Login

Mechanics of Hearing & How the Brain Processes Sound

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Taste, Touch & Smell: Proprioception & the Somatosensory System

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
 Replay
Your next lesson will play in 10 seconds
  • 0:27 Sound
  • 0:43 Soundwaves
  • 2:45 Parts of the Ear
  • 4:01 Frequencey Theory
  • 4:30 Place Theory
Add to Add to Add to

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Login or Sign up

Timeline
Autoplay
Autoplay
Create an account to start this course today
Try it free for 5 days!
Create An Account

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Ellie Green

Ellie holds a B.A. with Honors in English from Stanford University. She is pursuing a Ph.D. in English Literature at Princeton University.

How do our ears transform sound into signals that our brains can process? In this lesson, you'll cover properties of sound waves and how they interact with key parts of the ear.

Introduction

Did you know where the smallest bones in your body are? They're not in your fingers and toes; they're actually in your ear, and they make up a part of the complicated mechanism that allows our ears to turn vibrations in the air into the sounds that we hear.

Sound Waves

Sound is made up of molecules vibrating in patterns called waves. When I bang on a drum, the drum's vibrating surface disturbs the air in patterns that, once they reach my ear, can be interpreted as a sound. Unlike light, which can travel in a vacuum through space, sound waves need material to travel--they need some sort of matter to disturb.

Frequency

Sound waves that are shorter hit our ears in more rapid succession; they are said to have a higher frequency. Frequency is related to the idea of pitch in music, or the relative highness or lowness of a given sound. When an opera singer hits a high C, she is producing sound waves that are very short and with a high frequency. When a tuba plays a low C, its sound waves are much longer and with a lower frequency.

Loudness

Loudness is related to another feature of the sound wave, called amplitude. Amplitude is basically the size, or height, of the sound wave. The bigger the wave, the louder the sound. You may have heard the term decibel ; that's a scale, rather like degrees for temperature, for saying how loud something is. Unlike degrees, however, the decibel scale is logarithmic. This means that if one sound is 10 decibels louder than another, it's actually ten times as loud. A 60 decibel conversation is ten times as loud as 50 decibel rainfall; a 110 decibel rock concert is ten times as loud as a 100 decibel snowmobile. A 90 decibel lawnmower is 100 times louder than a 70 decibel vacuum cleaner--ten times ten. The scale starts at the threshold of human hearing, so zero decibels represents the point at which a sound becomes so quiet that humans can't detect it. Prolonged exposure to noises above 85 decibels can cause hearing loss, either by physically damaging the ear or by damaging the nerves that transmit signals to the brain.

Interpreting Where Sound Is Coming From

You know how when you hear a noise, you can usually tell where it's coming from? This is because we have two ears, spaced apart on either sides of our heads. This means that if a sound is coming from the left, it reaches the left ear sooner than it reaches the right. While the difference in time might be really small, your brain automatically interprets this to help you determine where the sound is coming from.

Parts of the ear involved in hearing
Ear Parts

Processing Sound

Now that we've learned about sound, let's take a look at how the ear processes sound and turns it into signals that can be interpreted by the brain. Sound first enters the ear and reverberates around the pinna, or folds of cartilage in the outermost part of the ear. Then it travels down the auditory canal, which amplifies the sound until it hits the eardrum. The eardrum rests up against the ossicles, which are those tiny bones we were talking about at the very beginning. There are three of them, and they help transform the sound from vibrations in the air to vibrations in the fluid inside the nearby cochlea. The cochlea looks kind of like a twisty seashell; it's filled with fluid and with small hair cells that support bundles of cilia, small fibers that can sense vibrations in the fluid. These hair cells send nerve impulses to nearby neurons. These signals then travel down the auditory nerve and into the brain. There are a lot of parts of the ear to remember, so I like to use a kind of mean acronym to remember them: if you don't know how hearing works, Please Exit Our Cool Crowd. Pinna, eardrum, ossicles, cochlea, cilia. This is the order in which soundwaves enter the ear and are processed; Please Exit Our Cool Crowd.

To unlock this lesson you must be a Study.com Member.
Create your account

Register for a free trial

Are you a student or a teacher?
I am a teacher

Unlock Your Education

See for yourself why 30 million people use Study.com

Become a Study.com member and start learning now.
Become a Member  Back

Earning College Credit

Did you know… We have over 95 college courses that prepare you to earn credit by exam that is accepted by over 2,000 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it free for 5 days!
Create An Account
Support