Auditory Practical Flashcards
Where is the defect in for conductive hearing loss
Defect in transmission of sound from outside world to cochlea
Where is the defect in for sensori-neural hearing loss
Defect in transmission of information from cochlea to auditory cortex
What is the Weber’s Test used to classify
How is the test conducted?
Used to classify unilateral hearing loss
Stem of vibrating tuning fork is held at midline of skull. Where is the sound perceived? The sound is either lateralised to one of the ears or not lateralised (sound prescribed at centre of head)
- affected ear in conductive loss
- in non-affected ear in sensory-neural loss
How is Rinne’s test carried out
Tone of tuning fork is alternately presented by Air conduction and by bone conduction (ie with stem of fork pressed firmly against skull behind ear)
Test each ear separately. Opposite ear should be masked where possible
What constitutes as positive Rinne and negative Rinne results
When tuning fork is moved beside entrance to ear canal, subject will
Positive Rinne:
Perceive tone made by tuning fork (subject more sensitive to air-conducted sound than bone-conducted sound)
Negative Rinne:
Not perceive tone
Analyse the results of Rinne’s test.
What can be deduced if you get a positive / negative result for Rinne’s test
If ear shows positive result for Rinne’s test,
Does not have conductive hearing loss
- may be normal
- OR have sensorineural hearing loss
If ear shows negative result for Rinne’s test,
- has conductive hearing loss if Weber’s test lateralises to same ear
What does the audiogram plot?
Plots hearing thresholds (threshold at which a sound becomes audible/ minimum sound intensity) separately for different frequencies in each ear
At what threshold is someone said to have hearing loss
If someone’s threshold is >20dB worse than average
What levels of severity of hearing loss are there and
what are the magnitude of. Threshold associated with each level?
- mild (20-40 dB HL)
- moderate (40-70 dB HL)
- severe ( 70-90 dB HL)
- profound (90-100 dB HL)
What binaural cues are used to locate sounds in horizontal plane
If sound is presented on one side of head,
1. Interaural level difference (sound louder in closer ear)
2. Interaural time difference (sound reaches closer ear first)
Which binaural cue is primarily used for Low frequencies
Interaural time differences
Which binaural cue is primarily used for high frequencies
Interaural level differences
Implications of profound hearing loss on binaural cues
And therefore effect on ability to locate sounds
Profound hearing loss make one ear insensitive to sound
—> making it impossible for brain to calculate either Interaural Time differences or Interaural level differences
Making it harder, if not impossible to locate sounds
