MI 1.3 Quiz

Frequent or prolonged exposure to sounds with intensities above ____ dB can damage hearing receptors and cause permanent hearing loss.

85

Cochlea

A bony, spiral-shaped cavity coiled 2.5 times; filled with fluid and divided into three sections. It converts stimulus from the outside environment into nerve impulses for transmission to the brain.

Sound intensity is measured as ____________ (dB).

decibels

An increase in wave frequency causes a ____________ in wavelength while wave speed remains constant.

decrease

What is a cochlear implant, and how does it work?

A cochlear implant is a small device inserted surgically in two phases, with a wire placed in the cochlea to do the job of hair cells and direct sound waves from the fluid in the cochlea to the auditory nerve, and with an external implant to pick up sounds from around the patient. Used to treat sensorineural hearing loss.

Mixed hearing loss

A combination of both conductive and sensorineural hearing loss. For example: aging (sensorineural) and middle ear infection (conduction).

What is a hearing aid, and how does it work?

A hearing aid delivers amplified sound to damaged cochlea. It is limited in a ability to aid severe or profound hearing loss (70-90 dB range), but this intervention allows patients to pick up lower frequencies than cochlear implants so it may be the intervention of choice if low frequency hearing loss is involved.

tectorial membrane

A membrane located above the basilar membrane in which the auditory receptors are anchored to.

Round window

A membrane that connects the middle ear with the lower half of the cochlea. The simultaneous outward motion of the round window is called the round window reflex. It aids fluid motion within the cochlea and serves to equalize the hydraulic pressure. By allowing fluid in the cochlea to move, it ensures that hair cells of the basilar membrane will be stimulated and that audition will occur. It is sealed by a round window membrane which vibrates with opposite phase to vibrations entering the inner ear through the oval window. It is essentially a pressure vent.

Oval Window

A membrane that connects the middle ear with the upper half of the cochlea. The vibrations from the ossicles are transferred to the cochlea via the action of the stapedial footplate in the oval window. The footplate of the stapes fits within the oval window and moves in an out with a pump action. The ossicles form a chain extending from the tympanic membrane to the oval window.

Interpreting a Rinne Test

A patient with normal hearing will hear the tone of the vibration longer and louder when tuning fork is held next to the ear, as opposed to when it is held against the mastoid bone. A hearing loss is indicated when a patient hears a louder and longer tone when the vibration is held against the mastoid bone, than when it is held next to the ear. Conductive hearing loss is represented when bone conduction is at least 10 decibels better than air conduction.

Tinnitus

A ringing or buzzing sensation in the ears.

Auditory Ossicles Incus

A small bone in which the malleus rests and then connects to the stapes. It forms the mechanical linkages between the tympanic membrane and the inner ear; delivers sound vibrations to inner ear fluids; amplifies airborne sound by approximately 30 dB

Auditory Ossicles Stapes

A small bone which is connected to the incus, and with its oval footplate connects to the oval window of the inner ear. It forms the mechanical linkages between the tympanic membrane and the inner ear; it delivers sound vibrations to inner ear fluids; amplifies airborne sound by approximately 30dB

How does sound travel through the ear?

A sound creates waves that travel through the air. The pinna captures these sounds which will then travel through a narrow passageway called the external auditory canal. The sound waves reach the eardrum which is a membrane roughly half the size of a dime. They make the eardrum vibrate which in turn vibrates three tiny bones called the malleus, incus, and stapes. These bones amplify or increase the sound vibrations and send them to the cochlea through a wave of air passed onto the oval window. The cochlea is shaped like a snail and is the size of a garden pea. It is filled with fluid and the sound vibrations make this fluid ripple which creates waves. Hair like structures called stereocilia sit on the top of hair cells and are grouped together as hair cell bundles inside the cochlea. The hair cells inside the cochlea (which are on the basilar membrane) ride these waves and the hair bundles are moved. The hair bundle on top of the hair cell turns these movements into a electrical signal. As the hair bundles are moved ions rush into the top of the hair cells causing the release of neurotransmitters on the bottom of the hair cells. The chemicals bind to the auditory nerve cells and create an electrical signal which travels across the auditory nerve to the brain.

