Hearing and the Ear

What is Sound?

​4.4 Hearing

What is Sound?

Sound is vibrations that travel through air or a medium and can be heard when they reach a person's or animal's ear.

​Medium - air, liquid or solid.

Sound needs a medium.

​What medium do you think sound travels fastest in?

What are the children doing?

What Causes Sound?

Sound is made because of vibrations.

What are Vibrations?

Vibrations are back-and-forth motions....WAVES.

Waves

We may think of the word "wave" as something you do with your hand, or what we see in water. What does is mean in physics?

Waves

In physics, a wave travels through matter transferring energy from one place to another.

Multiple Choice

What kind of waves vibrate our eardrums so we can hear?

• Microwaves

• Water Waves

• Light Waves

• Sound Waves

• Radio Waves

Multiple Select

What two things are needed to create sound.

• light

• vibration

• ears

• a medium

Pitch

What is pitch?

High Pitch

High pitch refers to a high sound. Smaller instruments make a higher pitch.

Low Pitch

The larger an instrument, the lower the sound.

Multiple Choice

Which instrument do you think will have a higher pitch?

Multiple Choice

Which instrument has a lower pitch?

What is frequency?

Frequency, sometimes referred to as pitch, is the number of times per second that a sound pressure wave repeats itself.

Frequency and High Pitch

The more times a wave passes in a given period of time, the higher the frequency.

Frequency - Low Pitch

The fewer number of waves that pass in a given period of time, the lower the pitch.

Multiple Choice

Look at the picture. Which sound wave represents a low pitch and low frequency?

• Sound A

• Sound B

Volume

Volume tells us how quiet or loud a sound is.

Amplitude

Amplitude is also referred to the wave height. The taller the wave, the louder the sound.

Multiple Choice

Which wave has a greater amplitude?

• Solid Line

• Dotted Line

Multiple Choice

Which wave has the quietest volume?

• 1

• 2

• 3

The ear can be divided into 3 parts:

• The Outer Ear

• The Middle Ear

• The inner Ear

The ear has 2 jobs:

• 1 to help you hear

• 2 to help you keep your balance

Outer Ear

• Made of cartilage and soft tissue called the Pinna

• the pinna collects the sound vibrations around us and sends then into the ear canal.

• The Pinna helps us decide the direction and source of sound.

Middle

• Ear Canal: funnels the sound to the ear drum.

• Ear Drum: collects the vibrations from the air and passes it to the middle ear.

• the ear canal is where you also find ear wax

Middle Ear

• The middle ear contains three tiny bones, called the Ossicles.

  hammer/anvil/stirrup

• They are the smallest bones in the human body, they transfer vibrations from the eardrum to the cochlea.

• Eustachian Tube goes from your ear to your throat. It helps remove fluid and balance pressure on your ear drum.

Inner Ear

• Cochlea is filled with fluid and hair cells. When vibrations enter, the hair picks them up, vibrate and create and electric signal.

• The cochlea changes the vibrations into electrical signals that the brain can use. If damanged can cause hearing loss

• The auditory nerve sends signals to the brain

• The semicircular canals - filled with fluid and help us keep our balance.

• ​The auditory nerve takes nerve signals from the cochlea to the brain.

• The brain interprets the signals as sound.

• interpret - to make sense of.

Multiple Choice

What is the job of the cochela?

• Take in sound from outisde and turn it into vibrartions

• to keep your balance

• Change vibrations into electrical signals the brain can use.

Multiple Choice

Do we have hair in our ears?

• Yes

• No

Multiple Choice

How many bones are in our ears?

• One

• Two

• Three

Multiple Choice

What is the job of the ear drum?

• Ear Drum collects the vibrations from the air and send to the middle ear.

• Ear Drum creates electonic sound waves.

• Ear Drum makes sound

Earwax moistens your ear canal and helps keep you from getting infections.

​Different animals can hear different sounds.

Bats use sound and their hearing to catch insects.

Elephants use very low frequency sound to comunicate through forests over long distances.

Dolphins use sound to find fish and even stun them. Dolphins can hear the most frequencies.

​Bats hunt insects at night. They see with sound.

We call using sound to see, sonar.

​An Elephants ear is big and can hear very low frequencies.