Module 20: Hearing Flashcards
Audition
The sense or act of hearing
Frequency
The number of complete wavelengths that pass a point in a given time (per second)
*the higher the frequency the higher the pitch and vice versa
Pitch
A tone’s experienced highness or lowness; depends on frequency.
Middle Ear
The chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, & stirrup; malleus, incus, & stapes) that concentrate the vibrations of the eardrum on the cochlea’s oval window
Cochlea
A coiled bony, fluid-filled tube in the inner ear; sound waves traveling through the cochlear fluid trigger nerve impulses
Inner ear
The innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs.
Sensorineural Hearing Loss
Hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerves; also called nerve deafness.
Conduction Hearing Loss
Hearing loss caused by damage to the mechanical system - eardrum and middle bones - that conducts sound waves to the cochlea.
Cochlear Implant
A device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea.
Place Theory
In hearing, the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated
*how we register high frequencies mostly
The brain determines a sound’s pitch by recognizing the specific area on the basilar membrane that is generating the neural signal
Frequency Theory
In hearing, the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch.
*how we register low frequency
Volley Principle
Neural cells can alternate firing - by firing in rapid succession, they can achieve a combined frequency above 1000 waves per second
- part of Frequency theory which explains how we sense low pitches
Amplitude
The maximum amount of vibration indicates a sound’s loudness. The stronger the vibration is the greater the amplitude and thus a louder sound.
Describe the steps of hearing/ the journey of vibrating air pressure through the different parts of the ears.
- Pinna funnels soundwave into the middle portion of the ear through the Auditory Canal
- Soundwaves are channeled towards the tympanic membrane (eardrum) causing the membrane to vibrate
- Eardrum vibrate the Incus, Malleus, & Stapes amplifying the soundwaves and sending them to the inner ear via the cochlea
- Cochlea contains fluid which ripples, rippling tiny hair bundles (Stereocilias).
- Stereocilias convert the soundwaves into electrical signals (potassium ions run to the top of brain cells releasing chemicals at the bottom of the hair cells binding to the auditory nerve creating the electrical signal)
- Auditory Nerve sends the electrical signal to the brain
How do we perceive loudness?
The ear perceives loudness based on the amount of activated hair cells
*NOT the strength of the hair cells response
Note
Even when hair cell loses sensitivity to soft sounds it could still respond to loud sounds
Where does low and high pitch sound register on the basilar membrane?
High frequencies create large vibrations near the start of the cochlea’s membrane
Low Frequencies vibrate closer to the end of the membrane
How do our ears locate sounds?
- Lag Time: The difference in time from sound hitting one ear before reaching the other ear
- Reflection: How sound bounces off the objects in a room
- Inaudible High-Frequency Sound we can’t physically hear but our brain regestures
Pinna
Outer Ear
- gathers soundwaves from our environment and funnels them into the ear canal
Incus
Middle tiny bone
- transfers the vibrations from the Malleus to the Stapes
Malleus
First tiny bone
- transfers the vibrations from the eardrum to the Incus
Tympanic Membrane
Eardrum
A thin layer of tissue that vibrates in response to sound waves
- separates the outer and middle ear
- vibrates due to soundwaves causing the tiny bones to vibrate and so on
Stapes
Last tiny bone
- transfers the vibrations from the Incus to the cochlea
Semi-Circular Canals
Fluid-filled tubes (there are three) that control our vestibular sense (maintain balance & posture; information about motion, head position, & spatial orientation)
Cochlea
Coiled, bony, fluid-filled tube in the inner ear. Sound waves traveling through the cochlear fluid trigger nerve impulses.
Soundwaves/vibrations are converted into nerve impulses by ripples in the ear fluid causing tiny hairs (stereocilia) to translate the vibrations into electrical impulses
Cochlear Nerve
Aka Acoustic Nerve
Sends the auditory information/electrical impulses from the cochlea to the brain
Oval Window
Membrane-covered opening of the cochlea. It vibrates when it receives the sound waves and causes the fluid inside the cochlea to move.
(round window?) Equalizes the pressure in the inner ear - allows fluid in the cochlea to move /
Tympanic Cavity
Houses the bones in the middle ear (Incus, Malleus, & Stapes) - air-filled compartment
Eustachian Tube
Equalizes air pressure between middle ear and nasopharynx (part of the throat behind the nose)
- provides protection for the middle ear from nasopharyngeal secretions and loud sounds
- ventilation & drainage of the middle ear
Auditory/Ear Canal
A passageway from the outer ear to the middle ear that allows sound waves to hit the tympanic membrane
The channel located in the outer ear that funnels sound waves from the pinna to the tympanic membrane.
Is Sensorineural hearing loss permanent?
yes
What are some causes of Sensorineural hearing loss?
Aging, noise, diseases (mumps, meningitis, ménierès), drugs (aspirin, cisplatin, quinine, some antibiotics, some types of chemotherapy), inherited, head or ear injury
Is Conductive hearing loss permanent?
No, it can be treated
What are some causes of Conductive hearing loss?
Blockage in ear canal, infections, damage to eardrums, cysts & tumors, foreign objects in the ear canal, diseases, damage, or changes in the inner ear.
How many parts of a Cochlear Implant are there and where are they implanted?
2 parts
- one externally behind the ear
- the other is an electrode thread placed inside the Cochlea
Does a Cochlear Implant restore a person’s hearing?
No! It does not restore hearing!
It provides a helpful REPRESENTATION of sound
How do air pressure waves become sound?
Air molecules, each bumping into the next, create waves of compressed and expanded air. Our ears detect these brief air pressure changes.
(think pond ripples)
What frequency does short wavelength produce? Long?
Short - high frequency (pitch)
Long - low frequency (pitch)
What do great (high) amplitude sound waves produce? Small?
Great amplitudes - loud sounds
Small amplitudes - soft sounds
How does the ear transform sound into neural messages?
Passing through accessory structures to sense receptors, vibrating air triggers nerve impulses that the brain decodes as sounds.
What are the ossicles?
The ossicles, made up of the three smallest bones in the human body, the incus, malleus, and stapes, transfer the sound wave vibrations from the tympanic membrane to the oval window of the cochlea.
How does the sound wave move through the inner ear?
Accessory structures move the sound wave to the sense receptors (stereocilia) in the inner ear where the wave energy undergoes transduction to neural energy that the brain can interpret.
How does transduction occur in the inner ear?
The motion of the sound vibration against the oval window of the cochlea causes ripples in the basilar membrane, bending the hair cells lining its surface.
How does the nerve impulse move out of the ear?
The hair cell (cilia) movements in turn trigger impulses in adjacent nerve cells, whose axons converge to form the auditory nerve.
How does the message carry to the brain?
The auditory nerve carries the neural messages to your thalamus and then to the auditory cortex in your brain’s temporal lobes.
What is the problem with headphones?
Headphones direct all of the sound waves into the auditory canal and bombard the basilar membrane. In the open air, sound waves disperse and are not all directed to one location.
How does a cochlear implant work?
Cochlear implants work by translating sound into electrical signals that are transmitted to the cochlea and via the auditory nerve, relayed to the brain.
How does the brain detect loudness?
The brain interprets loudness for the number of activated hair cells.
