Hearing

Audition• Begins with sound

entering ear• Sound: physical energy

caused by vibrating objects.

• Vibrations produce movement of air molecules (sound waves)

• Moving one’s head aids in detecting sound source

Audition

Characteristics of Sound

1. Loudness2. Pitch3. Complexity

Characteristics of Sound• Loudness: dimension of hearing related to the intensity

of a wave’s pressure• Corresponds with amplitude, or maximum height, of a

sound wave• The more energy contained in the sound wave, the

higher it is• Measured in decibels

Noise & Toys

http://www.npr.org/templates/story/story.php?storyId=5044711

Characteristics of Sound

• Pitch: Frequency of the sound wave• Frequency: how rapidly the air vibrates– Number of times per second the wave cycles from peak

to peaks– The greater the number of cycles, the higher the pitch

• Measured in hertz

Pitch

Wavelength

Highest Frequency? Loudest? Highest Amplitude? Highest Pitch?

A. B.

C.

Characteristics of Sound

• Complexity: Distance of the range of frequencies– Wavelengths

• Usually what we hear is a combination of several subwaves with different frequencies

• This is what distinguishes one sound from another– Same note played on a

flute will sound different when played on a clarinet

Virtual Keyboard!

http://www.bgfl.org/bgfl/custom/resources_ftp/client_ftp/ks2/music/piano/

Anatomy of the Ear

• Pinna: external visible flap of skin and cartilage

Anatomy of the Ear

• Auditory Canal: part of outer ear along with pinna

• Leads to eardrum

Anatomy of the Ear

• Eardrum: separates outer ear from middle ear

• Vibrates with reception of sound

Ear Wax

• Produced by glands in outer ear to protect inner ear from infection

• Sticky substance prevents dust, dirt, and bags from getting in

Be Careful!

• Q-Tips can be dangerous!

• Can push wax further into eardrum

• Can even perforate, or break, your eardrum

YOLO.

What Do Doctors Suggest?

• “Just leave it alone,” says Dr. Andrew Chang, an ear, nose, and throat specialist.

• Wax slowly moves up and out of the ears on its own, dries up, and flakes off or washes away when you shampoo your hair.

My name’s Dr. Chang,

and I’m unabashedly disgusting.

Anatomy of the Ear

• Ossicles: three bones in middle ear– Hammer– Anvil– Stirrup

• Smallest bones in the body

• Transmit sound vibrations to the cochlea

Eardrum

Auditory Canal

Ossicle Bones

Anatomy of the Ear

• Cochlea: part of inner ear

• Contains fluid & receptors

Inside the Cochlea• Contains 25,000 tiny

hair cells known as cilia

• Transmits sound frequencies into electrical impulses

How Do I Remember All of These?

• Please• Exit• Our• Cool• Crowd

• Pinna• Eardrum• Ossicle Bones• Cochlea• Cilia

How Does Sound Move Through the Ear?

http://www.oticon.com/eprise/main/Oticon/com/SEC_AboutHearing/LearnAboutHearing/Products/SEC_OtiKids/Kids/AboutHearing/CNT10_HowDoesTheEarWork%20

Types of Deafness

Conduction Deafness• Caused by the failure of the

three tiny bones inside the middle ear to pass along sound waves to the inner ear or the failure of the eardrum to vibrate in response to sound waves

• Possible cause is a build-up of fluid

• Hearing aids • Normal hearing may return.

Sensory-Neural Deafness• Damage to the inner

ear. Most often caused by loss of hair cells that will not regenerate.

• Damage to the auditory nerve.

• Cochlear implants can help patients with this form of deafness.

Stimulation Deafness

• Exposure to very loud sounds

• Prolonged exposure to 85 dB can cause stimulation loss.

• Ringing sound can mean hair cells have been damaged