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By the end of this section, you will be able to:
  • Describe the basic anatomy and function of the auditory system
  • Explain how we encode and perceive pitch
  • Discuss how we localize sound

Our auditory system converts pressure waves into meaningful sounds. This translates into our ability to hear the sounds of nature, to appreciate the beauty of music, and to communicate with one another through spoken language. This section will provide an overview of the basic anatomy and function of the auditory system. It will include a discussion of how the sensory stimulus is translated into neural impulses, where in the brain that information is processed, how we perceive pitch, and how we know where sound is coming from.

Anatomy of the auditory system

The ear can be separated into multiple sections. The outer ear includes the pinna    , which is the visible part of the ear that protrudes from our heads, the auditory canal, and the tympanic membrane    , or eardrum. The middle ear contains three tiny bones known as the ossicles , which are named the malleus    (or hammer), incus    (or anvil), and the stapes    (or stirrup). The inner ear contains the semi-circular canals, which are involved in balance and movement (the vestibular sense), and the cochlea. The cochlea    is a fluid-filled, snail-shaped structure that contains the sensory receptor cells (hair cells) of the auditory system ( [link] ).

An illustration shows sound waves entering the “auditory canal” and traveling to the inner ear. The locations of the “pinna,” “tympanic membrane (eardrum)” are labeled, as well as parts of the inner ear: the “ossicles” and its subparts, the “malleus,” “incus,” and “stapes.” A callout leads to a close-up illustration of the inner ear that shows the locations of the “semicircular canals,” “urticle,” “oval window,” “saccule,” “cochlea,” and the “basilar membrane and hair cells.”
The ear is divided into outer (pinna and tympanic membrane), middle (the three ossicles: malleus, incus, and stapes), and inner (cochlea and basilar membrane) divisions.

Sound waves travel along the auditory canal and strike the tympanic membrane, causing it to vibrate. This vibration results in movement of the three ossicles. As the ossicles move, the stapes presses into a thin membrane of the cochlea known as the oval window. As the stapes presses into the oval window, the fluid inside the cochlea begins to move, which in turn stimulates hair cells , which are auditory receptor cells of the inner ear embedded in the basilar membrane. The basilar membrane    is a thin strip of tissue within the cochlea.

The activation of hair cells is a mechanical process: the stimulation of the hair cell ultimately leads to activation of the cell. As hair cells become activated, they generate neural impulses that travel along the auditory nerve to the brain. Auditory information is shuttled to the inferior colliculus, the medial geniculate nucleus of the thalamus, and finally to the auditory cortex in the temporal lobe of the brain for processing. Like the visual system, there is also evidence suggesting that information about auditory recognition and localization is processed in parallel streams (Rauschecker&Tian, 2000; Renier et al., 2009).

Pitch perception

Different frequencies of sound waves are associated with differences in our perception of the pitch of those sounds. Low-frequency sounds are lower pitched, and high-frequency sounds are higher pitched. How does the auditory system differentiate among various pitches?

Several theories have been proposed to account for pitch perception. We’ll discuss two of them here: temporal theory and place theory. The temporal theory of pitch perception asserts that frequency is coded by the activity level of a sensory neuron. This would mean that a given hair cell would fire action potentials related to the frequency of the sound wave. While this is a very intuitive explanation, we detect such a broad range of frequencies (20–20,000 Hz) that the frequency of action potentials fired by hair cells cannot account for the entire range. Because of properties related to sodium channels on the neuronal membrane that are involved in action potentials, there is a point at which a cell cannot fire any faster (Shamma, 2001).

