Audiometry Flashcards
When is pure tone audiometry used?
First test carried out to assess the nature and degree of hearing loss in adults and young children
What is the pure tone threshold?
Decibel level at which the sound is perceived 50% of the time
What does air conduction test?
Entire auditory pathway
What does bone conduction test?
Stimulates the cochlea directly
What does the O on the audiogram mean?
Air conduction
What does red on the audiogram mean?
Right ear
What does blue on the audiogram mean?
Left ear
What does the X on the audiogram mean?
Air Conduction
What does the triangle on the audiogram mean?
Bone conduction
Why is masking used in audiometry?
To isolate the test ear and ensure that results obtained are true thresholds
What are the consequences of not maskin?
An inaccurate measure of threshold
Incorrect diagnosis
May lead to inappropriate intervention
Difficult in later interpreting results
What are the different types of hearing loss?
Sensorineural hearing loss
Conductive hearing loss
Mixed hearing loss
What will a sensorineural hearing loss look like on audiogram?
No significant gap between air and bone conduction thresholds
How does a sensorineural hearing loss occur?
Result of damage to the hair cells within the cochlea or the cochlear nerve
What is presbycusis?
Are related sensorineural hearing loss
What can cause SNHL?
Presbycusis Loud sounds Ototoxic drugs: gentamicin, cisplatin, vincristine Rubella Complications at birth Vestibular schwannoma Genetic predisposition
What will a conductive hearing loss look like on audiogram?
Significant gap between air and bone conduction thresholds with bone conduction being at normal limits
What can cause a conductive hearing loss?
Ear infections
Otitis media with effusion
Perforated ear drum
What will a mixed hearing loss look like on an audiogram?
At parts there is a significant gap between air and bone conduction thresholds but bone conduction thresholds are not at all within normal limits
Combination of conductive and sensorineural hearing loss, which means there is damage in both the outer or middle ear and in the inner ear
What can cause a mixed hearing loss?
Genetic Birth defects Diseases Infections Tumours Masses Head injuries Otosclerosis
What will otosclerosis classically show on audiogram?
Carhart’s notch at 2KHz
What is tympanometry?
Used to test the condition of the middle ear by creating variations of pressure in the ear canal
What can tympanometry be useful in making a diagnosis of?
Otitis media by demonstrating the presence of middle ear fluid
TM perforation by showing a large ear canal volume
What is a type A tympanogram?
Normal eustachian tube function
Eardrum is moving normally with a pressure change
What is a type B tympanogram?
Restricted movement of the drum (likely fluid, but can be ossification of the malleus, incus and stapes)
What is a type C tympanogram?
Drum is moving but something is retracting it inwards towards the middle ear space. Eustachian problems, nasal tumours etc that are preventing normal equalisation
What is a type Ad tympanogram?
Pressure is fine but the ossicles are moving too much allowing too much movement of the ear drum
What is a type As tympanogram?
Eardrum has retracted back onto the ossicles, ossified ossicles
