Exam 2 Flashcards

1
Q

Sound

A

an energy wave of molecules (or pressure wave) that creates a vibration
-vibrations sets particles in the surrounding medium (typical air) in vibrational motion, thus transporting energy through the medium
-cycles per second

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2
Q

Frequency vs intensity and their units

A

Frequency is the rate of pressure fluctuations in the sound wave
-measured in Hertz (Hz)
-how often
vs.
Intensity is the magnitude of the pressure change in a sound wave (amplitude)
-measured in decibels (dB)
-how strong

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3
Q

Pure tone vs. Complex sounds

A

Pure tones are a single waveform for which variation as a function of time is a sine function (Sine wave)
vs.
Complex sounds are a combination of pure tones; different frequencies combined at different intensities

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4
Q

What is Fourier analysis?

A

a method to divide a complex sound into its pure tone components

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5
Q

Basic Structures of the auditory system listed in order

A

Outer Ear
-Pinna
-Ear canal

Tympanic membrane

Middle Ear
-Ossicles

Oval Window

Inner Ear
-Cochlea
-Organ of Corti

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6
Q

Basic Structures of the auditory System and their functions: Pinna

A

=the outer part of the ear that sticks out; the curly structure on the side of the head that we typically call an ear
-The ridges in the ear help detect and localize sounds

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7
Q

Basic Structures of the auditory System and their functions: Ear Canal

A

=the canal that conducts sound vibrations from the pinna to the tympanic membrane
-enhances sound frequencies
-conducts sound vibrations from the pinna to the tympanic membrane and prevents damage to the tympanic membrane

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8
Q

Basic Structures of the auditory System and their functions: Tympanic Membrane

A

= a thin sheet of skin that moves in and out in response to the pressure changes of sound waves
-eardrum; the border between the outer and middle ears

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9
Q

Basic Structures of the auditory System and their functions: Ossicles

A

= 3 tiny bones in the middle of the ear (MIS)
-amplify sound waves and transmit the vibrations from the tympanic membrane to the oval window

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10
Q

Basic Structures of the auditory System and their functions: Oval Window

A

the border between the middle and inner ear
-its movement causes movement of fluid within the cochlea (inner ear)

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11
Q

Basic Structures of the auditory System and their functions: Cochlea

A

=the change in pressure causes the vestibular canal to bulge in a location related to the frequency of the sound
-Interacts with the middle ear to relieve pressure
-These bulges in the vestibular canal cause the middle canal to move up and down shearing the Organ of Corti

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12
Q

Function of the inner hair cells

A

-focus on loudness and pitch
-Each stereocilia is connected to its neighbor by tip link (=a tiny filament)
-So they bend together when deflected by the shearing force
-When a stereocilium ( inner hair cell) deflects, the tip link pulls on the taller stereocilia in a way that opens an ion pore allowing potassium (K+) to flow into the cell => rapid depolarization
-The harder you pull, the more potassium is going to come in
-This depolarization leads to a rapid influx of calcium ions and initiates the release of neurotransmitters- stimulating the dendrites of the auditory nerve

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13
Q

Function of the outer hair cells

A

-Function: makes parts of the tectorial membrane stiffer through an electromotile response; works to make inner cells more sensitive and sharply tuned
-The sharpness of afferent nerve fibers connected to inner hair cells is dependent upon the outer hair cell
-Electromotor response, actually change shape/grow when stimulated
Need more force to stay sturdy
-Adds structures while inner hair cells move

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14
Q

How does the cochlea encode intensity?

A

-If the amplitude of the sound wave is increased, the tympanic membrane and oval window move farther in & out with each pressure fluctuation
=>making the bulge in the vestibular canal bigger, causing the cochlear partition to move farther up & down, causing the tectorial membrane to shear across the organ of Corti more forcefully, which causes the hair cells to pivot farther back & forth, which causes more neurotransmitters to be released, which causes auditory nerve fibers to initiate action potentials more quickly

-The location of the cochlea is frequency and how much it bends is intensity

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15
Q

How does the cochlea encode frequency?

A

-Cochlear place code= different portions of the cochlea are tuned to different frequencies
-different spots that move up and down more
-closer to oval window is high pitch/frequency, closer to the other window is low pitch/frequency

-The location of the cochlea is frequency and how much it bends is intensity

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16
Q

How the nerve fibers are organized to carry frequency information

A
17
Q

What does tonotopic mean?

A

the organized tuning of different frequencies

18
Q

The function and importance of the outer hair cell

A

Function: makes parts of the tectorial membrane stiffer through an electromotile response
-works to make inner cells more sensitive and sharply tuned

19
Q

Rate saturation

A

= as the sound gets louder, auditory nerve fibers become more broadly tuned
-To circumvent rate saturation, the auditory system uses auditory nerve fibers with different spontaneous rates
-High spontaneous rate fibers respond at low levels of sound
-Low spontaneous rate fibers respond at a broader range of intensities but not at low intensities

20
Q

Cochlear Place Code

A

different portions of the cochlea are tuned to different frequencies

21
Q

Phase locking

A

=many fibers will fire action potentials at one particular point of the sound wave; a neuron fires with the specific phase of the stimulus/response

22
Q

Volley principle

A

= multiple neurons encode frequency as a group

23
Q
A