Audiology Flashcards
Outer Ear
- Acoustic Process
- Pinna (sound localization)
- External auditory meatus
- Terminates at tympanic membrane (eardrum)
- Cerumen (ear wax) protects ears from foreign items
Function: amplifier, resonator
Middle Ear
- Mechanical Process
- Tympanic Membrane
– 3 layers: epidermal, fibrous, and membranous - Ossicular chain - malleus, incus, stapes (miso!)
- Middle ear muscles
1. Stapedius
2. Tensor Tympani
Eustachian tube opens to equalize pressure
Function: conduction, protection
Inner Ear
- Hydromechanical & chemical process
- Cochlea, temporal bone
- Basilar membrane
- Organ of Corti
Outer Hair Cells - 12k
Innre Hair Cells - 3500
Function: converts mechanical sound waves to electrical activity and neural impulses
Audiometry
testing that measures the range and sensitivity of an individual’s hearing
Pure Tone Testing
- Sounds go through middle & outer ear
- Frequencies tested: 250, 500, 1000, 2000, 4000, 8000 Hz
Used via headphones or external
Response modes: hand raise, button
Threshold: use method down 10 dB, up 5 dB
Bone Conduction Testing
- Tonal stimuli: sound through bone vibration direct to cochlea/ inner ear
Frequencies tested: 500, 1000, 2000, 4000 Hz
Presentation: bone oscillator behind the ear instead of headphones
Auditory Brainstem Response (ABR)
- Used with children who cant complete normal hearing screening or if hearing loss suspected in brain
- Electrodes placed on head, record brain activity in response to sound
Pass or fail for newborns
Audiogram
- Graphic display of hearing test
- Identifies type, degree, and configuration of hearing loss
Frequency range : 125 - 8000 Hz
Otoacoustic Emissions
- Used to determine hair cell function
- Earphone/probe inserted into ear, OAE record response to that sound by vibration
Carhart’s Notch
dip in audiogram at 2000 Hz due to stapes fixation
Pure Tone Average
- Average of 500, 1000, and 200 Hz thresholds
Type of Hearing Loss
identifies the site of damage of the auditory system
Degree of Hearing Loss
refers to the severity of hearing loss (normal, slight, mild, moderate, mod-severe, severe, profound)
Configuration of Hearing Loss
refers to the extent & pattern of loss across frequencies (flat, rising, sloping, high freq, precipitous)
Conductive Hearing Loss
- outer and middle ear
- air bone gap greater than 10 dB
- sounds cannot get through outer and middle ear
characteristics:
Muffled hearing, ear pain,
discharge
Sensorineural Hearing Loss
- Inner ear and/or CN VIII
- Air & bone thresholds are equal
- Both display a hearing loss
Characteristics:
Difficulty hearing, tinnitus,
dizziness
Degrees of Hearing Loss
- Normal 10-15 dB
- Slight 16 - 25 dB
- Mild 26 - 40 dB
- Moderate 41 - 55 dB
- Moderate - Severe 56 - 70 dB
- Severe - 71-90 dB
- Profound 91+ dB
Flat Configuration
AC thresholds within 20 dB of each other
Rising Configuration
AC thresholds for low frequencies at least 20 dB poorer than for high frequencies
Sloping Configuration
AC thresholds for high frequencies at least 20 dB poorer than for low frequencies
Low Frequency Config
hearing loss only found in the low frequencies
High Frequency Config
hearing loss only found in the high frequencies
Precipitous
high frequency thresholds worsen by at least 20 dB per octave
Tympanometry
measurement of eardrum immittance as a function of air pressure in the canal
soft rubber tip is inserted into the ear canal, changing the pressure
Static Admittance
admittance of middle ear system (mobility); height of peak
Tympanic Peak Pressure
the point at which air pressure is equal on either side of the tympanic membrane
Tympanic Width
describes the steepness and shape of the slope of the tympanogram, near the peak
Canal Volume
estimates volume of the air medial to the probe
Type A Tympanogram
Normal
Type As
- shallow compliance
- reduced peak height, normal pressure
- indicates: middle ear fluid, osteosclerosis
Type AD
- deep compliance
- greater than normal peak height, normal pressure
- indicates: ossicular disarticulation, TM Scaring
Type B
- flat (no pressure or compliance)
- no peak
- indicates: middle ear effusion, perforated TM, cerumen occlusion
Type C
- negative pressure
- indicates: eustachian tube dysfunction, negative pressure
Cookie Bite Hearing Loss
Rare type of sensorineural hearing loss (SNHL) that affects the ability to hear mid-range frequencies, between 500–2,000 Hz. It’s named for the U-shaped shape of the audiogram results
Tinnitus
Perception of noise or ringing
in the ears without an
external source
Ear Infections
(Otitis Media)
Inflammation or infection of
the middle ear
Otosclerosis
Abnormal bone growth in the
middle ear causing
conductive hearing loss
Pinna (Auricle)
Collects and directs
sound waves into the
ear canal
External Auditory
Canal
Transmits sound
waves from the pinna
to the tympanic
membrane
Tympanic Membrane
(Eardrum)
Vibrates in response
to sound waves,
transmits vibrations to
ossicles
Ossicles (Malleus, Incus, Stapes)
Transmit and amplify
vibrations from the
tympanic membrane
to the oval window
Eustachian Tube
Equalizes pressure between the middle ear and the atmosphere
Oval Window
Transmits vibrations
from the stapes to the
fluid in the cochlea
Round Window
Allows movement of fluid within the cochlea, aids in pressure relief
Cochlea
Converts sound vibrations into neural signals
Basilar Membrane
Supports the organ of Corti, separates scala media from scala tympani
Organ of Corti
Contains hair cells that transduce mechanical sound vibrations into neural signals
