Final answer:
Sound travels through the air to an observer in the form of sound waves. These waves are created by a vibrating source and propagate through the air by causing the air molecules to vibrate. When the sound waves reach the observer's ear, they cause the eardrum to vibrate and are then converted into electrical signals that the brain interprets as sound.
Step-by-step explanation:
When sound travels through the air to an observer, it does so in the form of sound waves. These waves are created by a vibrating source, such as a musical instrument or a person's vocal cords. When the source vibrates, it creates a disturbance in the air molecules, causing them to move back and forth in a pattern. This pattern of motion is then carried through the air as sound waves.
As the sound waves travel through the air, they cause the air molecules in their path to vibrate. These vibrations are then passed on to neighboring molecules, creating a chain reaction that allows the sound to propagate through the air.
When the sound waves reach the observer's ear, they cause the eardrum to vibrate. These vibrations are then transmitted to the inner ear, where they are converted into electrical signals that can be interpreted by the brain as sound.