flows
L:in sound waves
in simple terms) waves of variation in air pressure caused by physical phenomena such as vibrating vocal cords, the vibrations of the reed as air flows through a flute, aircraft
by physical phenomena such as vibrating vocal cords
through a flute, aircraft