Tympanic Membrane

A thin, tough, flexible, fibrous membrane, approximately 1/3" in diameter attached to the external auditory canal. Sound waves from the external auditory canal hit this membrane and cause it to vibrate; reproduces frequency and form of sound wave. Transmits vibrations to the auditory ossicles.

Eustachian Tube

A tube 1 3/4 inches long that connects the middle ear with the back of the nasal cavity; normally closed except when swallowing or yawning. It equalizes air pressure inside and outside the tympanic membrane and allows the drainage of normal and diseased middle ear secretions.

Tympanic Cavity

An air filled cavity nearly filled with the ossicles; located in the thick temporal bone of the skull. It equalizes air pressure inside and outside the tympanic membrane and allows the drainage of normal and diseased middle ear secretions.

External Auditory Canal

An air-filled, S-shaped, 1-inch long passageway connected to the tympanic membrane. Sound waves are funneled down the canal and are amplified; natural acidity helps to protect against infections; secretes cerumen to protect canal from drying out. The main function of the external auditory canal is to transmit sound from the pinna to the eardrum.

Cupulla

An area that hair cells are embedded in

Pinna

Convoluted funnel of cartilage that is attached to the side of the head. It helps to collect sound vibrations near the opening of the ear; directs sound waves into the external auditory canal.

Semicircular Canals

Embedded in the temporal bone; three separate loops; contain clear, water liquid. Hair cells within canals perceive sense of balance and position in space; fluid flows in certain directions when you move your head; different movements affect different canals; aids in maintaining balance and has nothing to do with hearing.

scala tympani

Extends from apex of cochlea to round window. Moves the pressure from the perilymph to the round window.

How do loud noises produce hearing loss?

Extremely loud bursts of sound, such as gunshots or explosions, can rupture the eardrum or damage the bones in the middle ear. Listening to loud noise for a long time can overwork hair cells in the ear, which can cause these cells to die.

Pitch is determined by a sound's ___________, or how rapidly the sound waves vibrate each second. Frequency is measured in vibrations per second, or ___________.

Frequency, Hertz (Hz)

Sensorineural hearing loss

Hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves; also called nerve deafness. It reduces the ability to hear faint sounds. Even when speech is loud, it may be unclear or muffled.

Rinne (Rhine) test

Hearing test using a tuning fork; checks for differences in bone conduction and air conduction

Why is bone conduction better than air conduction in an individual with conductive hearing loss?

In conductive hearing loss, bone conduction is greater than air conduction, because bone conduction bypasses problems in the external or middle ear.

The more energy the sound wave has, the higher the amplitude, and the ___________ the sound seems. Sound intensity is commonly referred to as loudness.

Louder

What are the threshold ranges for each type of hearing level?

Normal hearing: 0-20 dB Mild Hearing Loss: 21-40 dB Moderate Hearing Loss: 41-55 dB Moderate to Severe Hearing Loss: 56-70 dB Severe Hearing Loss: 71-90 dB Profound Hearing Loss: >90 dB

Bone Conduction

Occurs as the eardrum vibrates and moves the auditory ossicles

Conductive hearing loss

Occurs when sound is not conducted efficiently through air to the outer ear canal to the eardrum and/or the tiny bones (ossicles) of the middle ear. It involves a reduction in sound level or the ability to hear faint sounds. This type of hearing loss can often be corrected medically or surgically.

Every sound has two main characteristics: ___________ and ____________

Pitch, intensity

One of the most important tests used to assess hearing is called the ________ ________ Test, where an instrument called an audiometer is used to measure a subjects hearing sensitivity. It tests the ability to hear intensity as well as sense or register all the different frequencies.

Pure Tone

vestibular membrane

Separates the scala tympani from the scala vestibuli

How does sound travel through air?

Sound is created when air molecules vibrate in air in a pattern called waves. These waves are moving through a medium such as air which gives it the ability to be heard

Auditory Nerve

Terminates in a center of the brain stem near the point where the pons and medulla are joined. Branches directly off of the cochlea

What structures is the Inner Ear composed of?

The Oval Window, the Round Window, the Cochlea, and the Semicircular Canals

What structures is the outer ear composed of?

The Pinna and the External Auditory Canal

What structures is the middle ear composed of?

The Tympanic Membrane (ear drum), the auditory ossicles, the Middle Ear Cavity, and the Eustachian Tube

What does an audiogram of conductive hearing loss look like?

