Audiology Midterm

Who founded the field of audiology?

Raymond Carhart

When did audiology emerge?

1960s

Where did audiology start?

Northwestern University

Why did audiology start?

Military-based aural rehabilitation following WWII

What education do you need to become an audiologist?

AuD, 2000 clinical hours, 74 semester hours

Do you need both state licensing and certification?

No, only state licensing

What are the 6 specialties?

pediatric, medical, educational, dispensing/rehabilitative, recreational/animal, industrial

What are audiologist employment settings?

government, schools/universities, private practice, hospital, manufacturing, ENT clinic

When was the first audiology class offered?

1947

What is the prevalence of hearing loss in America?

About 32 million Americans (10%)

Why is audiology both an art and science?

Science of hearing and balance, art of counseling

What are the three parts of the peripheral ear?

Outer, middle, inner

What are the parts of the “central” ear?

Auditory nerve, cochlear nucleus, superior olive complex, lateral lemniscus, inferior colliculus, medial geniculate body, auditory cortex

What part of the ear is this (entire outer region)?

Pinna

What part of the pinna is this?

helix

What is the function of the helix?

gathers acoustic energy

What part of the pinna is this?

tragus

What is the function of the tragus?

Contains acoustic energy in the concha

What part of the pinna is this?

anti-tragus

What is the function of the anti-tragus?

contains acoustic energy in the concha

What part of the pinna is this?

Lobe

What is the function of the lobe?

Gathers acoustic energy

What part of the ear is this?

concha

What is the function of the concha?

funnel acoustic energy into the external auditory meatus

Why does the pinna have grooves?

to best gather speech sound frequencies

What is the “sweet spot” of hearing?

125 to 8000hz (speech sounds)

What part of the ear is this?

External auditory meatus

What is the function of the external auditory meatus?

Acts as a resonator, boosts 125-8000hz

What is the external auditory meatus made of?

1/3rd cartilage, 2/3rds bone

What is cerumen?

Ear wax

How is cerumen produced?

By glands in the cartilaginous portions of the external auditory meatus

What are the dangers of Q-tips?

Cerumen is naturally cleaned through outward skin growth. Q-tips push it towards the tympanic membrane and bone which prevents natural cleaning.

What is this called?

Tympanic membrane

How do audiologists visualize the tympanic membrane?

Pull helix up and back and use otoscope

What should a healthy tympanic membrane look like?

White, translucent, malleus pressed flush against it

What is this called?

Ossicle chain

What are the three bones in the ossicle chain?

malleus, incus, stapes

What is the purpose of the outer ear?

acoustic conduction

what is the purpose of the middle ear?

mechanical conduction

what is this called?

Eustachian tube

Why do children have frequent ear infections?

The eustachian is horizontal during childhood, preventing proper fluid drainage

What is the function of the eustachian tube?

Drain fluid from walls of middle ear cavity

What is this called?

Cochlea

What is the function of the inner ear?

Electrical conduction

Why is the inner ear well protected?

Housed in the petrous portion of the temporal bone

What is this called?

Vestibular system

What is the function of the vestibular system?

Balance

What is this called?

8th Cranial Nerve: Auditory and Vestibular nerve

What nerve is the CNVIII close to?

CNVII: Facial nerve

What are the two “windows”?

oval and round

What is this called?

Basilar Membrane

What is the function of the basilar membrane?

Acts as a “frequency tuner” or fourier analyzer. Splits sound into frequency components.

What is the frequency range of human hearing?

20 to 20,000hz

How is the basilar membrane organized?

tonotopically like a “reverse piano” (high to low)

Why is the basilar membrane organized tonotopically?

The basal end is narrow and stiff, the apical end is wide and flexible

What is this?

Organ of Corti

Why are hair cells called hair cells?

The stereocillia protruding from the cell resemble hair

What are the two types of hair cells?

outer and inner

how many rows of outer hair cells are there?

three

how many rows of inner hair cells?

one

Why do outer hair cells expand and contract?

