Auditory Systems Flashcards
What happens to hearing with age?
Hearing acuity decreases with age, particularly higher frequencies.
Medium and low frequencies could be affected with the progression of a hearing loss.
How do you conduct a hearing assessment?
- Tunning fork
- Audiometry
- Central processing assessment
- Tympanometry
- Otoacustic Emission
- Electrocochleography
- Evoked potentials
What is the tuning fork used for?
Used to establish the probable presence or absence of a hearing loss with a significant conductive component
They are used to provide early and general information, when audiometry is not available or possible.
Tell you if the hearing loss is symmetric/asymmetric
What are the aims of a hearing assessment?
Is there a hearing loss? If yes…
- Of what degree?
- Of what type?
What is PTA?
Pure Tone Audiometry
What is an audiogram?
The audiogram is where the hearing thresholds are plotted to define if there is a hearing loss or not. A normal hearing threshold is located between 0 – 20dB
What is central processing assessment?
Assessment of hearing abilities other than detection.
Verbal and non verbal tests
What is tympanometry?
Examination used to test the condition of the middle ear and mobility of the eardrum (tympanic membrane) and the conduction bones by creating variations of air pressure in the ear canal.
What are Otoacoustic Emissions?
The normal cochlea produces low-intensity sounds called OAEs
These sounds are produced specifically by the outer hair cells as they expand and contract
If these sounds cannot be heard it is indicative of hearing loss
This test is often part of the newborn hearing screening and hearing loss monitoring (do not need cooperation of patient)
What are auditory evoked potentials?
Potentials generated by auditory stimuli
Record electrical changes to tell you whether structures are functioning
What is electrocochleopgraphy?
0.2-4.0 ms, electrical activity from the cochlea and eighth nerve. Evoked by clicks or tone burst.
latency relates to how far away the activity being detected is
What is auditory brainstem response?
1.5-10.0 ms, electrical activity from the eighth nerve and brainstem nuclei and tracts. Evoked by clicks.
What are the 3 types of hearing loss?
Conductive
Sensorineural
Mixed
What is conductive hearing loss?
Problem is located in outer or middle ear.
What is sensorineural hearing loss?
Problem is located in the inner ear or the auditory nerve.
Info is not transduce and taken to cortex
What is mixed hearing loss?
Conduction and transduction of sound are affected. Problem affects more than one part of the ear.
How can hearing loss be classified?
Mild
Moderate
Severe
Profound
What are the causes of conductive hearing loss?
Outer ear: Wax, foreign body
Middle ear: Otitis, Otoscerosis
What are causes of sensorineural hearing loss?
Inner ear: Prebycusis, Ototoxicity
Nerve: VIII nerve tumor
What are the treatments?
Treat underlying cause e.g. remove wax
Hearing aids
Cochlear implants
Brainstem implants
What are the main features of hearing aids?
Depending on the type, degree and characteristics of the patient there are many options.
Hearing aids amplify the sound, does not replace any structure.
What are the main features of cochlear implants?
The cochlear implant replaces the function of the hair cells by receiving sound, analysing it, transform it into electrical signals and sending an electric impulse directly to the auditory nerve.
It needs a functional auditory nerve to function.
What are the main features of brainstem implants?
When the auditory nerves are the affected structures, the electrical signals can be send to a set of electrodes placed directly into the brainstem.
What is the issue with brainstem implants?
It is very risky, then it is advised for people with bilateral important auditory nerve damage.
Not great results as the brainstem is not as frequency sensitive as the cochlea
What are some causes of anosmia?
Viral upper respiratory tract infection Nasal polyps Chronic sinus inflammation Ageing Turner's/Kallmann