1. Eardrum Sound waves hit a thin skin call the eardrum. The sound waves cause the eardrum to vibrate. Three Tiny Bones As the eardrum vibrates, it causes the three tiny bones to vibrate.

3. Liquid in the Ear When the tiny bones vibrate, they cause the liquid to vibrate. The liquid carries the sound waves to nerve endings. Nerve The nerve endings carry the Messages to the brain.

5. The loudness of sound is measured in decibels. Sounds over 100 decibels (dB for sound) will damage the ears. Airplanes 100-150 dB Jackhammer 100 dB Loud music 90-95 dB Talking 40-60 dB Whispering 20 dB

6. Stethoscope Microphone Bullhorn Hearing Aid