Biopsychology Exam 3 - Ch. 7.1

Front 1

Define: "sound waves"

Back 1

Sound waves are periodic compression of air, water, or other media

Front 2

What does the "amplitude" of a sound wave refer to?

Back 2

The amplitude refers to the amplitude of the function representing the sound wave aka the intensity of the sound wave; i.e. how much the air is being compressed

Front 3

What is "loudness" and how does it relate to amplitude?

Back 3

Loudness is a sensation related to amplitude, but not identical to it. Sometimes, a sound can be perceived as louder than other sound of identical physical amplitude, e.g. rapid speech versus slow music (rapid speech sounds louder)

Front 4

What does the "frequency" of a sound wave refer to?

Back 4

The frequency of a sound wave is the number of compressions per second, measured in Hertz (Hz, cycles per second).

Front 5

What is "pitch" and how does it relate to frequency?

Back 5

Pitch is a sensation related to frequency; sound waves with high frequencies are perceived as high pitch noises, and low frequency sound waves are perceived to be low pitch noises.

Front 6

What is the range of frequencies that the human ears can hear?

Back 6

Adult humans can hear sounds ranging from about 15 Hz to around 20,000 Hz. Children can hear slightly higher frequencies, because as we age and are exposed to loud noises, our ability to hear those higher frequencies decreases.

Front 7

Describe the structures of the outer-ear.

Back 7

-pinna
-external auditory canal

Hint 7

The "pinna" is the thing sticking out of the side of your head made of cartilage; sound waves are reflected and altered by the specific shape of your individual pinna, and helps your brain locate where sounds are coming from.

The "external auditory canal" is where you stick your Q-tip in; sound waves travel through this canal after being bounced around the pinna.

Front 8

Describe the structures of the middle-ear.

Back 8

-tympanic membrane/eardrum
-hammer
-anvil
-stirrup

Hint 8

The "tympanic membrane" or "eardrum" is located between the external auditory canal and the rest of the middle- and inner-ear; the tympanic membrane vibrates to the exact frequency as the sound waves that strike it.

The "hammer", "anvil", and "stirrup" are three tiny bones which, in that order, connect the tympanic membrane to the oval window; because the stirrup is much smaller than the tympanic membrane, the sound waves' amplitudes are increased as they are carried through these three tiny bones on their way to the inner-ear.

Front 9

Describe the structures of the inner-ear.

Back 9

-oval window
-cochlea
*scala vestibuli, scala media, and scala tympani
*hair cells
*basilar membrane
-auditory nerve

Hint 9

The "oval window" is the membrane behind the stirrup and the cochlea of the inner-ear.

The "cochlea" is a snail-shaped structure which has three fluid-filled tunnels in it and contains the auditory receptors. The sound waves were amplified by the structures of the middle-ear because now those waves must set in motion the fluid in the cochlea, which requires more intensity than vibrating the tympanic membrane, which is surrounded by air.

The three fluid-filled tunnels are called the "scala vestibuli", the "scala media", and the "scala tympani" and all run along the length of the curled-up cochlea.

The auditory receptors, called hair cells, are located along the "basilar membrane", a membrane within the scala media of the cochlea.

"Hair cells" are displaced by the vibrations of the fluid in the cochlea.

Hair cells, in turn, excite the cells in the "auditory nerve", which carries the information back to the auditory cortex for coding.

Front 10

What is "place theory"? Explain the theory and it's problems.

Back 10

The "place theory" is one attempt to explain how information from sound waves is coded such that we can distinguish between differences in frequency and pitch.

Hint 10

The theory postulates that the basilar membrane containing the hair cells is set up like a piano, where each area of hair cells responds to a certain frequency. One end of the membrane's hair cells responds to the lowest frequency sounds, and the other end responds to the highest frequency sounds, with the full range of possible frequencies arranged along it.

The problem with this theory is that the cochlea is curled up so that different areas of hair cells that are not next to each other on the length of the basilar membrane are very close together and could interfere with each other.

Front 11

What is "frequency theory"? Explain the theory and its problems.

Back 11

The "frequency theory" is another attempt to explain how information from sound waves is coded such that we can distinguish between differences in frequency and pitch.

Hint 11

The theory postulates that the basilar membrane vibrates in synchrony with a sound, so that the action potentials of the auditory nerve axons are fired at the same frequency as the sounds you are hearing. So, a sound at 50 Hz would cause 50 action potentials per second.

The problem with this theory is that the refractory period of a neuron prevents it from firing any faster than 1000 times per second, which would translate to 1,000 Hz, which is far below the 20,000 Hz cap of our adult human range of hearing.

Front 12

What is the current theory explaining how information from sound waves is coded such that we can distinguish between different frequency sounds?

Back 12

A combination of the "place theory" and the "frequency theory".

Hint 12

This theory postulates that for very low-frequency sounds (up to about 100 Hz), the basilar membrane vibrates in synchrony with the sounds waves, in accordance with the frequency theory, and one action potential is sent out per wave. So, at low frequencies, the number of firing cells identifies loudness and the frequency of impulses identifies the pitch.

When frequencies get higher than 100 Hz but are less than 4000 Hz (which is the range of where most human hearing takes place), neurons work together by firing at different points every few cycles (instead of every cycle) thereby sending a "volley" of signals which fires are the frequency of the sound wave. So, instead of one individual neuron firing once every cycle, several neurons work together to create the same effect.

