Assessment Of Adult Hearing Flashcards
What is cross hearing
-sound presented by headphones can cross from on ear to the opposite ear. This happens through the skull
What is pure tone audiometry test
Behavioural test used to measure the threshold of hearing to pure tones of different frequencies
Each ear is tested separately
This test is standardised
What is a otoscopy
Looking down ears
What is sound
-the vibration of air molecules
-objective measurement of sound tells us the pressure
-
What is the measument of pressure
Newtons/ m2 = pascal
What is the range of human hearing
20 micro pascals to 200 pascals
Use a logarithmic scale to keep it manageable
Therefore the scale is decibel (db)
What is the dB HL scale
-audiometry uses dB HL ‘hearing level’
-normalises average threshold values across the frequency range
-found by testing normal hearing adults
-0=threshold
What is the threshod in pure tone audiology
The lowest level of sound the subject can hear 2/2 or 3/4 responses on ascending level
What are the 3 times of hearing loss
-SNHL sensory neural hearing loss
-conductive hearing loss
-mixed
What is SNHL
Sensory neural hearing loss
-problem with cochlear, cochlear nerve, brain related to hearing, auditory nerve or tumour
Conductive hearing loss (airbone gap)
-problem with outer or middle ear
-lower levels of sounds will get into the ear
-perhaps hole in membrane or there is a bony growth
-=stopping sounds getting into cochlear
What is air conduction test
-headphone placed over pinna
-presents sound to the membrane and into the cochlear
-tests the full auditory pathway
What is bone conduction test
-goes behind the back of the persons ear on the auditory meatus
-vibrates the skull
-bipases the outer and middle ear
-sound goes straight to the cochlear
Hearing test results
What does the triangle mean
Bone conduction threshold
Hearing test results
What does the circle symbol mean
Air conduction threshold
Hearing test results
What does 0 mean
Normal/ mean average hearing
Hearing test results
What does further down the graph mean
Sound gets louder
Higher threshold
Bad
(Lower down the graph)
Lower threshold
-good as you can hear quieter sounds
-higher up the graph
What is normal hearing
0-20
What does -db mean
Better than average
What does + db mean
Poorer than average
What does the scale on the audiogram go up to
-10 to 120 dB HL
What does the y axis on the audiogram mean
Intensity
Mild hearing loss
20-40
Moderate hearing loss
41-70
Severe hearing loss
71-95
Profound hearing loss
95-100
What shows conductive hearing loss on audiogram
Gap between air conduction and bone conduction
What shows conductive hearing loss on the audiogram
Gap between air conduction and bone conduction
What shows sensory neural hearing loss on an audiogram
When the bone and air conduction match
What shows mixed hearing loss on audiogram
When air-bone-gap is less than 20 dB HL
What do outer hair cells do
Hair cells act as amplifiers
What is cochlear hearing loss
-outer hair cell damage
-elevates thresholds
-uncomfortable loudness levels
-auditory discrimination and resolution impaire due to smearing of the neural signals
-less able to sort out complex signals like speech
-more susceptible to background noise
What do hearing aids do
-can amplify signals to be above threshold
-can limit the amplification so that intense sounds do not exceed ULLs (uncomfortable listening sounds)
-can reduce noise levels if noise is steady state not speech
What do hearing aids not do
Cannot do anything about poor frequency resolution
Aids do not restore normal hearing
Wide dynamic range compression
Hearing aid boosts the weak sounds but not the louder sounds
Behind the ear hearing aids (BTE)
-worn behind the pinna
-coupled to the concha via plastic tube and ear mold
-DSP aids provided by NHS
Cochlear implant
-tries to replace cochlear
-requires surgery
-electrodes are placed into cochlear
-termed bionic ear but does not restore hearing to normal
-provides additional sensory input to improve use of auditory information in communication
Bone anchored hearing aids
-suitable for people with chronic infection causing constantly draining ears and those with no ear canal
-small titanium fixture implanted behind ear then abutment and sound processor is attached
-connected BAHA transmits sound directly via the titanium fixture using bone as sound pathway
-good for people with middle ear problems
What does atresia mean
No ear canal
FM systems
-sound changed into an electrical signal by a microphone, superimposed on an FM (frequency modulated)radio signal in a portable transmitter and picked up by a portable FM received worn by listener
-transmitter worn by eg teacher
-received worn by eg student