They are lined with prestin (motor protein)

What is the “trampoline effect” of the hair cells?

When they expand and contract in close succession, the mechanical signal is boosted

What is the minimum audibility curve?

A graph representing normal, average hearing.

What are the axis of the MAC?

y-axis is dBSPL (0 to 140dB) and x-axis is frequency (20 to 20000hz)

How does the minimum audibility curve relate to the audiogram?

The audibility curve (threshold) is the 0dB line on the audiogram

What does the audibility curve represent?

Threshold of hearing

Why is the dB scale used?

The dynamic range of hearing is one billion fold. Log scale condenses this range.

dB SPL vs. dB HL

dB SPL is a physical measurement of sound pressure, while dB HL compares hearing to the average "normal" threshold

What are the axis on the audiogram?

Y-axis is dB HL (-10 to 120dB) and x-axis is frequency (125 to 8000hz)

What is the speech banana?

Frequency and intensity of each phoneme

What is the frequency and intensity of fricatives?

high frequency and low intensity

What is an ear infection called?

otitis media

What is the most common form of hearing loss?

presbycusis (age-related and sensorineural)

What are the different types of hearing loss?

Conductive, Sensorineural, Mixed, Erroneous

What are the two types of erroneous hearing loss?

Malingering (faking) and psychogenic (imagined)

What is conductive hearing loss?

Issue with getting sound to inner ear. Problem with outer or middle ear.

What is sensorineural loss?

Issue with processing sound in inner ear. Problem with cochlea or nerve.

How was hearing first tested?

Tuning fork tests

What are the two types of tuning fork tests?

Weber and Rinne

What is the Weber test?

Place tuning fork on forehead, ask if the sound localizes. If the sound localizes to the affected ear, it is a conductive loss (occlusion effect). If it localizes to the unaffected ear, it is a sensorineural loss.

What is the Rinne test?

Place tuning fork on mastoid. when patient can no longer hear it, move to outside of pinna. If air conduction is longer than bone conduction, hearing is normal. If bone conduction is longer than air, there is a conductive hearing loss.

What are the benefits and limitations of tuning fork tests?

It tells site and type of HL but not degree or configuration (only one frequency) of HL.

What is the difference between psychological and physical sound?

Psychological sound is subjective, physical sound is the measurable disturbance of air molecules

What are sound waves?

Compressions and rarefactions of air particles

What are the two types of waves?

transverse (pependicular to wave motion) and longitudinal (parallel to wave motion)

What are the characteristics of a sine wave?

amplitude (height), frequency (cycles per second), cycle (peak to peak), period (duration of one cycle), wavelength (distance from peak to peak)

How does wave velocity differ between mediums?

Velocity through water is 4.3x times faster than through air

What is the difference between a complex and sine wave?

Complex has multiple frequencies, sine has one

What is the difference between periodic vs aperiodic waves?

periodic is symmetrical, aperiodic varies

What is the fundamental frequency?

Lowest rate of vibration (a systems most natural frequency)

What is the dynamic range of human hearing (Dynes)?

0.002 to 2000

What is the dynamic range of human hearing (micropascals)?

20 to 2×10^8

What is the dynamic range of human hearing (dbSPL)?

0 to 140

What is dB SL (sensation level)?

Intensity of sound relative to one’s own hearing

How can sound bypass air conduction?

Bone conduction: oscillator placed on mastoid

What are the 5 degrees of hearing loss (shown of audiogram)?

mild, moderate, moderately-severe, severe, profound

What is the range of normal hearing on an audiogram?

-10 to 20dBHL

What is the range of mild hearing loss on an audiogram?

20 to 40dBHL

What is the range of moderate hearing loss on an audiogram?

40 to 55dBHL

What is the range of moderately-severe hearing loss?

55 to 70dBHL