When hearing the highest frequency sounds (over 4000 Hz), the hair cells seem to fire at certain points of the membrane and not others, as described in the place theory.

At higher frequencies,

Front 13

What is the technical term for what is often called "tone deafness"?

Back 13

It's called "amusia".

Hint 13

It is an impairment in the detection of frequency changes, and it occurs in 4% of people.

Front 14

How does the information coded by the inner ear get passed along to the part of the brain where it is processed?

Back 14

Axons carrying information from the cochlea cross over in the midbrain and signals travel to the "primary auditory cortex" or "area A1" the superior temporal cortex.

Though both areas A1 on each side of the brain receive info from both ears, MOST of the input comes from the opposite-side ear.

Front 15

What similarities are there between the organization of the auditory cortex and the organization of the the visual cortex?

Back 15

Like in the visual cortex, there are distinct pathways to interpret the WHAT and the WHERE of sounds. There are separate parts of the primary auditory cortex which interpret where a noise is coming from/whether it is moving
and
what the noise sounds like/what we guess is making the sound.

Front 16

Auditory Imagery: explain

Back 16

Just like the visual cortex (which is active during visual imagery), the auditory cortex is active when a person imagines/remembers sounds, even if they aren't actually hearing them at the time.

Front 17

What does the term "tonotopic map" refer to?

Back 17

Individual cells in the primary auditory cortex have preferred tones, arranged along a gradient from one end of the area A1 to the other, responding to low and high frequencies on opposite ends, much like the somatosensory cortex is set up.

A cell will respond best to it's preferred frequency sound accompanied by its harmonics.

Front 18

What is the difference between the "primary auditory cortex" and "secondary auditory cortex"?

Back 18

The "primary auditory cortex" has the tonotopic map thing going on, and receives information about the frequency/pitch of the incoming sound.

The "secondary auditory cortex" is surrounding the primary auditory cortex, and works much slower. It responds more to changes in sound, and interprets the meaning of incoming sounds (e.g. animal cries, music, machinery noise, etc)

Front 19

What are the two types of hearing loss and how do they differ?

Back 19

-Conductive deafness/middle-ear deafness
-Nerve deafness/inner-ear deafness

Hint 19

"Conductive/Middle-Ear Deafness" happens when diseases, infections, or tumors prevent the middle ear from transmitting sound waves properly. It is sometimes temporary and can be corrected by surgery or hearing aids amplifying the stimulus.

"Nerve/Inner-Ear Deafness" happens as a result of damage to the cochlea, the hair cells, or the auditory nerve. It can occur in any degree and may only affect one part of the cochlea, resulting in the person being deaf to specific frequencies only. Nerve deafness can be inherited or it can develop from prenatal problems or early childhood disorders.
Hearing aids cannot compensate for extensive nerve damage, but sometimes help people who lost some receptors in part of the cochlea, but can still hear.

Front 20

What is "tinnitus" and what is it caused by?

Back 20

It is a constant or frequent ringing in the ears, and is often a result of nerve deafness.
In some cases, it is caused by a phenomenon much like phantom limb in the somatosensory cortex.

Front 21

What are the three main ways we use our two ears to detect the location of an incoming sound? In which situations do we use each one?

Back 21

1) The difference in loudness of a sound in each ear,
2) The differences in phase of the sound wave as it hits each ear, and
3) The difference in time of arrival of the sound to each ear.

Hint 21

1) High frequency sounds create a "sound shadow" behind our heads, resulting in the sound being slightly louder in one ear than the other.
So, we use loudness to localize high frequency sounds.
2) Low frequency sounds transmit better through solid objects (such as our heads) and so there is less difference in loudness in each ear, but the phase will be much different because of the long wavelengths of low frequency sounds.
So, we use phase differences to localize low frequency sounds.
3) If the sound is sudden enough, we use the time of arrival to locate any frequency sounds.

Front 22

What is the "somatosensory system"?

Back 22

the sensation of the body and its movements, including:
-discriminative touch
-deep pressure
-cold
-warmth
-pain
-itch
-tickle
-position and movement of joints

Front 23

What is the "Pacinian corpuscle"?

Back 23

It is one type of somatosensory receptor located in the skin, which detects sudden displacements or high-frequency vibrations on the skin. It has an onion-like outer structure that provides mechanical support to the neuron, which insulates the neuron against most touch stimuli that is gradual or has constant pressure.

Front 24

What is a "dermatome"?

Back 24

A "dermatome" refers to the skin on a limited area of the body, and each dermatome connects to a specific spinal nerve. However, the lines between dermatomes are indistinct, and they overlap each other quite a bit.

Front 25

What affect does pain have on the prefrontal cortex?

Back 25

The prefrontal cortex, which is important for attention typically responds only briefly to any new stimulus, but with pain, it continues to respond as long as the pain lasts.

Front 26

What is "capsaicin"?

Back 26

It is a chemical found in hot peppers, and it stimulates the pain and heat receptors in your body.

Front 27

Which neurotransmitters are release in the spinal cord by pain axons?

Back 27

Mild pain releases "glutamate", but
stronger pain releases glutamate as well as "Substance P".