The X's and O's are located way below the < and > symbols

How does meningitis affect hearing?

The effects of meningitis include the loss of hair cells in the inner ear, which leads to mild-to-medium hearing loss. Further physical damage of inner ear structures can result in a profound hearing loss. Meningitis can also leave a person with Tinnitus: a persistent whooshing or ringing-in-the-ears sound.

Air Conduction

The process by which sound waves enter the ear through the pinna

Threshold on the audiogram

The softest sound a subject can hear when taking a pure tone test

What is the pathway of sound from the time a sound is generated to the time our brain registers the sound?

The sound waves travel from the outer ear and in through the auditory canal, causing the eardrum, or tympanic membrane, to vibrate. This, in turn, causes the three small bones, known as the ossicles, or the hammer, the anvil and the stirrup, in the middle ear to move. The vibrations move via the oval window through the fluid in the cochlea in the inner ear, stimulating thousands of tiny hair cells. This results in the transformation of the vibrations into electrical impulses finally perceived by the brain as sound.

How is a Pure Tone Test conducted

The test will begin by playing a series of beeps or tones at a distinct frequency. Every time the subject hears the beep he or she is asked to either raise a finger or push a button. The tone will continue to get softer and softer until the subject can no longer hear the beep. The softest sound the subject can hear is called the threshold for that frequency. The thresholds are recorded on a graph, called an audiogram, with the frequencies on the x-axis and the hearing thresholds in decibels on the y-axis.

scala vestibuli

The upper bony passage of the cochlea. Contains perilymph. The pressure of the perilymph is transmitted forward through the scala vestibuli.

What structures in the ear are involved in balance?

The vestibule and the semicircular canals. The semicircular canals are involved in dynammic equilibrium or give you information about direction your body moves. The vestibule houses the utricle and saccule which tells you what position your head is in.

What does the vestibular nerve do?

This carries info concerning body positioning and movement to the brain

What does an audiogram of sensorineural hearing loss look like?

Typical to slope down from the left to right. Also designated when bone conduction and air conduction are in abnormal ranges.

When is the Weber Test used?

Used when hearing is reported as better in one ear than other (bone conduction)

Sound is generated by _____________, which bump into neighboring molecules creating waves.

Vibrations

Sound is a form of energy that travels in __________

Waves

Auditory Ossicles Malleus

a small bone; its handle attaches to the tympanic membrane at a place called the umbo. Auditory Ossicles form the mechanical linkages between the tympanic membrane and the inner ear; deliver sound vibrations to inner ear fluids; amplify airborne sound by approximately 30 dB

Generator potentials in the hair cells can initiate a(n) ___________ potential on the _________

action, cochlear nerve

As the stapes vibrates and hits the oval window, it transmits waves in ______ to the form of a fluid or pressure wave inside the cochlea

air

If hearing is normal, the _____ conduction will be heard twice as long as ______ conduction.

air, bone

Sound intensity is determined by a sound's ____________, or the amount of energy in the wave. Can be thought of as the volume of a sound.

amplitude

Each canal of the semicircular canals has an enlarged area called the ________________.

ampulla

The three semicircular canals contain the fluid __________________.

endolymph

The utricle and saccule each contain the fluid and ________________ and a sensory area called the ____________ which is comprised of hair cells

endolymph, macula

Mechanical deformation of the hair cells causes a(n) _____________ to form

generator potential

The __________ the frequency of the sound, the more frequently the waves vibrate, and the higher the sound's pitch is. Think of frequency as frequent.

higher

___________ frequency sounds stimulate thicker parts of the cochlea on the outside or outer spirals and ___________ frequency sounds stimulate thinner parts of the cochlea (interior or inner spirals)

higher, lower

When the head is upright the utricular macula is oriented _______________________ and the saccular macula is oriented _____________

horizontally, vertically

The decibel scale is a _____________ scale. A sound of 20 decibels is one hundred times louder than 0 decibels; a sound of 30 decibels is one thousand times louder than 0 decibels.

logarithmic

On audiogram, the X's and O's indicate a ___________ test, whereas, the < > symbols indicate a __________ test

pure tone, rinne

What structure in the brain processes sound?

the cerebral cortex

Which one is more superior, the utricle or the saccule?

the utricle