Questions & Answers

I want to be a nurse. What is my area of concentration
Sommy Reply
pharmacology and brain structures in psychology
Deepak
learn to love
Cruel
learn to love?.
Deepak
what is subject
Walter Reply
the madness will go away..
Miasco Reply
Hi
Sonic
Hello
MTH
So what is Psychology? Generally
Sonic
its a philysio thereapy
Yan
oh physio therapy
Sonic
right
Sonic
ha ha just kidding
Yan
the scientific study of the human mind and its functions, especially those affecting behaviour 
Yan
Hi everyone. My question is.. How can manage anger? Any therapy name which use in home to manage anger? If someone needs anger management which tips are helpful?
Madeeha Reply
i think that you can manage your anger buy avoiding things which can cause you to be angry just surround yourself with people who doesn't make you angry
Fiona
One of methods in releasing anger in a not-so chaotic way is to simply find a quite place, scream and cry.
Norina
I think allowing yourself to be angry is helpful
jojesstay
^ in my opinion, while being good, avoids the problem. Either confront anger, or/and overcome it. Think about why you feel angry and should you even be angry to even begin with. Its ok to be angry. Everyone is different and react to different situations with dif. emotions, but dont let anger win u.
Tomi
take anger as your best friend ,make it a source of motivation whenever you become angry don't take it as something others do as they take anger as a different entity rather than accepting it as a mere emotion(though the strongest of them all) , so accept anger as an emotional state and accept it...
Priyank
...when it comes just take a deep breath and say to yourself it's nothing or no one else but me and I can control it and after doing it for a time you'll be able to channel it or redirect it in a way which will help you in a lot of different ways that you can't even think or imagine of......
Priyank
just remember anger is not your enemy but just an emotion it's not different from you, it's you and it's your bestest and strongest friend of them all.
Priyank
when you angry just count 100 to 0
Prashanth
Hi, everyone anyone tells.What is the scope of psycholog?
Madeeha Reply
The subject-matter of our science is, then, the Soul or Mind. The psychologist investigates those phenomena which we call sensations, perceptions, thoughts, volitions, and emotions; he analyzes them, classifies them, and seeks to reduce them to the smallest number of fundamental activities.
Vibhu
hey madeeha this is your answer
Vibhu
its my point of view
Vibhu
What matters is how their mind perceives their spirituality. And every mind will perceive this differently. Remove your own spirituality from the equation when studying psychology in order to view the spirituality of others (or lack thereof) as objectively as possible.
Brent
yeah exactly r8
Vibhu
Okay, thanks
Madeeha
Why is Bipolar and Meth use so prevalent amongst bipolar individuals?
Brett Reply
honestly, they are probably diagnosed as bipolar because of the meth. once gotten off meth for any length of time. the symptoms of bipolar usually leave. but few are honest with dr. n tell they use meth
Barbara
Conversely, it's because they self medicate during depressive episodes and become addicted. Manic highs can also lead to feelings of invincibleness and reckless behavior that impair judgment. People in manic states just want to have the most fun possible and find it hard to say no to drugs, or even
Brent
Seek the drugs out. Once they are out of the manic state, they associate the meth with that state, and when depressed will continue to use meth to attain it.
Brent
when used, meth will cause the dopamine levels (I call it your happy part) in your brain to rise to the max. so for the first few intakes of the drug the user will have a major confidence boost and will feel on top of the world. the more the intake, the more higher dosage of the drug has to be used
Shia
therefore, the addiction starts because of the need to feel. my intake on the whole thing is that people that have a mood disorder such as bipolar, or pretty much any body suffering from a mental illness, are more drawn to the drug in order to not feel so numb. but the consequences for using the
Shia
drug on top of, for instance like you said, being bi polar, only causes more of a chemical imbalance in your brain.
Shia
what is a pneumatic depressant
Bill Reply
what is the symptoms of DID.
positive Reply
what is symptoms of DID(Multiple personality Disorder)
positive
4. As indicated in this section, Caucasian women from industrialized, Western cultures tend to be at the highest risk for eating disorders like anorexia and bulimia nervosa. Why might this be?
Shamy Reply
Is anyone know the exact cause of mental illnesses like Add, Adhd, Ocd, bipolar etc
Kartikey Reply
mental desorders are caused by many factors
riadh
a chemical imbalance with bipolar which if i remember correctly has somthing to do with OCD as well.....?
jessie
its also has to do with parts of the brain that recieve neurons and some that dont.
Natasha
Natasha...u from which country?
Philip
uSA
Natasha
no i need more explanation
Aminu
ADD, ADHD, bi polar, and OCD. the first 3 are mostly chemical imbalance to the brain. bi polar is a chemical imbalance that has to do with the emotional and creative parts of the brain. its cause from not getting the right amount of something or not enough of something. which is why amphetamines
Natasha
will either make them act more normal and or helps them concentrate. also can make the unleveled level out. desoxyn is methamphentimine hydrochloride its for obese add and adhd
Natasha
may I add that some studies have shown that children who have A.D.H.D were more than likely brought up in single parent family's and Im not a 100% sure of the stat's but believe that some studies have shown as many as 80% of children with A.D.H.D were brought up in a single parent inviroment.
Gavin
And I also remember A.D.H.D in the early days and ideas were put fourth of the cause and one that stood out was spending excessive amounts of time playing computer games as that was still quite anew phenomena at the time.
Gavin
not that anyone mentions that one any more lol.
Gavin
I don't believe there is such a thing as chemical imbalance. More research is needed and it's too easy and simple just to blame certain illnesses on a chemical imbalance. What is chemical imbalance? Maybe we should start there.
David
chemical imbalance is when you either lack a brain chemical such as seritonin, dopamine ex.
Natasha
gavin true to that. our enviroment is a big factor in our chemicals. when were happy because of something our bodies produce more dopamine
Natasha
for example. single parent families are stressful which studies have shown cause more damage then we think or relize including brain chemistry
Natasha
lol duh read a book every now an den u won't bee sow retar'ed. geez some people I swair jus aint gots no cents. ya knaw what eye sayin... lol
Brett
ask reinfield from dracula he suffers from psychotic ideation...lol
Rodney
it has to do with the lack of dopamine in your brain and how your brain has developed. everyone's development is different and the way it is developed is a major factor
Shia
what are the psychological effects of being a patient
Gloria Reply
why is the Synapse so important to biopsychologists
Susan Reply
I dnt know
Sam
because its very important
Deepak
Because that's where the exchange of information takes place which causes reactions in us and so biopsychologists need to study the info transmitted in order to study the reaction to explain a mental process/behaviour
Tina
synapse occurs as part of the brain activity. This is where everything seems to happen. Just imagine this synapse is like firing information, your feelings, and stuff
Ysa
so can i assume that if there is action potential in the pre synaptic cell but the neurotransmitter does not diffuse into the post synaptic cell that this would lead to some sort of mental dysfunction?
Susan
Or the opposite, too much neurotransmitter
George
how long does it takes to stabilize your sleeping hours?
Gabby Reply
15 minutes.
Philip
90 mnit +
Khadim
usually 24 hrs for me
Goof
30mins to 1hr
Joshua
😉
Sarfaraj
30 minutes
Bill
why do we get depression
meghna Reply
how to be a neuropsychologist?
mukhtar Reply
wo Kya hota h?
Gayatri
I speak English sorry... If you can translate: I suggest studying anatomy if you are still in high school. You will need a master degree. So about ten years of college.
Jen
Pay close attention to psychology as well. Biology is a must.
Jen
hmm
Gayatri

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Source:  OpenStax, Psychology. OpenStax CNX. Feb 03, 2015 Download for free at https://legacy.cnx.org/content/col11629/1.5
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