1. Hearing Sound – Travels through the air in waves – Caused by changes in air pressure that result from vibration of air molecules – Anything that makes a sound causes vibrations Pitch – How high or low the sound is – The pitch of a sound depends on its frequency – Frequency – the number of cycles per second (length of the waves) – Men’s vs. Women’s voices Loudness – Determined by the height (amplitude) of sound waves – Measured in decibels

2. Pitch

6. Loudness

10. The Ear Shaped to capture sound waves, to vibrate with them, & to transmit sound to the brain Outer ear – captures sound Eardrum – transmits sounds to three small bones in the middle ear – Stirrup – Hammer – Anvil Inner Ear – Cochlea – Bony tube that contains fluids as well as neurons that move in response to vibrations in the fluids – The movement generates neural impulses that are transmitted to the brain via the auditory nerve

11. The Ear

12. Deafness About 2 million Americans are deaf – May be inherited or caused by disease, injury, or old age Conductive Deafness – Occurs because of damage to the middle ear, which amplifies sound – Unable to hear sounds that are loud enough – Use hearing aids to improve amplification of sounds Sensorineural Deafness – Unable to perceive sounds that are certain frequencies – Caused by damage to the inner ear – Often neurons (hair cells) in the cochlea are destroyed – Damage to the auditory nerve – Hearing aids DO NOT help

13. Deafness