Hearing Assesment Flashcards
How do people with Conductive Hearing Loss hear sound?
Muffled, dull sounds (due to the physical blockage). They may have tinnitus.
How do people with Sensorineural Hearing Loss hear sound?
- Poor discrimination of frequency/speech
- Distortion
- Loudness imbalance (“sudden boom”)
- Some frequencies missing
- tinnitus strong correlation
What are the main causes of conductive hearing loss?
- Congenital Disorders: especially in the outer/middle ear but also in the inner
- Outer and middle ear infections
- Cholesteatoma: benign epithelial tumour
- Ossicular chain fixation: ‘arthritis’ when you get otosclerosis
- Trauma
- Tumours
What is a Cholesteatoma?
Cholesterol-containing-Granulation tissue that forms in the middle ear.
A perforation of the eardrum causes the skin to grow into the middle ear, can be really corrosive and destroy the middle ear → brain.
What is otosclerosis?
A cause of conductive hearing loss when abnormal bone growth around the stapes stops sound conduction to the cochlea
- *Treatment**: fracture the bone and use a bone-conducting hearing aid
- *Cause**: hormonal and genetic causes (higher in pregnancy)
What are the causes of sensorineural hearing loss?
- Congenital Disorders: causing total malformation of the ear, or genetic disorders of ion channels
- Inner Ear Infections: can cause labyrinthitis, which can cause fluid spaces of the inner ear to be filled with bone
- Ototoxic Drugs: ‘Commonly used meds that can cause hearing loss’
- Inner Ear Fluid Disturbaces; menieres disease
- Trauma
- Noise Exposure
- Age
Mostly sensorineural hearing loss is due to damage or loss of what?
Sensory-cells and nerve-fibres in the cochlea.
What is a Central Auditory Disorder and what causes it?
Disorders in processing sound in the brain; hyperacusis, tinnitus, amblyaudia (lazy ear) etc
Causes:
- Peripheral injury; lost connection with the CNS
- Developmental (synaptopathy, neuropathy)
- Neurological disorders
What different types of hearing assessments are there?
- Behaviour: sensitivity to sound, what the person hears (age/competentcy limit; can they respond to these tests?)
- Physiological: less limitations
- Functional imaging: increasing interest
Behavioural Tests (audiology) are what sorts of tests?
Audiometry:
- Pure Tone:
-pure tone air conduction or
- Pure tone vibrator on bone conduction (bypasses middle ear competely)
- Shows data in an audiogram, can show a ear-bone gap
- Speech Tests:
- Speech is best to use over pure tone as thats what we actually hear
How do we do a pure tone Audiogram?
Its to asses the pure-tone threshold to sound at specific frequencies.
- The sound level a person can hear at each frequency is recorded from 125-8000Hz
- The higher the sound level needs to be at each frequency the worse the hearing of the patient
- If it falls within the dark green area the person is considered to have ‘normal hearing’
What would the plot points of a high frequency hearing loss look like on an audiogram?
The points would drop into higher sound level thresholds at the higher frequencies
Whats the benefit of doing a vibrating bone-conduction audiogram with an air-conduction audiogram?
because with an air-conduction test the results could be due to the middle or the inner ear (eg the middle ear could be blocking sound to the inner).
Whereas the vibrating bone-conduction goes directly to the inner ear.
These help us differentiate where the hearing issue lies via the AIR-BONE GAP
What is the purpose of speech audiometry, and what is done?
Speech tests assesses comprehension and detection of speech.
- *Give a set of sentences and words to test in normal vs hard situations:**
- Speech detection thresholds and in background noise
- Make sure they are AGE appropriate
How do you do behavioural Audiology in children?
Much more complex and specialised.
Use visual and bodylanguage cues.
Can be done >4months
How to decipher the Tympanogram results?
Normal: should have maximal sound when there is equal pressure on both sides of ear drum at the peak.
Glue Ear: You’ll never be able to get middle ear pressure the same as the outer ear due to the goo in the middle ear. No response or mobility.
High Negative pressure: massive drop on test to match the highly negative pressure
What hearing loss does she have?
The air-bone gap is significant and she has a 50dB hearing loss! The tympanogram is flat indicating no mobility ie thick fluid in the middle ear!
What is the purpose of doing a physiological measurement and what does this measure?
Useful in people where there’s no behavioural measure.
Allows us to test the integrity of the auditory pathways from the ear → cortex!
You can measure the neural activity of the cochlea and auditory brain centres, by using electrodes on the scalp the measure E.A after hearing a tone.
Each potential shows the activity of each area of the auditory system and how it’s functioning!
Auditory Brainstem Response (ABR) or cortical potentials are used to obtain ______
“hearing thresholds”
This is the response we get back from the auditory nerve when we play different frequency sounds.
Between 0-20dB is normal
How do you test for otoacoustic emissions in a Newborn Hearing Test?
As OHCs are motor cells that vibrate to further propogate the sound wave, they will also propogate vibrations back out the ear.
This can be picked up by a very tight sensitive microphone.
Making a click or a noise, wait a few milliseconds for the sound to come back.
If no return of sound then the baby has failed and their could be a middle ear issue.
*high base frequencies first then low apex frequencies
What is Automated Auditory Brainstem Response and how do you test for it?
Electrodes on the scalp and make a sound.
If there is a response at a low intensity (0-20dB) they are thought to have normal hearing!
If they have no response at 100dB (that’s really loud) then they would be deemed to have extreme hearing loss
