Hearing is one of the five human senses.

Hearing | Sight | Smell | Taste | Touch

How We Hear

We use our ears to hear sounds.

Sounds travel through the air and our ears as sound waves.

How We Hear

• Sound waves are collected by the outer part of the ear, called the pinna.

• The pinna is the only part of the ear that you can see with your eye.

How We Hear

• After the sound waves are collected by the pinna they are sent through the ear canal before reaching the ear drum.

• When the sound waves hit the ear drum, it vibrates.

How We Hear• The vibrations from the ear

drum make three small bones in the ear vibrate. o The hammero The anvilo The stirrup

• Those three bones together are called the ossicles.

hammer

anvil

stirrup

How We Hear• The vibration of the

ossicles transfer the sound waves to the inner ear.

• The inner ear has two parts, the cochlea and the semicircular canals.

• The semicircular canals. help you determine movement and to stay balanced.

semicircular canals

cochlea

How We Hear• As the sound waves pass

through the cochlea, they cause microscopic hair cells to vibrate.

• These hair cells, called cilia, are linked to the auditory nerve. When the cilia vibrate they send an electric impulse signal to the brain.

• When the signal reaches the brain, we hear!

From David J. Lim. Functional Structure of the Organ of Corti: A Review. Hearing Research, 22 (1986) 117-146

cochlea

auditory nerve

Cilia

How We Hear• As the sound waves pass

through the cochlea, they cause microscopic hair cells to vibrate.

• These hair cells, called cilia, are linked to the auditory nerve. When the cilia vibrate they send an electric impulse signal to our brain.

• When the signal reaches the brain, we hear!

From David J. Lim. Functional Structure of the Organ of Corti: A Review. Hearing Research, 22 (1986) 117-146

cochlea

auditory nerve

Cilia

Now imagine not being able to hear your friends

and parents talk.

That’s Hearing Loss!

• When we are exposed to noises that are too loud, our tiny hair cells in the cochlea vibrate too hard.

• The vibrations cause them to break and bend.

From David J. Lim. Functional Structure of the Organ of Corti: A Review. Hearing Research, 22 (1986) 117-146 Elsevier

NIHL (Noise-Induced Hearing Loss)

Hearing loss as a result of prolonged or sudden exposure to loud noise.

NIHL• Once our microscopic hair

cells bend and break, they will never be straight again.

• There is no surgery to fix the hair cells, once they are damaged they will never work properly again.

• To treat NIHL visit an audiologist.

From David J. Lim. Functional Structure of the Organ of Corti: A Review. Hearing Research, 22 (1986) 117-146 Elsevier

An audiologist is the person you visit to have your ears checked.

• He or she will look inside your ears to make sure everything looks alright

• He or she will do a hearing test to make sure you are hearing everything alright.

If the audiologist finds that you have hearing loss, he or she will work with you to select and fit hearing aids so you can hear again.

Audiologist

• 30 dB Whisper• 60 dB Normal

conversation or a dishwasher

• 70 dB A vacuum Cleaner

• 80 dB Alarm Clock

• 90 dB A hair dryer, or lawn mower

• 100 dB MP3 players at full volume

• 110 dB Concerts and sporting events

• 130 dB Ambulance

Noise levels or loudness are measured in decibels (dB).Any loud noise over 85dB is considered loud enough to cause NIHL.

Levels of Noise chart.

3 Ways to Protect Your Hearing

Walk Away

• If the noise around you is too loud, walk away.

• Moving back 10 or 15 feet from the noise can make the noise going into your ears less loud.

• If you are in a noisy place, make sure you only stay for 30 minutes, if you are not wearing any ear protection.

Turn It Down

• When TVs, car stereos, and MP3 players are turned up too loud, the noise can hurt your ears.

• Turn down the volume to protect your ears.o Keep the volume at 50%.o When listening to anything with ear buds or ear phones, if

someone next to you can hear what you are hearing, the volume is probably too loud.

Wear Ear Protection

• If you know you are going to be in a loud area with noise over 85 dB, wear ear protection. o Earplugso Custom (made to fit your ear) earplugs See an audiologist for these, similar to what musicians and

pilots wear.

If you think you or someone you know might have

a hearing problem, tell your parents to go online to

www.HowsYourHearing.orgto find an audiologist near you.

Questions???