Brain and the Auditory System: An Introduction to Neuroscience
|Program||Brown Science Prep|
|Developed by||Kaylyn Shibata|
|Developer Type||Brown students|
Overview / Purpose / Essential Questions
Sound is one of the most important elements in our lives, something that adds
to the meanings of our lives. Think for a moment: what would it be like to live
in a world with no sound? (ask the class)
Try to imagine such a world: there would be no sound or noise in that world.
We would never know about a danger approaching from behind. There would be no music (No Lady Gaga!!) We would be unable to communicate with our loved ones, or pass on information to others without great difficulty.
Now imagine you were asked to build a machine that could process and decode sound waves. Even if you were given all the proper materials and equipment, rest assured it would be quite impossible to do. It is one thing to capture sound, but another to translate it into a mental thought that even links with emotions. That is why the auditory system is such a marvel to scientists. Our ears, are a system superior to even modern day sound capturing devices, and still baffle scientists today.
Psychoacoustics: The study of the structure of the ear and the way sound is received, transmitted, and understood by the brain.
Anatomy and physiology of the auditory system
Outer ear: cartilage forms the outsides of the ear to help funnel noise. (Possibly show examples of different types of ear structure, such as in rabbits, vs. hippos). Sound waves enter an auditory canal, which leads to the eardrum, which marks the beginning of the middle ear
Middle ear: once sound hits the tympanic membrane, or ear drum, This wave information travels across the air-filled middle ear cavity via a series of delicate bones: the malleus (hammer), incus (anvil) and stapes (stirrup). These ossicles act as a lever and a teletype, converting the lower-pressure eardrum sound vibrations into higher-pressure sound vibrations at another, smaller membrane called the oval (or elliptical) window.
Inner ear: Cochlea (spiraled shaped) is filled with a fluid which moves from sound vibrations. The movement of this fluid, sets in motion “hair cells” which converts this motion to electrical signals. This is where the exterior sound is turned into a an electrical impulse!
Hair Cells: Listen to your ipod too loud and you’ll kill them all! Hair cells are responsible for relaying the sound waves into chemical signals that can travel to your central auditory system in your brain. They encode the sound and transmits the information to neurons.
Central Auditory system.
In the cochlear nucleus, the first brain relay station for sound, signals encoding sounds are not just passed on, but rather are "dissected" and sorted first. This means that different features of a sound, such as frequency, intensity, or onset and offset (beginning and ending of a sound) are carried to higher brain centers separately. That way your brain is not overloaded with auditory information! Acts as a filter!
Why do we need two ears?
How does timing, and the intensity of a sound in the two ears tell the brain where the source is? (do an experiment with blindfolds and various sound identification)
The brain uses the differences in the timing and intensity received between the two ears to locate the position, which explains why it is hard to identify a noise directly behind you.
Cocktail party effect
The cocktail party effect describes the ability to focus one's listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations. The effect enables most people to talk in a noisy place.
Shows how your brain can sort through information and process only what is relevant.
Therefore patients with APD will either take in too much information or not enough.
Hearing in animals:
Hearing is not a very common ability as the other senses (touch and taste) and is mainly restricted to vertebrates and insects, with mammals and birds being superiors.
- Humans: 20- 20,000 Hz
- Whales: 20 - 100,000 Hz
- Bats: 1500 - 100,000 Hz
- Frogs: 600 - 3000 Hz
- Fish: 20 - 3000 Hz
- Crickets: 500 - 5000 Hz
Frequency, intensity, and decibel levels
Intensity level of sound is measured in decibels. As Frequency increases, the intensity increases (A dependent relationship!). ** Add an little extra physics lesson here** with possible experiment.
Importance of hearing- Alzheimer and music… the cure for memory loss?
Have students participate in the current on going debate about whether or not music can be a stimulus for memory. Is there an time in your life when you have had a memory triggered by a sound? Have students recall experiences and the thought processes that they went through. Then, tie in personal experiences, with the actual path neurons take. This will solidify the pathways.
Wrap up / Conclusion
Protect your ears! people should consult a doctor when an ear infection occurs or when symptoms such as pain in the ear, constant ringing, dizziness, discharge, or bleeding occur. Another critical behavior for preventing hearing loss is to avoid exposing ears to loud noises, either by avoiding noisy situations or by using earplugs or ear covers. High noise levels damage or kill hair cells.
Supporting Web Information
|Audience(s)||High school students
|Grade Level(s)||High School
|Created||08/26/2011 06:47 PM|
|Updated||12/20/2018 10:58 AM|